Installation of a gable roof with hanging rafters. Roof truss system and features of its design

Roof installation is a complex multi-step process. To independently assemble and install a rafter system, you need to carefully study the methods of connecting elements, calculate the length of the rafters and the slope angle, and select the appropriate materials. If you don’t have the necessary experience, you shouldn’t take on complex designs. The best option for a small residential building - a do-it-yourself gable roof.

A standard roof of this type consists of the following elements:

Mauerlat is a timber laid on top of the walls along the perimeter of the building. It is secured using threaded steel rods embedded in the wall or anchor bolts. The timber must be made of coniferous wood and have a square section of 100x100 mm or 150x150 mm. The Mauerlat takes on the load from the rafters and transfers it to the external walls.

Rafter legs- these are long boards with a cross section of 50x150 mm or 100x150 mm. They are attached to each other at an angle and give the roof a triangular shape. The structure of their two rafter legs is called a truss. The number of trusses depends on the length of the house and the type of roofing. Minimum distance between them is 60 cm, the maximum is 120 cm. When calculating the pitch of the rafter legs, you should take into account not only the weight of the covering, but also the wind load, as well as the amount of snow in winter.

It is located at the highest point of the roof and most often represents a longitudinal beam connecting both slopes. The beam is supported from below vertical racks, and the ends of the rafters are attached to the sides. Sometimes the ridge consists of two boards that are nailed to the top of the rafters on both sides and connected at a certain angle.

Racks are vertical bars with a cross section of 100x100 mm, located inside each truss and used to transfer the load from the ridge run to load-bearing walls inside the house.

The struts are made from scraps of timber and installed at an angle between the posts and rafters. The side edges of the truss are strengthened with braces and the load bearing capacity designs.

Tie - a beam connecting the lower parts of the rafters, the base of the truss triangle. Together with the struts, such a beam serves to strengthen the truss and increase its resistance to loads.

A log is a long beam with a cross-section of 100x100 mm, laid along the central load-bearing wall, on which vertical posts rest. Lezhen is used when installing layered rafters when the run between the outer walls is more than 10 m.

The sheathing consists of boards or timber placed on the rafters. The sheathing can be continuous or with gaps, depending on the type of roof. It is always attached perpendicular to the direction of the rafters, most often horizontally.

If there is no more than 10 m between the external walls and there is no load-bearing wall in the middle, arrange hanging rafter system. With this system, the upper ends of adjacent rafters are sawn at an angle and connected to each other using nails, excluding the installation of racks and ridge beams. The lower ends of the rafter legs rest on the external walls. Due to the absence of racks, attic space can be used to furnish an attic. Very often, the function of tightening is performed by floor beams. To strengthen the structure, it is recommended to install the top tie at a distance of 50 cm from the ridge.

If there is a central supporting wall, the arrangement is more justified layered rafter system . A bench is laid on the wall, support posts are attached to it, and a ridge beam is nailed to the posts. This installation method is quite economical and easier to implement. If the ceilings are interior spaces are designed at different levels, racks are replaced brick wall, dividing the attic into two halves.

The roof installation process includes several stages: attaching the Mauerlat to the walls, assembling the trusses, installing the rafters on the floors, installing the ridge, and attaching the sheathing. All wooden elements Before assembly begins, they are thoroughly treated with any antiseptic composition and dried in air.

To work you will need:

• timber 100x10 mm and 150x150 mm;
• boards 50x150 mm;
• boards 30 mm thick for lathing;
• roofing felt;
• metal studs;
• jigsaw and hacksaw;
• hammer;
• nails and screws;
• square and building level.

In wooden houses the functions of the mauerlat are performed by logs last row, which greatly simplifies the workflow. To install the rafters, just cut inside log grooves of the appropriate size.

IN brick houses or buildings made of blocks, installation of the Mauerlat occurs as follows:

The mauerlat bars must form a regular rectangle and be in the same horizontal plane. This will facilitate further installation of the roof and provide the structure with the necessary stability. Finally, markings are made on the beams for the rafters and grooves are cut along the thickness of the beam.

