Methods for attaching rafters to Mauerlat: the main methods and schemes for attaching rafter legs. Do-it-yourself roof truss system: Instructions and Video How to measure the depth of the rafter heel washed down

Plants, flowers - 05.07.2023

Is it possible to single out some main detail in the roof? It is unlikely that this will work, since here each element performs its function. For example, a rafter is a part of a roof that has slopes, which can be called a frame. It is on them that the roofing material will be laid, other elements will be attached. It is on how the truss system is assembled and installed that the final shape of the roof will also depend. But if the work on creating the roof is done independently, then how to fix the rafters? In fact, this is a rather complicated stage of work, on which strength, reliability, and even the geometric correctness of the roof will depend.

The rafter system is a roof frame with slopes, assembled from the rafter legs themselves, as well as a Mauerlat and a ridge beam. Mauerlat is a support beam, which is located along the perimeter of the upper part of the walls of the house, and the ridge beam is installed directly in the upper part of the roof at the place where two opposite rafter legs are connected at an angle.

Designing a truss system is an important task, during which you have to correctly calculate the wind and snow loads that will fall on the roof, as well as take into account other parameters. The first indicators will depend on the climatic region in which the facility under construction will be located. Further, based on the data obtained, the thickness of the walls of the house (bearing) is directly calculated, and the quality and type of material for the roof itself is selected, the angle of inclination of its slopes and other points are calculated.

Attention! Shortcomings and errors made during the design can adversely affect the quality of the roof. In some cases, they can lead to rapid collapse or destruction of the roof.

The design of the rafter system may include the rafters themselves, the ties that will be located between them, runs, additional supports - the so-called rafter legs - and other elements. The assembled truss system usually relies on the same Mauerlat or on floor beams. Mauerlat helps to evenly distribute the load around the entire perimeter of the walls. This is the main difference between this method of attachment. If you fasten the truss system to the floor beams, that is, without installing a power plate, then the main load will fall on the attachment points, and not be distributed evenly over all walls.

On a note! The latter case is not an option if the walls are made of brick, which will begin to collapse over time in places experiencing maximum load. But for a wooden frame, this method is quite suitable.

Table. The dependence of the cross section of the rafter legs on their length and pitch.

Pitch, cm / Length, cm	300	350	400	450	500	550	600
60	4x15	4x17.5	5x15	5x15	5x17.5	5x20	5x20
90	5x15	5x17.5	5x20	7.5x17.5	7.5x17.5	7.5x20	7.5x20
110	7.5x12.5	7.5x15	7.5x17.5	7.5x17.5	7.5x20	7.5x20	10x20
140	7.5x15	7.5x17.5	7.5x20	7.5x20	7.5x20	10x20	10x20
175	10x15	7.5x20	7.5x20	10x20	10x20	10x25	10x25
215	10x15	10x17.5	10x20	10x20	10x25	10x25	-

Rafters are the most essential part of the roofing skeleton. The legs of the rafters transmit thrust to the Mauerlat and the load-bearing walls of the house. What determines the quality of the entire rafter system and the roof as a whole? Experts remind that the reliability of any roof structure will depend, first of all, on the quality of fastening the rafters to the Mauerlat. What principles and features of this process every novice builder should know and how to fix the rafters to the Mauerlat with your own hands, you will learn right now.

Fastening rafters to the Mauerlat: a little "materiel"

To begin with, we propose to consider an illustration that shows two types of truss systems:

The place of attachment of the rafter leg with the base is called the support node. There are many such nodes in the system, but we will touch in detail on the lower fasteners of the frame with rafters. Mauerlat and rafter legs are almost always made of wood, less often of metal. It is more profitable and convenient to use wood, as this material is light in weight, easy to install and durable with proper installation and operation.

Types of support nodes according to the level of rigidity

Support nodes - places where the rafters are attached to the roof elements:

In the case of iron joints, the nodes are fixed, rigid (welds or bolts). Wood is a softer and more dynamic material that can swell, dry out and deform. In this regard, experts recommend performing support nodes, adjusted for possible changes in the shape of the wood. Such nodes can have different degrees of mobility:

Zero Mobility Node- rigid fastening with corners on both sides, in which the fastening of the rafters to the Mauerlat remains motionless.
Connection of the first degree of mobility- the beam can rotate in a circle.
Connection of the second degree of mobility- circular rotation with offset, the installation of special sliders or sleds is provided.
Movable connection of the third degree– the possibility of horizontal, vertical and circular movement.

For any node, whether it is movable or not, at least two types of fixation should be used. For example, notched planks are additionally fixed from the inside with a support beam, while dynamic connections are strengthened with bolts and special steel angles.

About the types of fasteners for rafters to the base

Let's talk about modern fasteners. For the strength and durability of the support units, a variety of metal fasteners are used: beam holders, equilateral, fastening, anchor, reinforced corners, plates, supports, profiles, connectors, anchors, etc. All these spare parts are made of high-quality metal. For dynamic nodes (types 1, 2 and 3), sliders, corners and perforated plates are used. For rigid fastening, stationary connectors, anchors and corners are used.

Such fasteners for the truss system are most often used:

For self-assembly, more than others, perforated mounts are suitable, as they have many holes for self-tapping screws and bolts.

Rigid or movable connections: what to choose

So, we noted that the support nodes connecting the Mauerlat with the boards can be of varying degrees of mobility: from "0" to "3". Zero degree - these are rigid fasteners that exclude any changes in the position of the beams.

Rigid connections: when you need them

Mauerlat is installed when it is necessary to transfer the spacer load from the rafters to the load-bearing walls. This is done mainly in houses made of bricks, panels and blocks. In this case, they try to exclude deformation and shrinkage of the roof in order to prevent changes in the load on the supporting walls. This is where the need for a fixed connection of the truss system with the Mauerlat appears.

Fixed knots fixed with gash

Many experts recommend making appropriate cuts at the point where the rafters are attached to the floor beams for greater strength and immobility of the connecting nodes. These cuts should fit snugly with the Mauerlat. Additionally, such nodes are strengthened with bolts, anchors and metal plates:

Or long screws:

And one more important point: the size of the washed down bar should not exceed 1/3 of its section. Otherwise, the rafter system may lose its bearing capacity:

Rigid knots without notching rafters

The fastening method using a hemmed bar is used in layered truss systems. The rafter is cut according to the template and beveled (to give the roof the desired slope) at the point of contact with the Mauerlat. From the inside, such rafters are reinforced with supporting bars and reinforced with corners on both sides to the base frame:

Another option for a non-butt joint is a rigid fastening of the rafters, reinforced with overlay bars on both sides. Two boards at least a meter long border each rafter leg. One end of such supports is cut at an angle that corresponds to the slope of the roof slope (including rafters). The boards are fastened with a cut to the Mauerlat using long bolts and reinforced steel corners. The bars are attached to pre-marked places, first one at a time. Then, close to the overlays on one side, the rafters themselves are mounted, which are immediately reinforced with the same overlay on the other side. There is an option to install two overlay bars at once, and after that, rafters, but this method is used less often, since it requires more accurate calculations.

When do you need to make mobile connections?

So we come to dynamic reference nodes - connections that can change their position. What is it for? We recall the physical properties of materials - many of them shrink or swell. First of all, this applies to buildings made of pure wood - timber, log house, etc. Natural wood necessarily shrinks, due to which your roof can not only be deformed, but also completely destroyed. To avoid such fatal consequences, the masters recommend performing sliding fastenings of the rafter legs with a Mauerlat (or the upper crown of the log house).

A prerequisite for the installation of sliding nodes is the support of the truss frame on a strong ridge beam. Since the supporting lower nodes are dynamic, the maximum rigidity must be achieved at the roof ridge. The upper edges of the rafters are sawn for a tight connection between themselves and the ridge beam, connected and reinforced with crossbars, metal tapes, plates and corners. It is better to connect a truss element already fixed in the ridge with the crown of the log house.

What is a sliding mount?

The movable connection is carried out by establishing sliding fasteners, called "sleds" or "sliders". Such a node provides for a certain freedom of the rafter legs, which helps prevent the deformation of the roofing system after the natural shrinkage of wooden structures:

Here are the types of sliding supports:

Do I wash down on the rafters if the house is made of timber: an alternative expert opinion

I propose to still file down, but not the rafters, but the upper crown. Firstly, in this case, the risk of curvature of the rafters is reduced, secondly, the “cold bridge” decreases, thirdly, the tangential pressure on the Mauerlat (the upper beam of the log house) decreases, and fourthly, roof insulation is simplified in the future. The disadvantage of this method is that when the upper crown of the beam is cut down, the height of the ridge decreases, therefore, if in the future it is planned to raise the height of the ceiling, one more crown should be provided. But! Such schemes are only suitable for wooden houses, since in brick and concrete buildings the mauerlat must be intact in order to maintain load-bearing qualities.

How to fix the rafters to the beams?

In simple houses, mostly frame houses, the Mauerlat can be abolished. In this case, the rafters are attached to the floor beams. The most reliable option for assembling such a system is the preparation of roof trusses. Each truss consists of two rafter legs, a connecting crossbar and a lower puff. For strength, the trusses are reinforced with central beams and struts:

Floor beams are laid in such a direction that the roof trusses cross them perpendicularly in different planes. The puff performs the main load-bearing functions, is attached to the floor beams with anchors, through bolts, studs and is reinforced with plates and metal corners.

It is possible to attach the rafter legs directly to the beam, which will additionally perform the functions of tightening. To create high-quality support nodes in such a system, two methods of fastening are recommended:

The connection of the rafters with the beam with a double tooth - the cuts are made on the beam and the bevel of the rafter leg (two butt notches on each).
Bolt and clamp fastening. Through fastening may be provided, but if the boards have a large cross section, cuts are made and the parts are connected with long bolts.

Fastening the rafter to the Mauerlat: a step-by-step description

For example, we will describe the process of rigidly attaching rafter joints to the Mauerlat on a simple gable roof.

I. Preparation of the Mauerlat and rafters for work

At this stage, it is necessary to cut out the rafter legs of a given length and mark their step on the basis. The optimal step length of the rafter legs is 60-200 cm. You should also accurately determine the angle of inclination of the rafters.

Mauerlat installation master class:

II. Creating a gash

We carry out washed down on each rafter leg for a tight connection with the base. To enhance strength, you can provide an additional notch on the frame or rafter and install a thrust beam under each rafter leg.

III. Installation of rafters on the Mauerlat

It is necessary to impose rafters carefully so as not to damage other elements of the building (windows, walls, etc.). We start the boards with a cut on the beams and rest them on the ridge beam. First, we install the extreme rafter legs, between which you need to stretch the thread to align all the other rafters.

IV. Fastening each rafter to the Mauerlat

Now that all the trusses are in place, you need to firmly fix the support nodes. We use several of the mounts proposed above for this:

Nails+ steel corners on the left and right side of the joints between the board and the base.
Through bolts or studs+ support bar for cutting the rafters.
Anchors or bolts+ corners or steel plates, etc.

Two overhead boards on both sides of the rafter leg, installed on pre-marked places of the Mauerlat, will help to strengthen the fastening. You can also use wire fastening as a reinforcement of the strength of the connections. To do this, you need to prepare a steel wire twist of 2-3 wires. Its length should be enough to wrap around the rafter leg at the junction with the Mauerlat and fix the ends of the twist on a metal crutch. As a crutch, you can take a long steel bolt, which is mounted into the wall 30-40 cm below the Mauerlat, strictly under the support node.

We will also consider one of the old-fashioned ways - fastening with brackets:

And finally, we invite you to watch the video:

What is the secret of the quality of the truss system: the three main rules of the master

High-quality lumber is half the battle on the way to successful construction. Mauerlat and rafters should not have cracks, wormholes and knots.
The accuracy of measurements, cuts and the uniformity of the position of the fasteners is no less important. If all rafter legs are of the same length and section, then it is better to prepare a template for making cuts and notches.
Washed down on the Mauerlat - loss of the supporting functions of the base by 50% or more. The percentage of strength reduction depends on the depth of the notches.

When the rafter system is ready, it is the turn of the installation of the crate, insulation and flooring of the roofing material. But this is another interesting topic, which we will definitely cover in the next article. In the meantime, we wish you good materials, easy work and good helpers!

In previous articles that described the roof structure, we already said that the hanging rafters rest on the Mauerlat with their lower end, and the upper ends of adjacent rafters abut (either directly or through a ridge board) against each other. In the most simplified version, this is shown in Fig. 1:

Picture 1

I think it is obvious to everyone that with such an arrangement, there are bursting loads on the walls. To reduce them, puffs are added to the truss truss. But let's talk about everything in order.

As an example, let's take a house with a semi-attic in the Volgograd region. The sum of snow and wind loads is 155 kg/m 2 . The dimensions of the house box are 8x10 meters. The thickness of the walls is 50 cm. The angle of inclination of the slopes is 40 ° (see Fig. 2):

Figure 2

STEP 1: We install . In this design, in addition to the usual loads, bursting forces will act on it, tending to move it off the wall. For more reliable fastening, you can add more metal mounting plates to the anchor bolts (or studs) (see Fig. 3). The plates can be fixed to the wall, for example, with frame anchors, and to the Mauerlat, you can use nails, self-tapping screws, and capercaillie.

Figure 3

STEP 2: We determine the required section of the rafters. We make the calculation in the "Arch" tab (see Fig. 4):

Figure 4

The cross section of the rafters is taken 50x200 mm in increments of 60 cm.

A question may immediately arise here. Where do we get the distance from the ridge to the puff (crossbar). We have it equal to 2 meters. Earlier on the site, we already said that before proceeding with the construction of the roof, we need to make a drawing of it on paper, be sure to scale (in all proportions). If you know how, you can draw on the computer. Further, according to this drawing, we determine all the dimensions and angles of interest to us.

Puffs are installed between hanging rafters to reduce bursting loads on the walls. The lower the puff, the more useful it is. Those. the less bursting load falls on the walls. But since in our example, the puffs still play the role of the ceiling beams of the attic floor, we determine the height of their location based on the height of the ceilings we need. I took this height of 2.5 meters (see Fig. 5):

Figure 5

STEP 3: We make a template for the lower rafter cut. To do this, we take a piece of board of the section we need about a meter long, apply it to the Mauerlat at our angle of inclination of the slopes of 40 ° (orient yourself along the pediment) and make the markup, as shown in Figure 6:

Figure 6

The vertical and horizontal lines we need (shown in blue) are drawn using a level. Depth washed down 5 cm.

So let's make a template.

STEP 4: We install a ridge board, through which all the rafters will be interconnected. First you need to outline the place of its installation.

We take the template made earlier and apply it to the Mauerlat. We are interested in the size shown in Figure 7 (here it is 18 cm):

Figure 7

Let's call the lower point on the Mauerlat point "A".

We transfer the resulting size to the top of the pediment, make markings in accordance with Figure 8:

Figure 8

Let's designate the lower right corner as point "B". Now we can measure the distance from the attic floor to point B (the length of the temporary posts).

We install strictly vertically temporary racks from a 50x200 board and put a ridge board of the same section on them. Under the racks for their fixation, you can put a board fixed with simple dowel nails to the floor slabs (see Fig. 9). It is not necessary to fasten strongly, then we will remove it. The distance between the racks is not more than 3 meters.

Figure 9

We fasten the ridge board to the gables with metal brackets. The stability of the racks is provided by jibs.

Perhaps you could see somewhere how hanging rafters are installed without a ridge board (see picture on the left). This method is very familiar to me, we used to do this too.

But when we tried the option with a ridge board, we settled on it. Despite the fact that it takes some time to install the racks and the ridge board, the subsequent installation of the rafters is much more convenient and faster. In the end, you win in time. In addition, the design is more stable and more geometrically even.

STEP 5: We manufacture and install rafters.