When choosing a hanging rafter system, it is necessary to assemble the trusses on the ground and then install them above the floors. First you need to draw up a drawing and calculate the length of the rafter legs and the angle of their connection. Typically, the roof slope is 35-40 degrees, but in open, heavily blown areas it is reduced to 15-20 degrees. To find out at what angle to connect the rafters, you should multiply the angle of the roof by 2.

Knowing the length of the run between external walls and the angle of connection of the rafters, you can calculate the length of the rafter legs. Most often it is 4-6 m, taking into account the eaves overhang 50-60 cm wide.

The upper ends of the rafters can be fastened in several ways: overlapping, end-to-end and “into the paw”, that is, with grooves cut out. Metal plates or bolts are used for fixation. Next, the lower and upper ties are installed, and then the finished trusses are lifted up and installed above the floors.

The outer trusses are attached first: using a plumb line, the rafters are aligned vertically, the length of the overhang is adjusted and attached to the mauerlat with bolts or steel plates. To prevent the truss from moving during installation, it is reinforced with temporary beams made of timber. After installing the outer rafters, the rest are set, keeping the same distance between them. When all the trusses are secured, take a board with a cross-section of 50x150 mm, the length of which is 20-30 cm longer than the length of the cornice, and nail it along the upper edge of the slope. The same is done on the other side of the roof.

The first option: a rectangular groove is cut out on the rafter leg at the point where it touches the mauerlat, 1/3 of the width of the beam. Stepping back 15 cm from the top of the box, a steel spike is driven into the wall. The rafter is leveled, the grooves are aligned, then a wire clamp is placed on top and the beam is pulled close to the wall. The ends of the wire are securely fastened to the crutch. The lower edges of the rafters are carefully cut off circular saw, leaving an overhang of 50 cm.

Second option: the upper rows of walls are laid out with a stepped cornice of bricks, and the mauerlat is placed flush with the inner surface of the wall and a groove is cut out in it for the rafter. The edge of the rafter leg is cut to the level of the upper corner of the cornice. This method is simpler than others, but the overhang is too narrow.

Third option: beams ceilings are released over the edge outer wall by 40-50 cm, and the trusses are installed on the beams. The ends of the rafter legs are cut at an angle and rest against the beams, secured with metal plates and bolts. This method allows you to slightly increase the width of the attic space.

Installation of layered rafters

Figure 1 shows the cutting of rafter struts into a beam laid on intermediate supports, and Fig. 2 - resting the rafter leg on the mauerlat

The procedure for installing a layered rafter system:

When the main elements are fixed, the surface of the rafters is treated with fire retardants. Now you can start making the sheathing.

For the sheathing, timber 50x50 mm is suitable, as well as boards 3-4 cm thick and 12 cm wide. Waterproofing material is usually laid under the sheathing to protect the rafter system from getting wet. The waterproofing film is laid in horizontal strips from the eaves to the roof ridge. The material is spread with an overlap of 10-15 cm, after which the joints are secured with tape. The lower edges of the film should completely cover the ends of the rafters.

It is necessary to leave a ventilation gap between the boards and the film, so first stuff them onto the film. wooden slats 3-4 cm thick, placing them along the rafters.

The next stage is covering the rafter system with boards; they are stuffed perpendicular to the slats, starting from the roof eaves. The pitch of the sheathing is influenced not only by the type of roofing, but also by the angle of inclination of the slopes: the greater the angle, the greater the distance between the boards.

After completing the installation of the sheathing, they begin cladding the gables and overhangs. You can cover the gables with boards, plastic panels, clapboard, waterproof plywood or corrugated sheeting - it all depends on financial capabilities and personal preferences. The sheathing is attached to the side of the rafters; nails or screws are used as fasteners. Overhangs are also hemmed various materials– from wood to siding.

Video - DIY gable roof

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

Picture 1

I think it is obvious to everyone that with such an arrangement, bursting loads appear on the walls. To reduce them, tie downs are added to the 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/m2. 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, pushing forces will act on it, tending to move it from the wall. For more reliable fastening, you can add metal fastening plates to the anchor bolts (or studs) (see Fig. 3). The plates can be secured to the wall, for example, with frame anchors, and to the Mauerlat using nails, self-tapping screws, and wood grouse.

Figure 3

STEP 2: We determine the required section of the rafters. We carry out the calculation in the “Arch” tab (see Fig. 4):

Figure 4

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

A question may immediately arise here. Where do we get the distance from the ridge to the tie rod? For us it is 2 meters. Earlier on the site, we already said that before we start building a roof, we need to make a drawing of it on paper, always to scale (with all proportions respected). If you know how, you can draw on the computer. Further, using this drawing, we determine all the dimensions and angles that interest us.

Tie-downs are installed between hanging rafters to reduce bursting loads on the walls. The lower the tension, the more benefit it will provide. Those. the less bursting load there is on the walls. But since in our example the tie rods also serve as ceiling beams for the attic floor, we determine the height of their location based on the ceiling height we need. I took this height of 2.5 meters (see Fig. 5):

Figure 5

STEP 3: We make a template for the lower cut of the rafters. To do this, we take a piece of board of the desired section about a meter long, apply it to the mauerlat at our angle of inclination of the slopes of 40° (focus on the pediment) and make markings, as shown in Figure 6:

Figure 6

The vertical and horizontal lines(shown in blue) are carried out using a level. The depth of the cut is 5 cm.

So, let's make a template.

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

We take the template we 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 lowest 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

Right bottom corner Let's designate it as point "B". Now we can measure the distance from the attic floor to point B (the length of the temporary racks).

We install strictly vertically temporary racks from 50x200 boards and place a ridge board of the same section on them. To fix them, you can put a board under the posts, secured with simple dowel nails to the floor slabs (see Fig. 9). There is no need to fasten it too much, then we will remove it. The distance between the posts is no more than 3 meters.

Figure 9

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

Perhaps you could see somewhere how hanging rafters are installed without a ridge board (see figure on the left). I am very familiar with this method; we did this before 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 ridge boards, subsequent installation of the rafters is much more convenient and faster. As a result, in time you win. In addition, the design is more stable and more geometrically smooth.

STEP 5: We manufacture and install rafters.

We make a rafter like this: we take a board of the required length, apply a template to one end, mark it and make the bottom cut. Then use a tape measure to measure the distance between points “A” and “B” (see Fig. 7-8). We transfer this size to our workpiece and make the top cut. The angle we need for the top cut is on our template (see Fig. 10). For us it is 90°+40° = 130°

Figure 10

This is how we install 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 already understand that this is due to the presence of bursting loads, which were not present 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 also use cuts that are more familiar to us. The main thing is to securely fasten the rafters to the Mauerlat.

At the top point, the rafters will protrude beyond the ridge board. You can drive small bars between them, or you can leave them 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 seem to be sandwiched between the Mauerlat and the ridge board.

STEP 6: We install the tightening.

We make them from boards of the same section as the rafters. It is not necessary to make any cuts or cuts here. We make the puffs overlapping the rafters. We fasten them with several nails and tighten them with a threaded rod with a diameter of 12-14 mm (see Fig. 13):

Figure 13

Thus, we install all the tightening and remove our temporary stands on which we placed the ridge board:

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 semi-attic floor (between the puffs).

STEP 7: We attach the eaves overhang fillets 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 that we get the eaves 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 rods. In the middle part, for additional support on the wall, you can fasten a small block to the fillet with nails or self-tapping screws.

Figure 15

Please note that at the junction of the overhang fillet with the mauerlat, we do not make a cut on it, because this will reduce its already small cross-section. Here we first make a small cut in the Mauerlat itself (see Fig. 16):

Figure 16

To make the cornice even, use lace. Place the outer fillies first, then pull the string between them and place the rest. In Figure 17, the lace is shown in blue.

Figure 17

Step 8: We already know the following steps from previous articles. We place the fillies on the pediment and attach the wind boards (see Fig. 18):

Figure 18

STEP 9: Now we can leave the cornices as they are.

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

Figure 19

These “earrings” are made from inch boards 10-15 cm wide. We fasten them with self-tapping screws.

Thus, now all we have to do is hem the siding belts to the bottom of the eaves; secured to the rafters protective film, make counter-lattice and sheathing; cover the roof with roofing material. We discussed these steps in previous articles. I think there is no point in repeating myself here and when considering other roof designs in the future.