We do the rafter like this: we take a board of the desired length, apply a template to one end, mark it out and make the bottom washed down. Then we measure the distance between points "A" and "B" with a tape measure (see Fig. 7-8). We transfer this size to our workpiece and make the top washed down. The angle we need for the top notch is on our template (see Fig. 10). We have it equal to 90 ° + 40 ° = 130 °

Figure 10

Thus, we put all the rafters (see Fig. 11)

Figure 11

The connection of the rafters with the Mauerlat here does not look the same as it was, for example, I think you have already understood that this is due to the presence of bursting loads, which were not in that version. However, in future articles you will see that this option is just one of the possible, and not the only correct one. We will use more familiar to us washed down. The main thing is to securely fasten the rafters to the Mauerlat.

At the top, the rafters will protrude beyond the ridge board. You can drive small bars between them, or you can leave it as is. This, in principle, does not play any role (see Fig. 12):

Figure 12

We fasten the rafters to the ridge with nails or self-tapping screws. It is not necessary to install any additional fasteners here. In general, in this design, thanks to the lower gash, the rafters are obtained, as it were, sandwiched between the Mauerlat and the ridge board.

STEP 6: Installing braces.

We make them from boards of the same section as the rafters. There is no need to make any cuts and cuts here. We make puffs superimposed on the rafters. We fasten them with several nails and tighten them with a threaded stud with a diameter of 12-14 mm (see Fig. 13):

Figure 13

Thus, we install all the puffs and remove our temporary racks on which the ridge board was placed:

Figure 14

Now you can guess the purpose of the small windows in the upper part of the pediment. Through them, ventilation of the insulation will be carried out, which will lie on the ceiling of the half-attic floor (between puffs).

STEP 7: We attach the filly of the cornice overhang to the lower ends of the rafters (see Fig. 15). We make them from boards with a section of 50x100 mm. We make the length of the filly such as to obtain a cornice overhang of the width we need (40-50 cm), and so that it overlaps the rafter by at least 50 cm. We fasten the filly with several nails and tighten it with 2 threaded studs. In the middle part, for additional emphasis on the wall, you can fasten a small bar to the filly with nails or self-tapping screws.

Figure 15

Please note that at the junction of the filly of the overhang with the Mauerlat, we do not drink on it, because. this will reduce it and without that not a large cross section. Here we first make a small cut in the Mauerlat itself (see Fig. 16):

Figure 16

To make the cornice even, use a lace. First put the extreme fillies, then pull the lace between them and put all the rest. In Figure 17 the shoelace is shown in blue.

Figure 17

Step 8: The following steps are already known to us from previous articles. We put the fillies on the pediment and fasten the wind boards (see Fig. 18):

Figure 18

STEP 9: Now we can leave the cornices in the form in which they are.

Let's see another version of the eaves overhangs (see Fig. 19):

Figure 19

Such "earrings" are made from inch boards 10-15 cm wide. We fasten them with self-tapping screws.

Thus, now it remains for us to hem the siding belts to the bottom of the cornices; having fixed a protective film on the rafters, make a counter-lattice and a crate; cover the roof with roofing material. We have covered these steps in previous articles. I think it makes no sense to repeat here and when considering other roof structures in the future.

The truss system is the basis of the roof, the reliability and strength of the roof, its ability to withstand precipitation and wind depends on it. The design of the truss system is determined by the shape of the roof and the features of the layout of the house, as well as the materials used. A do-it-yourself truss system is usually made of wood, but other materials, such as a metal profile, can also be used.

Do-it-yourself truss system

The choice of a truss system is a crucial step that requires knowledge of the design of each type of roof. Rafters can be:

Laminated rafters based on a ridge run and Mauerlat. They are used in the construction of a single-pitched, simple gable roof, as well as one of the elements of a hip and sloping mansard roof.
Sliding rafters - a type of layered rafters used for wooden buildings that give a lot of shrinkage. Their difference is the sliding fastening of the rafters to the Mauerlat, which allows you to compensate for the shrinkage of the walls without deformation of the roof.
Hanging rafters - a system of rafters tied with crossbars or puffs, usually used in the construction of a simple gable roof, as well as the upper rafters of a mansard roof. In the hanging rafter system, there is no ridge run, and in the upper part the symmetrical rafter legs rest directly on each other.
Sloping rafters, otherwise called angular or diagonal. They are used to make a three-pitched or four-pitched roof, as well as for roofs with complex geometry.

Elements of the truss system

Any rafters are designed to distribute and transfer the load of the roof to the walls of the house. The main elements on which the rafters rely are:

Mauerlat - a beam fixed on the upper plane of the walls around the perimeter of the whole house;
Beds - support bars laid on internal load-bearing partitions or columns;
Beams of the ceiling of the upper floor;
Racks and supports;
Runs - horizontal support elements laid along the roof axis on racks.

The truss truss consists of the following elements:

Rafter legs - boards or beams that form the contour of the roof and are laid with a certain step;
Puffs or crossbars - horizontal elements that pull paired rafter legs together;
Struts - supports set at an angle and supporting the rafter legs;
Filly - boards fixed at the lower end of the rafters and forming roof overhangs;

Narozhniki - short rafters resting on diagonal rafters in a hip roof.

Roof options with hanging and layered rafters

All these elements in private construction are usually made of wood - timber or coniferous boards, naturally dried. The tree is impregnated with an antiseptic, which allows you to extend its service life. The thickness and section of the elements is determined by calculation.

Laminated rafter technology

Roof strut installation

Hanging rafter technology

Technology for the implementation of hip diagonal rafters

Since the rafters for the hip roof are installed diagonally, the usual methods of attaching them are not suitable. In addition, the load on diagonal rafters is much higher than on layered or hanging ones, so the material for their implementation must have a larger cross section. You can use a beam with a thickness of 100 mm or more, but practice shows that it is more convenient to make these rafters from two folded and fastened boards of standard thickness.
The diagonal rafters are supported by the upper end on the racks, the lower end - on the Mauerlat bars converging at right angles. They are marked in place, and their main feature is that the cuts are not made perpendicular to the plane of the board, but at an angle of 45 degrees. When making rafters from spliced boards, first one side is performed with oblique cuts, then the second, in a mirror image.
The boards are pulled together with screws, nails or studs. The hip rafters are fixed with overlays and self-tapping screws.

Pulling boards (Hip rafters) with self-tapping screws

A video will help you better understand the basic techniques for building a truss system with your own hands.

When doing any truss system with your own hands, it is important to carefully secure all knots and connections and remember that the roof is the main protection of your house from bad weather. Therefore, it is important not only to make a high-quality frame, but also to choose the appropriate roofing material, for example, corrugated board, and lay it correctly.

When building a truss system, to ensure the reliability of the structure, it is important to monitor every detail. Particular attention is paid to the attachment point of the rafter to the Mauerlat. It is in this place that the main part of the load is transferred to the load-bearing walls. At the same time, it is important not only how to fix what to use, but also washed down the accuracy. After all, if the board is not fully supported, then it can break and lead to the collapse of the roof. In the article, we will consider how to cut down the rafters and what methods exist for this.

Varieties of fastening rafters

Depending on the design solution, the presence of internal walls and the calculated load, various types of fastening are used. Each of them implies its own version of the preparation of rafters for docking with the Mauerlat. The three main attachment methods are listed below:

hard;
layered;
sliding.

We will not consider the latter option, since when using it, it will not be necessary to make cuts. It is usually used when constructing a roof on houses made of timber. It is most suitable, as wooden walls shrink over time. Because of this, the truss system can change the geometry and leaks will appear.

In other options, you will have to make accurate cuts. You will need accurate measuring instruments, a construction pencil and an electric or chainsaw.

The strength of the roof depends not only on how the cuts were made correctly. Consider the following tips:

For rafters, select high-quality materials, since even if you make accurate cuts, the bar may not withstand the load. You can’t save here, because this part takes all the load on itself.
Mounting points with Mauerlat must be free of wood defects, such as knots. Although they are stronger than wood, turbulences form around them, which break at the slightest load.
When installing a roof, do not hesitate to ask for help, as this is a dangerous and responsible business.

A well-made junction of the rafter leg and the Mauerlat guarantees a long service life of the structure.