Every day new houses appear on earth, which are built according to absolutely different technologies. Through trial and error, people choose for themselves optimal design, which will serve them for a long time and efficiently. The choice of roof construction system is one of the most important issues resolved in the process of designing a house. Currently, the roof truss system, which has been used for quite a long time and has many advantages, is becoming in demand.

The rafter system is called load-bearing structure roof, which is the basis for the tightness of the roof and the stability of the walls. That is, how durable the house will be depends on the quality work done in this direction. This is a roof frame, which consists of a number of interacting parts.

Elements of the roof truss system

It's pretty complex design, and the importance of each of its constituent parts should not be underestimated. Here's what it's usually made from:

1. Rafter, or rafter leg. This is a beam that is used to form the angle of inclination of the entire roof. In addition, the rafter is also a support for the roof. The choice of material from which the rafter leg will be made must be taken seriously, because it will be affected by the wind, the weight of people, and precipitation. Therefore, these elements of the rafter system are made from boards with big size sections, especially in the vertical direction.
2. Puff. This is a beam or board connecting the rafters, which are located on opposite slopes. It is located horizontally and does not allow the rafters to creep apart.
3. Run. This is a beam that serves as a support for the rafters at the top or in the middle.
4. Rack. This element is used to support the purlin or rafters. A rack is a component of the system, located vertically; walls often serve as support for it.
5. Mauerlat. This is the beam most often square shape, support for the lower part of the rafters. Mauerlat is laid along the entire perimeter of the building on the walls.
6. Wind beam. This element connects the rafters to each other, forming a roof slope. We are talking about a board that is attached at an angle to the rafters from the attic. The wind beam prevents the rafters from moving in strong winds.
7. Strut. The roof rafter system requires the presence of timber, which should support the rafters so that they do not sag. The strut is attached at an angle to the vertical elements of the building.
8. Sprengel. This is a beam made of logs or timber, thanks to which the entire structure is strengthened. Its location is horizontal. The sprengel is located on adjacent walls; it would be correct to install it perpendicular to the bisector of the angle that these walls create.
9. Filly. This is a board that is attached to the rafters, namely to their lower part. The main role of this element is to create an overhang of the roof.
10. Narozhnik. This is a rafter, but shortened, resting on one side on the mauerlat, and the other on the diagonal leg.

Features of the gable roof rafter system

A gable roof is the most common type of roof for houses up to 3 floors inclusive. Installing such a roof is not at all difficult; you can do it yourself. This installation of the rafter system assumes the presence of two rectangular planes inclined towards each other, which make the upper part of the structure triangular.

Gable roofs mainly consist of rafters and mauerlats. There are layered and hanging rafter systems of this type of roof. With a layered system rafter legs cover the roof and have a span of up to 7 m. If it is necessary to cover a larger span, they resort to installing intermediate supports, which increases the length of the span to 12-15.5 m. Layered rafters have supports on the top of the walls or on the crown of the log house. The middle and lower parts of the rafter legs serve as support.

A suspended roof truss system is a structure in which the rafters rest on load-bearing walls, with no intermediate beams. This type of roofing is acceptable for houses in which the walls are made of lightweight material. The advantage of the hanging system is this: it is excellent for forming long spans. To make the structure strong, purlins, struts, and racks are used.

Rafter system of a hipped roof: advantages and disadvantages

The hip roof is one of the most popular for modern private houses. It has a number of advantages:

• hurricane resistance;
• resistance to deformation;
• good protection of building facades from precipitation;
• beauty of appearance.

However, there are also disadvantages of such a rafter system:

• the design is more expensive than a gable one;
• slopes reduce the area of ​​the attic;
• It is very difficult to install a four-slope rafter system yourself.

Main fastenings of the roof rafter frame

To know how to properly make a roof frame, you need to understand what the main components of the rafter system are. The main nodes are as follows:

1. Attachment point to the beam. The rafter leg must be attached to the beam using a tooth with a tenon (in the rafter) and a socket (in the beam). In this case, the nest should have a depth that will be 25-30% of the volume of the beam. If we are talking about a roof with an angle of less than 35°, a knot with two spikes is used. To create the structure, metal screws, nails, angles, bolts, as well as wooden scarves, tenons and beams are used.
2. Mounting point to the Mauerlat. For fastening, a cut or saddle is made on the rafter, then the connection is fixed using nails, staples and wire. Two nails are crossed together, and the third is forgotten between them in the center. This is how the rafters are attached gable roof and Mauerlat.
3. Ridge connection unit. Can be mounted end-to-end, overlapping and on ridge beam. Most often this is done with an overlap, in this case the rafter legs touch each other not with their ends, but with their planes. Fastening occurs using a pin, nails or bolt.

Video with errors during the construction of the rafter system. You can't build like this:

An example of calculating the rafter system of a conventional gable roof

It is quite possible to build a rafter roof yourself; it is important to be able to correctly calculate the amount of materials needed for this work, as well as take into account all the essential nuances.

Need to consider specific example calculating the roof truss system, and then everything will become completely clear. So, let’s take a house 4 m wide and 6 m long. In this case, the angle of inclination of the rafters is 120°. It will be implemented that there is 1 m between the rafters. 0.5 is the allowance for the roof canopy.

• Find the height of the central support: 0.5x(Width of the house)/tgY/2=0.5x4/1.73=1.2 m.
• Calculate the length of the rafter leg. The size of the rafters for the roof is: 0.5x(Width of the house)/sinY/2+0.5=2.8 m.
• Roof area: (House length)x(Rafter length)x2=33.6 m². This is the number of sheets of metal tiles you will need for the roof.
• Let's calculate the length of the beam: 2x(Length of the rafter leg)+(Width of the house)+(Height of the central support)=75.5 linear meters.
• Since the length of the house is 6 m and the distance between the rafters is 1 m, it will be necessary to have 7 rafters.

Installation of rafters

You should start working with beam floors. To understand how to install rafters on the roof, you need to understand the installation options. If you do not plan to use the attic as housing, you can take 50x150 mm boards. If you need to make an attic, you need a 150x150 mm beam, which will be installed on the load-bearing walls of the house.

The rafter installation process involves the following steps:

1. Preparation of structural elements. To do this, boards and beams of the required size are made using a circular saw.
2. Marking of all components of the structure according to templates.
3. Assembling the roof truss system according to the markings. After completing this work, all elements should be marked.
4. Sockets are selected in rafter legs and other elements. All fastenings are made using nails, screws, self-tapping screws, metal corners, dowels and wire.

Rafters with small spans can be assembled off-site at special enterprises and purchased in this form. Thanks to this, the roof frame is made much faster.

It is not for nothing that the rafter system is chosen for roof installation, because it is simple and reliable. Knowing the algorithm of actions, you can create a durable roof that will protect from wind, cold and precipitation.

Video on installing the rafter system:

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, absorb atmospheric loads, and hold the material. Among the rafter's duties are the formation of smooth planes for laying the covering and providing space for the components of the roofing pie.

In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information is needed about the rules and principles of its design. The information is useful both for those who are constructing a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

In device rafter frame For pitched roofs use wooden and metal beams. Source material For the first option, use a board, log, timber.

The second is constructed from rolled metal: channel, profile pipe, I-beam, corner. There are combined structures with the most heavily loaded steel parts and wood elements in less critical areas.

In addition to its “iron” strength, metal has many disadvantages. These include thermal qualities that are unsatisfactory to the owners of residential buildings. The need to use welded joints is disappointing. Most often, industrial buildings are equipped with steel rafters, and less often, private cabins assembled from metal modules.

In business self-construction Wood is the priority for rafter structures for private houses. It is not difficult to work with, it is lighter, “warmer”, and more attractive in terms of environmental criteria. In addition, to perform nodal connections you will not need welding machine and welding skills.

Rafters - a fundamental element

The main “player” of the frame for constructing a roof is the rafter, which among roofers is called a rafter leg. Beams, braces, headstocks, purlins, ties, even a Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

Rafters used in the construction of gable roof frames are divided into:

• Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests against the mauerlat or the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of the adjacent rafter or a purlin, which is a beam laid horizontally under the ridge. In the first case, the rafter system is called spacer, in the second, non-spacer.
• Hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - a tie. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a rafter truss. Tightening dampens the tensile processes, so that only vertically directed load acts on the walls. Although a structure with hanging rafters is braced, the bracing itself does not transmit to the walls.