Cutting out a seat

It is important to understand that it is impossible to perform a perfect gash on a construction site. The reasons may be different: lack of high-precision tools, uneven position of the Mauerlat, uncomfortable position, and so on. Therefore, relative to the design value, the slope angle of the ramp may change. Here, the main thing is to maintain a single line of position of the rafters.

The easiest way to make the same washed down on the rafters is to use a template. True, this option is not suitable in all cases, so often the roofs are uneven. Then you have to calculate the angle and place of cutting on each rafter individually.

For the basis of the template, take a piece of board, a piece of fiberboard or plywood, even thick cardboard will do. On the workpiece, draw a line from the bottom edge at a distance of no more than a third of the width of the rafter. The same line must be drawn on all the bars that you plan to cut. The fact is that it is not recommended to cut deeper because of the loss of strength. Next, mark the points at which the rafter will be adjacent to the Mauerlat, make a perpendicular line relative to the previous line.

Now let's move on to making a template by determining the angles of the vertical and horizontal parts of the notch. To do this, attach the workpiece to the end of the Mauerlat, keeping the slope of the future roof. Opposite the corner should be the intersection point of the lines that were made before. Draw the lines of the triangle and cut out the resulting template.

Before transferring the markup to the rafters, check the accuracy of the finished product. Walk along the roof and check the degree of abutment along the entire length of the Mauerlat. Make adjustments if necessary, but don't expect perfection. Drops of 2-3 mm are acceptable.

The maximum concentration is important so as not to go beyond the outlined boundaries. If you are not confident in your own abilities, then use a hand tool. So you reduce the percentage of marriage and the time for rework.

The second cut is made with an ax, as the power saw can be stuck. It also requires skill and strength. It is important to make sure that the ax is quite sharp, then the case will be argued better and chips can be avoided.

Finally, check the resulting file with the template and make adjustments if necessary. After that, you can install the finished rafter leg or make seats on the remaining parts.

Cutting for a direct joint with Mauerlat

An easier option is to make a butt joint. To do this, you need to determine the location of the cut and the angle of its inclination. For this purpose, two options can be applied: theoretical and practical.

For the theoretical method, you need to be well versed in geometry and calculate the desired angle on paper. Divide the distance from the ridge to the eaves by the length of the rafter. So, you will get the cosine of the desired angle. In order to transfer it to the workpiece, you can use either a miter saw or a special square.

If you don't have a special tool on hand, make a simple template. Take a durable material, such as chipboard. On the sheet, mark 500 mm along the bottom edge, then determine the tangent of the required angle and multiply by the measured length. So, you get the second side of a right triangle. After marking all the borders and cutting out the workpiece, get the desired angle. The sawn parts can be mounted immediately or wait until the whole set is made.

In practice, you can easily mark up a separate rafter by attaching it to the design position. To do this, set the beam so that its lower part is flush with the Mauerlat. Draw a horizontal line from the corner to the bottom of the rafter, it should be strictly parallel to the wall. Now you can safely saw off with any tool at hand and install the part. The rest will serve as a template for the remaining rafters only if the base is even.

Knowledge of geometry helps not only in determining the angle of the washed down rafter leg, but also in determining the height of the roof, the length of individual elements, and so on.

The truss frame sets the geometric and operational parameters of the pitched roof. Due to violations in the installation technology, due to flaws in the manufacture of its elements, distortions of the system, traditional leaks, holes in the coating appear, threatening emergency situations. In order to build a reliable and stable roof structure, you need to clearly know how the sawing and installation of rafters is performed, followed by fixation to the supporting elements.

Classification of rafter legs

Rafters, or rafter legs, are wooden or metal beams installed on the house box at a given angle. They determine the configuration of the roof structure, take on and steadfastly resist the sum of permanent and temporary loads acting on the upper enclosing system of the building.

The structural simplicity of the rafter legs is extremely deceptive. In fact, these are quite complex elements that require careful marking and accurate cutting. Inconsistencies in the connections of the rafter legs with the Mauerlat, with each other and other components of the system lead to a change in the shape of the slopes, a violation of the integrity of the coating and the destruction of nodes.

On the other hand, the competent installation of rafter legs can correct some errors in the construction of the house box, and not aggravate the situation by clearly repeating and increasing the wall height differences. True, in such situations, the frame elements are made individually and scrupulously adjusted in fact directly at the facility.

However, before dealing with the specifics of installation, you need to find out what their design differences are, according to which the rafter legs are divided into two groups, these are:

Hanging. Type of rafters that do not have an upper support. At the top of the roof, the rafter legs rest against each other with their ends. So that under the weight of the components of the roofing cake and snow, such a design does not burst the Mauerlat beam, the hanging rafters are connected with a horizontally installed puff.
Layered. A kind of rafter legs, stacked on two supports of different heights. At the top, they most often rely on a ridge run installed in the cross to the rafters, less often they rest against each other, cut down at an angle. The bottom rests on the Mauerlat beam or rests against it.

The scope of their application and installation technology depend on which group the rafter legs belong to. The hanging variety is collected on the ground, and the trusses, made in the form of peculiar triangles, are raised to the roof and mounted in a form completely prepared for installation.

The advantage of building a truss frame using hanging technology lies in the safety of work and the ability to perform nodal connections as accurately as possible. If the simplest version of a hanging truss with a puff at the bottom is used in the construction of the roof, you can abandon the Mauerlat device, in place of which a narrow leveling board is quite suitable.

The disadvantages of hanging technology are accompanied by advantages. For example, a truss assembled on the ground is much more difficult to transport to the installation site than boards and timber for layered rafters. There are restrictions on the spans to be covered: the limit is 14 m, above which it is unreasonable to install wooden beams prone to sagging without intermediate supports.

The rafter legs of the layered group both top and bottom are based on independent structures. The top of them is laid on a purlin structure, which is mounted on the floor beams or on the bed, replacing the Mauerlat on the inner wall. The bottom is either installed on the Mauerlat, or rests against it, catching on the bar with a tooth or a support bar sewn instead of a tooth.

The advantage of layered systems is rightfully recognized as the possibility of overlapping almost any span in size. It’s just that with an increase in the overlapped space, the design becomes more complicated: it is supplemented with struts for a couple with racks, additional runs, coupled with beds, fights.

The layered structure is assembled and mounted longer, because. it is built not from farms, but from individual elements. However, just this scheme has more opportunities to correct the shortcomings of a box or an unevenly settled log house. Because layered rafters are stacked individually, it is possible to slightly change the position and size of the node, in order to eventually form a perfectly aligned slope plane.

The specifics of the manufacture and installation of rafters

It is clear that for the construction of the truss system, lumber will be needed - long-length products of timber processing enterprises with clear geometric parameters. You will need a board or timber, on which, of course, there are no mounting cuts and cuts for installation.

Why are cuts and cuts needed? The fact is that when placed on an edge, boards and beams have too little support area. They are in contact with the Mauerlat with only one vestma in a thin line, because of which, at the slightest load from above, they can tritely “move out” from their position and drag the entire structure with them.

In order to increase the area of \u200b\u200bsupport in the junction of the rafter and the Mauerlat, or it and the additional run, a corner cut is selected in the beam or board, a tooth is cut out or a support bar is sewn on. If the top of the rafter is paired with a mirror-opposite counterpart, then for a reliable stop, you will need a gash, the plane of which must be clearly perpendicular to the horizon.

The basic rule in the construction of truss frames is that the support sites selected in the lumber are strictly horizontal and vertical. At the slightest violation of horizontality with verticality, stability is lost, structural parts are displaced under their own weight and load, up to the complete destruction of the system.

Note that the nodes of the truss systems are entrusted with the obligation to ensure the possibility of a slight displacement and rotation when the load is exceeded. These movements are necessary in order for the structure to bend slightly, move slightly, but not collapse and remain stable.

These subtleties should be known both to the master who decided to do the manufacture and installation of rafters with his own hands, and to the owner of the house under construction, who does not want to pay for the poor-quality labor efforts of the builders' team. Let's analyze the common options to understand the essence of the process.

Hanging roof frame construction

Consider an example of the construction of a truss system over a log cabin of a bath. The span between the walls is small, it is easier and more reasonable to block it with a hanging structure, the installation of which will be carried out on the bypasses of the ceiling beams - matrices.