In accordance with the technological specifics of rafter legs, the structures constructed from them are divided into layered and hanging. For stability, the structures are equipped with struts and additional racks.

To support the top of the layered rafters, planks and purlins are installed. In reality, the rafter structure is much more complex than the elementary templates described.

Note that the formation of the frame of a gable roof can generally be done without a rafter structure. In such situations, the supposed planes of the slopes are formed by slabs - beams laid directly on the load-bearing gables.

However, we are now interested specifically in the structure of the rafter system gable roof, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

Fastening the rafter system to brick, foam concrete, aerated concrete walls is carried out through the Mauerlat, which in turn is fixed with anchors.

Between the Mauerlat, which is wooden frame, and walls made of the specified materials in mandatory a waterproofing layer of roofing material, waterproofing material, etc. is laid.

The top of brick walls is sometimes specially laid out so that along the outer perimeter there is something like a low parapet. This is so that the mauerlat placed inside the parapet and the walls do not push apart the rafter legs.

Roof frame rafters wooden houses rest on the upper crown or on ceiling beams. The connection in all cases is made by notches and is duplicated with nails, bolts, metal or wooden plates.

How to do without mind-boggling calculations?

It is highly desirable that the cross-section and linear dimensions of wooden beams be determined by the project. The designer will provide clear calculation justifications geometric parameters boards or timber, taking into account the entire range of loads and weather conditions. If available home handyman there is no design development, its path lies on the construction site of a house with a similar roofing structure.

You don’t have to pay attention to the number of floors of the building being constructed. It is easier and more correct to find out the required dimensions from the foreman than to find out them from the owners of a shaky self-built building. After all, in the hands of the foreman is documentation with a clear calculation of the loads per 1 m² of roof in a specific region.

The installation pitch of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For styling clay tiles, For example, optimal distance between the rafters there will be 0.6-0.7 m, and for corrugated sheets 1.5-2.0 m is acceptable.

However, even if the pitch required for proper installation of the roof is exceeded, there is a way out. This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to understand the pitch of the rafters before constructing the rafter system.

Craftsmen calculate the pitch of the rafters according to design features buildings, simply dividing the length of the slope into equal distances. For insulated roofs, the pitch between the rafters is selected based on the width of the insulation slabs.

You can find it on our website, which may also help you a lot during construction.

Rafter structures of layered type

Layered rafter structures are much simpler to construct than their hanging counterparts. A reasonable advantage of the layered scheme is to ensure adequate ventilation, which is directly related to long-term service.

Distinctive design features:

• It is mandatory to have support under the ridge heel of the rafter leg. The role of support can be played by the run - wooden beam, resting on racks or on the internal wall of the building, or the upper end of an adjacent rafter.
• Using a Mauerlat to erect a truss structure on walls made of brick or artificial stone.
• The use of additional purlins and racks where the rafter legs, due to the large size of the roof, require additional support points.

The disadvantage of the scheme is the presence structural elements, affecting the layout of the internal space of the used attic.

If the attic is cold and it is not intended to organize useful rooms, then the layered structure of the rafter system for installing a gable roof should be given preference.

Typical sequence of work for the construction of a layered truss structure:

• First of all, we measure the heights of the building, the diagonals and horizontality of the upper cut of the frame. When identifying vertical deviations of brick and concrete walls, we eliminate them cement-sand screed. Exceeding the heights of the log house is cut off. By placing wood chips under the mauerlat, vertical flaws can be combated if their size is insignificant.
• The floor surface for laying the bed must also be leveled. It, the Mauerlat and the girder must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
• We process everything wooden parts structures before installation with fire retardants and antiseptics.
• On concrete and brick walls We lay waterproofing under the installation of the Mauerlat.
• We lay the mauerlat beam on the walls and measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the ideal geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The beams are joined into a single frame using oblique notches; the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fastening is done either with staples to wooden plugs installed in advance in the wall, or with anchor bolts.
• Mark the position of the prone position. Its axis should recede from the mauerlat bars at equal distances on each side. If the run will rest only on posts without supports, we carry out the marking procedure only for these posts.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, with internal wall We connect with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut out the racks to uniform sizes, because... Our bed is exposed to the horizon. The height of the racks should take into account the cross-sectional dimensions of the purlin and beam.
• We install racks. If provided by the design, we secure them with spacers.
• We lay the purlin on the racks. We check the geometry again, then install brackets, metal plates, and wooden mounting plates.
• We install a test rafter board and mark the cutting areas on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the rafters on the roof after the fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. For marking, folk craftsmen usually prepare a pair of slats, the length of which is equal to the clearance between the rafters.
• According to the markings, we install the rafter legs and fasten them first at the bottom to the mauerlat, then at the top to the purlin to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is made flawlessly, the layer boards are installed in any order.

If there is no confidence in the ideal structure, then the outer pairs of rafters are installed first. A control string or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the rafter structure is completed by installing fillets, if the length of the rafter legs does not allow forming an overhang of the required length. By the way, for wooden buildings the overhang should extend beyond the contour of the building by 50 cm. If you plan to organize a canopy, separate mini-rafters are installed under it.

Another useful video about building a gable rafter base with your own hands:

Hanging rafter systems

The hanging variety of rafter systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the base is the tie connecting the lower heels.

The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the sheathing, roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging rafter structures.

Specifics of hanging rafter systems

Characteristic features of hanging type rafter structures:

• The obligatory presence of a tie, most often made of wood, less often of metal.
• Possibility to refuse to use the Mauerlat. A timber frame can be successfully replaced by a board laid on double-layer waterproofing.
• Installation of ready-made closed triangles – trusses – on the walls.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages.

The first of them is restrictions on the steepness of the slopes: their slope angle can be at least 1/6 of the span triangular truss, steeper roofs are strongly recommended. The second disadvantage is the need for detailed calculations for the proper installation of cornice units.

Among other things, the angle of the truss will have to be installed with pinpoint precision, because the axes of the connected components of the hanging rafter system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the backing board replacing it.

Subtleties of long-span hanging systems

The tie is the longest element of a hanging rafter structure. Over time, as is typical for all lumber, it becomes deformed and sags under the influence of its own weight.

Owners of houses with spans of 3-5 m are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional details, excluding geometric changes in tightening.

To prevent sagging, there is a very significant component in the installation diagram of the rafter system for a long-span gable roof. This is a pendant called a grandmother.

Most often it is a block attached with wooden pegs to the top of the truss. The headstock should not be confused with the racks, because its lower part should not come into contact with the puff at all. And installation of racks as supports in hanging systems ah does not apply.

The bottom line is that the headstock hangs, as it were, on the ridge assembly, and a tightening is attached to it using bolts or nailed wooden plates. To correct sagging tightening, threaded or collet-type clamps are used.

The tightening position can be adjusted in the area of ​​the ridge assembly, and the headstock can be rigidly connected to it by a notch. Instead of a block on non-residential attics For the manufacture of the described tension element, reinforcement can be used. It is also recommended to install a headstock or hanger where the tie is assembled from two beams to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the proper placement of vector loads acting on the system.

As a result, the rafter system is stable with minor and not too expensive modernization.

Hanging type for attics

In order to increase usable space the tightening of the rafter triangles for the attic is moved closer to the ridge. A completely reasonable move has additional advantages: it allows you to use the puffs as a basis for lining the ceiling.

It is connected to the rafters by cutting with a half-pan and duplicating with a bolt. It is protected from sagging by installing a short headstock.

A noticeable disadvantage of the hanging attic structure is the need for accurate calculations. It is too difficult to calculate it yourself; it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of rafter systems cannot be the same, because:

• In the construction of a layered structure, a board or beam of small cross-section is used to make rafter legs. Because layered rafters have two reliable supports underneath them; the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, the rafters are made of thick timber. To make a tightening, a material with a similar cross-section is required. Even taking into account the abandonment of the Mauerlat, the consumption will be significantly higher.