The log base is an almost ideal option for installing hanging systems, because. it is easiest to cut it into the horizon, eliminating the need to adjust the rafters in case of a violation of the geometry of the foot. There is no need for a Mauerlat device. However, the puff will have to be moved up in order to bypass the upper crown of the log house and form a useful attic space.

Before performing the installation of the rafters, a phased preparation of the log house is carried out. On both sides of the foot, we align the bypasses according to the lace tied to the nails hammered into the two extreme beams. On top of the bypasses, we cut off the slab so that the edge of each beam ends with a flat horizontal platform.

The surface formed after squeezing the upper bulge of the log along the edges of the beams is aligned to the horizon according to the level. We apply the specified control tool to three or more beams at the same time. If the level is not long enough to carry out such a check, use a long rail or board instead.

After squeezing all the excess, we mark the nests for the rafter tooth. To do this, we again use nails and lace. Note that it is possible to draw nest sampling sites on the bypasses both before the construction of hanging trusses and after. However, it is much more convenient to make nests before making rafters. They will help to carry out the fitting with higher accuracy.

To facilitate your work, it is advisable to find the center of the log house from the side of future tongs. At these points, it is recommended to nail along the control rail, one of the edges of which will indicate the axis of symmetry. You can do without rails if you already have some experience in the construction of roofs.

We sew two inch boards 10–15 cm longer than the designed length of the rafters at the top with a nail or bolt so that they can rotate around this connecting point.
On the rail installed in the center of the future tongs, we mark the design height of the truss system. We put one more mark above it - this is the height of the tooth, more precisely, the length of the vertical laid off from the base of the tooth to its top.
We set the boards sewn at one point to the extreme bypasses so that the corner of each board rests against the future socket under the tooth.
We combine the connection point of the boards with the upper mark on the rail, which determines the length of the rafters with the tooth.
From the lower corner of both rafters, we set aside the height of the tooth, return with the template blank to the ground and cut out the tooth according to the markup.
We return the template blank to its place, install it by inserting the teeth into the sockets intended for them. It may happen that after installation, the top of the workpiece does not match the directions of the rail. Then you need to pull out the nail and adjust the position of the top, be sure to mark a new point.
After fitting the top, we draw a vertical line of their upcoming joint on both boards, measure the size of the crossbar and mark on the trimmings of the board the shape of the overlays for the upper joint of the rafters.

If everything turned out exactly and no more adjustments are required, the template is ready. We return with him to the ground. We disassemble the workpiece and make cuts along the marked lines. The parts obtained as a result of fitting and fitting will serve as a standard for the practically in-line production of roof trusses in the required quantity.

We will assemble hanging farms on the ground. Their installation, as well as fitting, should be carried out by at least two people. One master simply can not cope with such work. The performer at the top will install the truss, and the second one will change its position according to the plumb line. The position of each leveled and installed truss should be fixed with temporary struts.

To increase the stability of the system, we will install racks under the rafters:

Let's mark the matrices under the place of installation of additional supports in an already proven way: we will hammer in a nail from opposite sides and pull the cord.
We will hollow out nests in the logs according to the markings.
Let's try a piece of a bar to the installation site. We mark on it the line washed down, taking into account the height of the spike.
We will make a rack and two linings for attaching it to the rafter.
Install the support made and fix the position of the truss truss on the other side in the same way. According to the verified scheme, we continue to work until we equip each rafter with an additional support.

To ensure the rigidity of the hanging system, the truss trusses are connected by wind ties - boards, poles or slats nailed from the inside of the structure. On the outside of the truss frame, rigidity will increase due to the construction of the crate.

The rafter legs are attached to the matrices with 200 mm nails or angle brackets. In this regard, metal corners and plates with perforation for fasteners significantly lose to traditional methods. To the sidewalls of the rafters we nail fillies made of a board, the width of which is half the material used in the manufacture of the rafters.

The length of the filly should be 70 - 80 cm more than the designed width of the overhang. This distance is necessary for their reliable connection with the rafter legs. The fillies can be cut in advance, or without preliminary cuts, you can nail the trimmings of a narrow board to the rafters, and then draw up the line of the eaves. However, the first option is more convenient and economical.

In most cases, as in the example above, fillies must be partially buried in the mats bypass, for this:

We note in fact the width of the filly at the bypass.
We make two cuts with a saw according to the markup for 2/3 of the thickness of the filly. We also saw the log between the extreme cuts with a saw. We refine the recess with a chisel, accompanied by a hammer.
We install the fillies in the formed recesses, sew them with rafters with nails 100 mm long.

Upon completion of the installation of all fillies in the last ones, we hammer in a nail. We pull the control cord and mark where to saw off the excess.

The device of the layered roof frame

In the construction of a truss frame using layered technology, there is much in common with the installation of a hanging structure. The fitting is carried out in almost the same sequence, so it makes no sense to describe the actions twice. The main difference is in the methods of forming the upper node, because the tops of the layered rafters have a support - a ridge run.

If at the top the layered rafters are tritely based on a ridge run, they are laid either with a run, i.e. parallel to each other, or with a strictly vertical joint, similar to the docking of hanging legs. However, in most cases, they try to fix the upper part with a notch or a vertical cut with a tight fit to the ridge beam.

There are schemes according to which the layered rafters are based not on the ridge, but on the side run. In such situations, the top is formed according to the hanging principle, and the point of support on the girder is made out with a corner cut.

Let us analyze the most popular option in private construction for the construction of rafter legs with support on the lower corner cut and on the ridge run through a vertical gash. Note that the maximum depth of the cut should not exceed 1/3 of the width of the board.

Option for marking with a construction square:

On the square, we mark the height of the roof and half the span on a scale. These values reflect the slope of the slopes and set the main angles. The proportions must be exactly maintained.
If further use of the square is not planned, then the delayed points can be marked with screwed bosses or short screws with screws, if planned, it is better with paint that is removed with a solvent.
We apply a square to the board laid flat with the side on which the height of the roof is marked. We draw a line according to the indications of the square - this is the line of the upper cut of the rafter - the section of its interface with the ridge run.
Cut along the marked line with a circular saw. Lay the board for sawing flat, as it should be when cutting in width. Longitudinal cuts are made with setting on the edge.
From the top of the formed angle, we set aside the length of the so-called diagonal. This is the distance from the junction point with the run to the outer edge of the Mauerlat or the upper trim, if a frame house is being equipped.
We move the square to this point. We draw a line parallel to the first.
We turn the square over, move it along the workpiece so that 2/3 of the total distance is on the left, and 1/3 on the right. In the picture, these are 8ʺ and 4ʺ.
The line of a smaller segment will just designate a cut for us.

At the end, we draw the outline of the cornice overhang on the board, cut it along the outlined lines and use the rafter blank made by ourselves to saw the rest of the roof elements.

You can apply the described method without a building square and marking the parameters of the roof on it. It is enough to imagine the process in order to set aside the necessary distances with a conventional drawing tool. However, without experience, you can get confused in the calculations of angles and segments.

To help novice builders, a template has been developed with options for forming corner cuts. It will help you navigate the manufacture of rafter legs from the most common lumber in this area.

In cases of laying rafter legs with notches in the upper and lower parts, it should be remembered that the depth of both notches must be the same so that the roof slope does not change during construction work. Usually, for the device of two equal cuts, an auxiliary bar is used, the thickness of which is not more than 1/3 of the thickness of the board.

The rafter blank is then installed with an edge on the Mauerlat and on the run. The bar is applied on the side in the area of the lower and upper nodes to outline the cut.

If the cut is needed only in the lower part of the rafter, and the top will be based on the run with a cut, the board is installed at the bottom on the Mauerlat, and at the top on the run and the bar, so that as a result of cutting, the slope of the slope does not change. At the bottom, a second bar of the same size is applied to the future node and the outline of the future cutting is outlined with it.

The same methods are used to form cuts with a tooth. The difference is only in the form washed down.

The installation of layered rafters begins with the installation of two extreme trusses. The elements are mounted one at a time, their position is carefully checked using a plumb line. Most often, extreme farms are arranged from paired boards, because. they carry more load. They are fixed with temporary spacers, then connected with a cord or rail to indicate the plane of the slope.

Ordinary rafters located between the extreme load-bearing trusses are installed according to the instructions of the laces. If necessary, correct the position of the legs according to the actual situation.

Video about installing rafter legs

Installation of rafters with fastening with metal corners:

How to make rafter legs with cuts for landing on a Mauerlat:

The device of the truss frame under the roof of the garage:

We have given and described only a part of the methods for constructing truss frames. In reality, there are much more manufacturing and installation methods. However, an analysis of the basic options allows you to perfectly understand how to properly make rafters and truss trusses for the roof, how to saw them down before installation.

KakPostroit.by 21.02.2017

The truss system of a gable roof is a simple design that is available for a do-it-yourself device even for a novice developer. It is only necessary to make preliminary calculations, familiarize yourself with the details and stages of the construction of the roof, and calculate the materials needed for installation. When calculating, it should be taken into account that the bearing capacity of a gable roof depends on the influence of loads from wind, snow, and the weight of materials on it.

In order to make the process of building a gable roof truss system as easy as possible for you, below is a detailed step-by-step instruction for installing a truss system with your own hands.

Requirements for building materials

For the installation of a truss system, the best option would be to use sawn timber from coniferous wood - pine, spruce or larch, grades I - III.

The material for the rafters is taken not lower than grade II, the Mauerlat is made from boards or timber of grade II, for racks and girders material of grade II is taken, the lathing is made from grade II-III lumber, it depends on the roof. Crossbars, puffs are made of Grade I material. On linings, linings, material of grade III can be used.

Note! Lumber must be dry with a moisture content of not more than 20%. Before installation, it should be treated with flame retardants and antiseptics against fungal diseases.

You need to store lumber under a canopy, providing protection from the sun and moisture. Level the storage area, shift the lumber with linings for ventilation.

For installation, fasteners are required: ties, plates, studs, bolts with washers and nuts, self-tapping screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when fastening the Mauerlat, they are fastened with nails or self-tapping screws.

KR corners serve to attach the rafters to the Mauerlat, prevent the rafters from moving.

All fixing material must be made of high quality material and protected against corrosion.

Tools for the construction of the truss system

To install the gable roof truss system, you will need the following set of tools:

tape measure, different lengths 5, 10, 20 meters;
markers, pencils;
cord, for stretching;
hammers, various purposes, nail puller;
scissors, for cutting;
roofing knife;
putty knife;
scotch;
hacksaws, electric saw, electric drill with various drills and nozzles;
screwdriver with nozzles;
markings, horizontal and vertical levels;
rails, rulers;
mounting foam;
safety belt and rope - for safe work.

Keep all roofing tools in a tool bag for safety.

Types of truss systems for a gable roof

sent rafters

They rely on the Mauerlat and racks installed on the inner wall, with a step equal to the rafters. To give rigidity during spans of 6 m, struts are additionally placed.

The scheme of the rafters of a gable roof

hanging rafters

If the building is of a small width, it is possible to arrange a truss system when the rafters rest on the mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Such roofs can sometimes be arranged without a Mauerlat. The rafters are installed on the wall, using gaskets, on the rafters in this embodiment, a bending moment acts.

To unload, put wooden or metal lining. They securely reinforce the corner. For hanging rafters of a larger span, a headstock and struts are installed. For hanging systems, the rafters are arranged with a larger section, and the lumber is chosen not lower than grade I II.

Scheme of hanging rafters of a gable roof

Calculation of the truss system

It is possible to determine the cross-section of a gable roof beam in the truss system by collecting all the loads acting on it: the weight of the coating, lathing, snow, wind pressure, precipitation.

Permanent loads can be determined by the weight of 1 m2 of roofing, battens. It is important that the weight per 1 m2 of the roof is in the range of 40-45 kg.

Variable loads from snow, wind are calculated according to the tabular values of SNiP normative documents, depending on the height of the building, temperature zone. The load from snow is equal to its weight multiplied by a coefficient depending on the slope of the slope. All these calculations are carried out during the project.

And if there is no project, and the roof is being erected on a small building? You need to look at the construction of a house in the neighborhood, which is being carried out according to the project, the roof area is the same as your building. The gable roof truss system will serve as a model.

Rafter beam dimensions

At the top point, a ridge is laid that connects the rafters. The height of the ridge depends on the slope of the roof. The slope is influenced by the choice of coating material. The minimum dimensions are:

for tiled roofs, slate 22 gr.;
for metal tiles - 14 gr.;
ondulin - 6 gr.;
corrugated board - 12 gr.

The optimal angle is 35-45 gr. slope, provides a quick discharge of water and snow. In regions with strong winds, the roofs are made flat and then the angle of inclination is within 20-45 degrees.

You can determine the height by the formula: H \u003d 1 / 2Lpr * tgA. Where A is the angle of inclination, L is the width of the building.

The task is simplified when using a ready-made table. The coefficient depends on the width of the building and the angle of inclination. Multiply the coefficient by 1⁄2 of the width of the building.

The rafters are made from pine or spruce bars, with a section of 50 × 100 mm, 50 * 150 mm.

The size of the rafters depends on the pitch. The pitch of the rafters is smaller, a larger number is installed, the cross section will decrease. The distance between the rafters at a gable roof is in the range from 600 mm to 1800 mm, it all depends on the design of the roof and the materials used for its construction.

The roof does not end at the level of the walls, it is extended 500 mm outwards. The rafter leg can protrude, or a board or bar is built up. In this case, moisture does not fall on the wall, the foundation is not poured.

Step-by-step installation of the design of the gable roof truss system

The gable roof truss system consists of the following elements:

Mauerlat.
Lie down.
Racks.
Rafter.
Struts.
Puffs.
Crate.

Mauerlat installation

Mauerlat fasteners to a monolithic reinforced concrete belt

Mauerlat evenly distributes the load on the walls of the building, its installation can be done in several ways:

fasten to the wall through a reinforced concrete belt with studs;
studs are inserted into the masonry;
a simple and common way for simple roofs, fastening with wire rod.

For him, take a bar with a section of 100 × 100 mm, 150 × 150 mm or 200 × 200 mm. Which section to choose depends on the size of the roof and its coverage. The Mauerlat is joined along the length, for this, make a 100 mm cut, 500 mm long, fold the bars and fasten with studs.

In the corners, the Mauerlat is tied with cuts to the floor of the beam, fastened with brackets or bolts. For wooden buildings, Mauerlat is the last crown. On brick walls, make a monolithic reinforced reinforced concrete belt, with a section of 400 × 300 mm. Align the pins with a thread of 12 mm in diameter along the belt, through 120 mm, for fastening.

Drill holes with a diameter of 12 mm in the Mauerlat, lay them so that the pins go into the holes. Tighten with nuts from above. Previously, we lay two layers of roofing material or roofing felt under the bar. On the outside of the wall, lay the Mauerlat with bricks. Laying the Mauerlat on a horizontally and vertically even base. It is necessary to check the horizontal level of the surface. Check diagonals. Align with pads if necessary.

Installation instructions for beds, racks, rafters, struts and puffs

Do-it-yourself do-it-yourself installation of a gable roof truss system is carried out in the following order:

To carry out the installation of the bed, with the sent rafters.
Mark the installation step of the rafter legs.
Prepare according to the size of the rack.
Install them, if necessary, unfasten them with spacers.
Lay a run. Check geometry. Install fastener.
Try on the first rafter leg, mark the cutting points.
Mark the points and install the rafters at the beginning and end of the roof, pull a cord between them in order to align the rest of the elements with it.
Having installed the rafter leg, we attach it first to the Mauerlat, then to the ridge run, to each other.
Screw every second leg with wire to the Mauerlat.

The fastening of the rafters to the Mauerlat is done with the help of notches, thrust corners and a hemmed support bar. Reinforce with nails or staples.