It will not be possible to save on the grade of material. For the load-bearing elements of both systems: rafters, purlins, beams, mauerlat, headstocks, racks, 2nd grade lumber is needed.

For crossbars and tensile ties, grade 1 will be required. In the manufacture of less critical wooden overlays, grade 3 can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used in greater quantities.

Hanging trusses are assembled in an open area next to the facility, then transported to assembled form up. To lift weighty triangular arches from timber, you will need equipment, the rental of which will have to be paid. Yes, and a project for complex nodes The hanging option is also worth something.

Video instruction on the installation of a hanging category truss structure:

There are actually many more methods for constructing rafter systems for roofs with two slopes.

We have described only the basic varieties that are actually applicable for small country houses and buildings without architectural tricks. However, the information presented is enough to cope with the construction of a simple truss structure.

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It's hard to imagine a house without a roof. Without it, the house cannot be called complete. The roof, as you know, protects the house from precipitation, inclement weather, etc. In addition, it is used to complete the architectural image of the constructed object. In this case, it is necessary to correctly calculate and install roofing system, only then will the roof last long years, and it will not need to be repaired every year.

The structure of the rafters can be very different. We propose to consider their most common types and types, methods of their fastening.

As you know, the roof can be flat or pitched. Concerning suburban construction, then in this case the installation of a gable roof rafter system is especially popular. If the house is very large, then the roof will be of the appropriate size, for example, hipped (more details: ""). Thus, the developer must imagine the design of the rafter system hipped roof. The most simple option the device of the rafter system is considered pitched roof, since it is very labor-intensive and requires sufficient knowledge.

Still, it is worth noting that the installation of a gable roof rafter system is considered the most common option today. The design consists of two planes that are on the same level. They are also the load-bearing part that rests on the walls of the house. Usually there is an attic under the roof slopes. If it is heated, then it can be used as an attic floor where you can arrange a functional room.

It is worth noting that from roofing material The angle of inclination of the future roof will depend. It is usually measured in degrees.

Determining the reliability of the rafter system

When installing a roof, developers pay special attention to the rafter system. It must be made reliable, because the service life of the roofing structure depends only on this system.

The reliability of the rafter system is usually affected by the following points:

Construction of a rafter roof: structural components

We can conclude that if the rafter system is calculated incorrectly and unprofessionally, it may simply not withstand the load in the future. In this case, terrible consequences cannot be avoided.

When calculating the design of the rafter system, the following points must be taken into account:

• roof shape;
• location of internal supports;
• floor span size;
• expected operating loads.

In the design of the rafter system, the triangle is the main figure. Rafter legs are also important in similar design, their design must be given maximum attention. They are usually laid along the roof slope. The sheathing is supported precisely by the rafter legs.

What types of rafters are there?

Today rafters can be:

• hanging;
• layered.

Sami optimal sections there will be the following options:

• for boards – 16-18x4-5 cm;
• for bars – 16-18x12-14 cm;
• for round timber – 12-16 cm.

The axis distance between the bars and logs should be 150-200 centimeters. The distance of the rafters between the beams of the boards is usually 100-150 centimeters.

At the end of each rafter leg, so-called fillies must be nailed. To complete them regular one will do board. Along the entire cornice along the slope of the filly, you need to nail the formwork, which will serve as the base for the boardwalk. It is on this decking that the roof material is attached.

The installation of a rafter system for a gable roof or any other may encounter such a difficulty as expansion (read: ""). To avoid expansion of the rafter system, the rafters must be attached to the ridge very firmly.

If the device is used incorrectly, displacement of the ramp may also occur. If you cut the rafter legs into the wood floor, this will not happen. The strength of the joint can also be achieved with an overlay, or with reliable fastenings, which are made using bolts and dowels.

In this case, you need to take the calculation especially seriously maximum load roofs, and we must not forget about the snow cap. Price roofing works in this case, it will increase significantly, since more lumber will be required, and the tiles themselves are not cheap.

Because of such high costs many people choose soft roof covering. In this case, you need to remember about the sheathing, which is made entirely of boards or plywood. This type of roof also requires underlay carpets. Therefore, when purchasing, the developer building materials You will also have to pay quite a bit of money.

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