Methods for attaching rafters to the Mauerlat

Install the support posts on the beds or linings and linings. A bed is a beam 50 × 100 mm or 50 × 150 mm, laid on the middle wall along a roofing felt lining. Place brick columns under the lining, 2 bricks high.

The rafter legs are connected to each other on the ridge. Consider the common connection nodes of the truss system:

They make cuts at one leg and washed down at the other. Insert one leg into the cut of the other and fasten with a bolt.
Install overlays, wooden or metal.
With the help of cuts in the run, they are fixed with nails or bolts.

Methods for connecting rafters on a ridge

For the stability of the roof to wind loads, puffs, struts and runs are installed. The tightening is a bar 100 × 150 mm, runs and struts are made from a bar 50 × 150 mm or 100 × 150 mm.

With the installation of contractions, the reliability of the rafter design increases. The sections of the beam are the same as the rafters. They are attached to the legs with bolts or nails. The bracing device adds rigidity to the structure. They are installed tightly, to the surface of the rafters.

Lumber has a standard length of 6 m. Rafters can be longer. Then you need to connect them. There are several connection methods:

Fasten by applying bars on both sides at the junction, connect them with nails in a checkerboard pattern.
Overlap, one part of the rafter to another, at a distance of 1 meter, fasten with nails in a variable order.
Run a cut obliquely, cut out part of the legs of the rafters, connect them, reinforcing them with bolts.

Lathing device

A crate is laid along the roof rafters. It serves to distribute the load from the roofing material, snow on the rafters. It plays the role of an air gap between the roof and the truss system.

The design of the crate depends on the accepted roofing material:

under the soft tiles, the crate should be made continuous, an anti-condensate film is laid on the rafters, it is pressed against the top with a counter rail, the crate is nailed onto it, then the OSB boards and the lining carpet, the tiles are laid on top.
under the roof of the corrugated board, the crate should be sparse. The step of the lathing depends on the brand of corrugated board, its thickness and the angle of the roof.
make a crate for standard slate in increments of 500 mm from a bar 75 × 75 mm or 50 × 50, as well as boards from 30 × 100 mm. It is necessary to take into account the design features of the roof, with the final choice of a suitable option.

The lumber from which the crate is made is pine of the first or second grade. It is advisable to take a width of no more than 14 cm. With a width of more, the boards can warp and damage the roofing. The length of the nails should be three times the thickness of the crate. Lay boards along the ridge. Set the first board of greater thickness to the height of the roofing.

To arrange a continuous crate along the slope of the roof.

With the first layer, lay a board along the ridge from it at a distance of 500-1000 mm next, and so on. With the second layer, lay the crate in the direction along the rafters. Arrange the joint between the boards only on the rafters in a run. The nail is sunk completely with the head into the pulp of the wood.

Cornice overhangs

Arranged to protect against precipitation, play an aesthetic role. Eaves overhangs suit tightly without gaps. The final stage in the construction of the roof.

Scheme of the device of the eaves overhang of a gable roof

Gable

The gable roof has two gables. They have the shape of a triangle, with the apex at the ridge and the sides coincide with the slopes of the roof. Gables support the rafters and enclose the attic space. Protect from wind and precipitation, give stability to the roof.

In wooden buildings, the pediment is made frame. In brick buildings, frame or brick. Gables made of brick or gas block are erected before the roofing device. They require very precise execution.

Frame gables fit into the finished opening when the truss system is already assembled.

The frame is made of bars or boards. The frame elements are connected on spikes or to the floor of a tree, all fastened with nails. They are sheathed by nailing boards, lining or siding, maintaining the color in the decoration of the facade of the building. For the device of a window opening, an additional frame is made under it according to the size of the window. If the attic is insulated, then the pediment also needs to be insulated. Insulation is laid in the middle of the frame. A mineral wool insulation with reduced flammability is used. From the outside, the frame is upholstered with a hydro-windproof film or a windproof membrane, from the inside, a vapor-tight film or a vapor-tight membrane is nailed under the finishing material.

Varieties of fastening rafters

hard;
layered;
sliding.

In other options, you will have to make accurate cuts. You will need accurate measuring instruments, a construction pencil and an electric or chainsaw.

The strength of the roof depends not only on how the cuts were made correctly. Consider the following tips:

For rafters, select high-quality materials, since even if you make accurate cuts, the bar may not withstand the load. You can’t save here, because this part takes all the load on itself.
Mounting points with Mauerlat must be free of wood defects, such as knots. Although they are stronger than wood, turbulences form around them, which break at the slightest load.
When installing a roof, do not hesitate to ask for help, as this is a dangerous and responsible business.

A well-made junction of the rafter leg and the Mauerlat guarantees a long service life of the structure.

Cutting out a seat

Before transferring the markup to the rafters, check the accuracy of the finished product. Walk along the roof and check the degree of abutment along the entire length of the Mauerlat. Make adjustments if necessary, but don't expect perfection. Drops of 2-3 mm are acceptable.

The maximum concentration is important so as not to go beyond the outlined boundaries. If you are not confident in your own abilities, then use a hand tool. So you reduce the percentage of marriage and the time for rework.

Finally, check the resulting file with the template and make adjustments if necessary. After that, you can install the finished rafter leg or make seats on the remaining parts.

Cutting for a direct joint with Mauerlat

Knowledge of geometry helps not only in determining the angle of the washed down rafter leg, but also in determining the height of the roof, the length of individual elements, and so on.

J. Carroll (Canada)

BUILD ONE

CONSTRUCTION OF THE ROOF

Building without help is not easy. There you need to support, but here - to squeeze. At the same time, only a magician can be in two or even three places at once. Don't break? The author of this article proves by his example that one person can also build a house. Sophisticated technology, special devices allow you to do this very efficiently. Today he talks about how he erected a roof alone.

The construction of the roof is the most responsible and difficult stage of construction. You have to work at a height, and any kind of fitting is practically impossible here. So, you need to calculate everything well and think over the design so that the installation of the roof becomes less time-consuming.

Work traditionally begins with the preparation of rafters. To do this, I use a template made for specific roof parameters (the angle of inclination of the slopes and the overall dimensions of the building). This device (Fig. 1) allows not only to mark typical cuts on workpieces, but can also serve as a guide when working with a circular saw. The sequence of marking the rafters using a template is shown in fig. 2.

Rice. 1. Template for rafters. Attach with screws

Guide rails are nailed on both sides of the template

with rafters, I begin work with the installation of a ridge run. I assemble support posts for it from two boards. This not only increases the rigidity of the supports, but also simplifies the installation work in the future. Since the boards are knocked down with an offset in height, the ridge beam is securely fixed in the “saddles” of the uprights. I raise the run in stages, and the assistant is replaced by two pairs of L-shaped brackets and clamps (Fig. 4).

I pull the first pair of brackets to the racks at a height of about 1 m from the floor and lay the run on them. So that it does not jump off the shelf, I temporarily fix its free end with another clamp. Then I install the second pair of brackets and raise the ends of the run one by one to a new level. I repeat the process until the bar "sits on saddles".

Having marked the first rafter, then I use a technological rail with control points C, D, E and F transferred to it (Fig. 3). For each subsequent rafter, I first saw the ridge part according to the template, then measure the distance corresponding to the length of the slope, and finally, I apply a technological rail to point C and transfer points D, E and F to the workpiece. It remains only to draw the necessary lines along the template, and the marking is completed .

However, the most time-consuming operations are associated with the installation of the supporting structure of the roof. For pitched roofs

54 Pro Tips #109

Rice. 2. Marking the rafters.

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Step 1. Marking the ridge part of the rafter Attach a template and draw a cut line with a pencil.

Step 2. Marking the length of the slope. Set aside from the bottom point of the ridge cut the distance corresponding to the selected length L of the slope and get point C. Attach the template and draw a line of the horizontal shelf of the tooth with a pencil.

Step 3. Marking the tooth. From point C, set aside on the resulting line the distance corresponding to the thickness S of the beam

the upper strapping of the wall, and then using the template, draw a line parallel to the “ridge” cut through the resulting point A and get point D on the bottom edge of the workpiece. Triangle ACD - rafter tooth.

Cross-sectional template of the frontal board B

Step 4. Marking the overhang of the rafter. At a distance corresponding to the thickness of the outer skin of the wall, draw a line parallel to segment AD and get point E on the bottom edge of the workpiece. Without moving the template, draw a line along the other side of the triangle - this is the lower edge of the rafter overhang. Before lowering the perpendicular to it from the upper edge of the workpiece and getting point B, use the cross-sectional template of the frontal board for sewing the overhangs of the rafters - it must “fit” inside the contour of the workpiece.

One of the difficult moments in the construction of a frame house, which some novice builders stop before, is the question of how to properly make cutouts in the rafters of a house. If you carefully study the material, the experience of experienced builders, it turns out that making them is quite simple.
So that the cutouts in the rafters do not confuse you, I am writing this article.

When writing the article, I relied on an experienced American carpenter. I simply translated some parts of the article, I wrote the technical part in the likeness, but with my own dimensions, in the metric system and without a construction calculator (not everyone has a calculator), plus I slightly changed the counting scheme (because, again, not everyone has a calculator ). For Russian realities, this article has become more adapted.
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Rafter system of a frame house

When I was a young carpenter (or should I say a carpenter's assistant), I admired the skill of roof carpenters. They effortlessly made complex cuts in the rafters of a frame house, knowing only the dimensions of the roof. This puzzled me.
In those years, I tried to repeat their actions, but I failed over and over again. Then the senior carpenter took me with him to one of the roofs and helped me to mark and cut the rafter system with the help of a carpenter's square and the roofer's "Bible" (there is such a very popular book in America, you can buy it on Amazon, Larry Hawn used just such a book in his film - translator's note). This experience inspired me to master the art of making proper cuts in the rafters of frame houses. I can’t say that I have become a master of this business, but I have come a long way and figured out a little how to do it right.

For more comfortable calculations, you will need a construction calculator or a special smartphone application.

Let's move on to measurements

(I'll show you how to calculate everything manually, without a calculator - approx. translator).

Here are the dimensions of the truss system we need: rafter angle(Pitch) climb(Rise) mileage(Run) and diagonal(Diagonal). If you know the dimensions of any two of these four dimensions, you can easily find all the others.

See the video for more details:

(for those who understand English - approx. translator)

Look at our roof model (picture above), initially we need to know the dimensions of two of its elements: building width And ridge board thickness.

The width of the building, for example, will be 8.8 meters. (8.75 meters and sheathing with an inch on each side of the house 0.05m):

Each rafter stands on its own half of the building and is joined to each other on a ridge board. Therefore, from the total width of the building you need to subtract ridge board thickness, otherwise you will make a mistake when calculating the length of the rafter. Let's take its thickness of 50 mm.

We consider the general building width without ridge board: 8.8 meters - 0.05 meters (50 mm) = 8.75 m

Now we need to divide the result by 2 to get "mileage» (Run) of each rafter.
We believe "mileage" each rafter: 8.75m/2 = 4.375m.

Now we need one more element that we know in advance, this is the angle of the roof slope. In our case, let it be 6 to 12 (26.5 degrees- approx. translator).

Since our roof has a slope 6/12 , which means climb we have in two times less, how mileage(because 6 is 2 times less than 12).
We believe climb: 4,375/2 = 2.187m.(half a millimeter rounded)

We believe diagonal:
Run("2) + Rise("2) = Diagonal("2) ("2) - I marked "squared".
19.1406 + 4.7851 = Diagonal("2)
Diagonal= square root of 23.9257
Diagonal = 4,891 = 4 meters 89 cm 1mm

Rafter template.

The next step after the calculations - making a template for rafters. To do this, you need to screw the bosses to your square (it’s more convenient, but you can do without it) at 6 and 12 inches (or 15 and 30 cm in the metric system).

Now I apply the square to the side of the board along its width and begin to mark the place of the cut at the top of the rafter (in junction with the ridge board- approx. translator). Please note that most cuts in frame housing construction are done in this way: the board is cut along the length on the thin side, and in the width in a horizontal position.

I make this saw at the top of the rafter with a circular saw (video) before marking cutout at the bottom of the rafter(so-called "bird's beak" or incoming corner or notch - approx. translator). This is convenient because I can hook the end of the tape measure to the saw at the top and mark the distance on the rafter to the "bird's beak" alone (see the picture below)

Now from the top point of this line we measure the "diagonal" 4 meters 89 cm 1mm.

Then, using a regular carpenter's square (some carpenters prefer the Swanson protractor square, you can read about it on the forum - approx. translator), I draw a parallel line to the first saw across the rafter. This line represents the plumb line (i.e., parallel to the wall and perpendicular to the floor of the frame house) on the rafter at the edge of the building.

How to draw such a line on the Swanson alternative square, the following short video will show:

I personally love my Swanson square very much, it has been my faithful assistant in construction from the very first days.

So, "bird's beak" starts from this line. If you are building and you have clear dimensions of rafters and cuts (project), you must select at this stage the size of the horizontal cutout, the plane of the rafter, which lies on the ceiling (see the bottom photo on the bottom left). Canadian codes require this saw to be at least 38 mm.

The horizontal dimension should be such that the rafter is not greatly weakened, i.e. the cut did not go further than a third of the board (see figure below).

According to the author, this is the fastest way to mark this cut (pictured above). To do this, you need to turn the square 90 degrees to the previous saw and press the bosses to the board, while slowly leading the square towards the top of the rafters, until the required distance from the drawn line and the angle of the board in the direction of the square (in the original was 4 inches).
There is another method (pictured below).
We apply the square to the drawn line and move the square along the vertical line until the desired mark of the horizontal scale (110-120 mm) touches the edge of the board.

Let's look at our case.

Let's take for example that we have rafters from a board 200×50mm. For her, with a roof slope angle of 6 to 12, it will be safe to make a horizontal cut 120 mm. In this case, vertically taken away from the board 60mm(since with such a slope we always have a vertical size 2 times smaller than the horizontal one, remember?) and the rafter will definitely not be weakened.
And here are interesting estimates for cuts at different angles and different board widths (according to one authoritative frame builder from the forum):

We consider the "rise" in reality.

Yes, we already have the "rise" size and it is equal to 2.1875 meters. But let's look at our scheme of the truss system. Obviously, our size is not the same as the board that supports the skate (even if only temporarily).

First we need to add to our "rise" the so-called H.A.P., which is equal to the size remaining vertically above the wall trim under the bottom of the rafters, where we made a vertical cut (pictured above).

We believe our H.A.P: 223.6mm (full width of the board at 26.57 degrees) subtract 60mm (our vertical cutout) = 163 mm.

Now to our rise (2.1875 meters) add H.A.P ( 0.1635 m), it turns out 2.35 m.

We ended up at the highest point of convergence of the rafters at the ridge board. But we don't need her. Now we finally get the height of the desired board for the ridge board.

Height skate boards: 2.35 m subtract the height of the ridge board 200 mm = 2.15 m, i.e. 2 m 15 cm.

Find the full length of the rafters.

After all this mess, I would like to know the length of the TOTAL rafter, i.e. with eaves. Everything is simple here.

For example, we need overhang 80 cm, this means that with a roof of 6 to 12, the overhang lowers down by ½ of the length of the overhang, i.e. 0.4 meters.

We believe overhang diagonal= 0.16 (0.4 squared) + 0.64 (0.8 squared) = 89.5 cm

Total full length of each rafter with overhang = 4 meters 89 cm 1mm + 89 cm 5 mm = 5 meters 78 cm 6 mm.

A small bonus to the text.
square Swanson deserves a separate video (below). And for those who are imbued with it and decide to buy it, be sure to have at hand a translation of the book that comes with it on sale in English. language.

So, I hope, after reading this article, it has become much clearer to you how to make cutouts in the rafters of your frame house. If you have any more questions, get in touch.

How the site can help you

1. Make it convenient and understandable for you (or help in designing a frame house).

4. Bring you from Belarus

5. 1. Consult on any issue of frame housing construction. 1 hour - 1000 rubles(or 2 weeks of answers in text format also for 1000 rubles)

You can contact me via email or phone +79200221811

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