Do-it-yourself gable roof rafters - making the right frame with the right calculations. How to properly make a gable roof truss system with your own hands Schemes of a gable roof truss system

This is roughly how the Mauerlat is fixed:

This is how the rafters are attached with pre-drilling:

This is how the sheathing is attached:

One of the simplest roofing structures- this is a gable roof: even a non-specialist can build it with his own hands. How to calculate the structure and build a roof frame? At one time I had to master the technique of building such roofs. I will share my experience with you.

Types of rafter systems

The gable roof is one of the most ancient. It is represented by two flat slopes that meet at the top along one line. The lower edges of the slopes rest on the walls of the house, which are usually at the same level.

The end parts of the roof of gable structures are two vertical triangles-pediments. The pediment can be made of the same material as the walls, or made separately. In the second case, it is made thinner, or materials with less mass are used - this way the load on the base can be reduced.

Roof slopes can be located at different angles. If the angle is large enough, then you can build an attic space under the roof. With a slight slope, the under-roof space turns out to be low, and it is used, at best, as an attic.

A gable roof with different slopes is also possible. As a rule, it is built when it is necessary to connect two walls of different heights or when installing two slopes with different angles of inclination.

The basis gable roof - rafter system, which can be of two types:

Layered rafters are made when the house has a central load-bearing wall. At its end there are racks on which the purlin is attached. It is this purlin that serves as support for the upper ends of the rafter legs, which form the slopes. Sometimes, instead of racks, a full-fledged supporting wall is erected - but this option is only suitable for houses on a massive foundation.

If the central load-bearing wall is not in the middle of the building, then you will have to make a roof with a displaced ridge and slopes of different sizes, located at different angles.

Hanging rafters installed in the absence of a central supporting structure. The rafter legs are connected to each other without a top purlin, resting on each other (and on the ridge beam). To increase rigidity, intermediate elements are added to the structure - tightening and overlays, which prevent the rafter legs from moving apart.

The choice of rafter system is determined precisely by the design of the building itself:

there is a middle wall- we make a layered structure;
no wall- we install hanging rafters.

Calculation of rafters for a gable structure

The most important stage of the work is calculating the basic parameters of the future roof frame. There are three ways you can go here:

Use a ready-made solution, making the rafter system an exact copy of the frame of the already constructed roof. Ideal for standard homes, but find suitable option It is not always possible to copy.
Use an online calculator for calculation truss structure. Option suitable for preliminary calculation and assessments various options. The calculators I have worked with are quite accurate, but there is a risk of not taking something into account.

Carry out the calculations yourself. To do this, you should use formulas based on SNiP 2.01.07-85 “Loads and impacts” and others regulatory documents. This option is the most difficult, but also the most reliable.

Complete independent calculation of loads is very labor-intensive. I will describe the main stages.

First we need to determine the load on the roof:

Weight load calculation- multiply the area of the slopes by the specific gravity of the roofing material. This value consists of the mass of the sheathing, waterproofing, insulation and roofing material, and on average ranges from 40 to 50 kg/m2.

Snow load calculation- regulatory snow load for your region, multiply by a coefficient depending on the angle of the slope. If the slopes are located at an angle of 60°, then we accept this coefficient equal to zero, if 30° - unity. Intermediate values are calculated using the formula µ = 0.033·(60 - α), where α is the slope angle.

The standard value of snow load is expressed in kg/m 3 and depends on the region. On the territory of the Russian Federation, the minimum value is 80 kg/m3, the maximum is 560 kg/m3.

Wind load calculation- we multiply the standard wind pressure in the region by the correction factor for the height of the building and by the aerodynamic coefficient (for strength it is advisable to take the minimum value - 0.8). The standard wind pressure ranges from 17 to 85 kg/m2, and the height coefficient is determined from the table below.

Height, m	Open area	Area with obstacles up to 10 m	Area with obstacles up to 20 m (urban development
Up to 5	0,75	0,5	0,4
5-10	1	0,65	0,4
10-20	1,25	0,85	0,53

We sum the obtained values to obtain the final value of the roof load.

To determine the parameters of the rafters used, we use two formulas. First we calculate the distributed load.

Qr=A·Q, Where:

Qr
A- rafter pitch, m;
Q- total load on square meter roofs, kg/m².

Then we determine the height of the section of the rafter beam. To do this, we select the optimal (as it seems to us) section width and substitute this value into the formula.

H =K·Lmax·sqrt(Qr/(B·Rben)), Where:

H- rafter section height, cm;
TO- slope coefficient. If the slope angle is less than 30°, we take it equal to 8.6, if more - 9.5;
Lmax - maximum length rafter working area, m;
Qr- load on the rafter leg, kg/m.;
B- cross-sectional width of the rafter leg, cm;
Rizg- bending resistance of wood, kg/cm² (for pine of the first grade we take it equal to 140, for the second grade - 130);
sqrt- Square root.

Calculation example:

Let's determine the parameters of the rafters for a roof with slopes of 36 degrees, with a rafter pitch of 0.28 and a length of the working part of 2.8 m. The frame is made of first-grade pine boards 5 cm wide, the total load on the roof (weight + snow + wind) is 300 kg/ m 2.

Qr=0.8·300=240 kg/m.
H= 9.5·2.8·sqrt(240/5·140) = 15.4 cm.

Since, according to calculations, we got a board larger than 150 mm, it is advisable to take thicker products. I would take parts with a cross section of 50x175 mm with guaranteed strength.

Yes, the calculation is quite complicated (and I gave an abbreviated version!). But by using it, you can check the dimensions of the supporting structures proposed to you and make sure (or not) of their reliability.

Equipment for work

Materials used

Based on the calculations, you can purchase parts for the frame, sheathing, insulation, waterproofing and roofing material. The indicative list of materials includes the following items:

Illustration	Material
	Details for the rafter system. Roof rafters are made of timber or boards with a thickness of 40 mm, a height of 100–250 mm and a length of up to 6 m. You can also include beams or logs for support posts (when installing a layered system), a Mauerlat and a ridge beam. The ideal material for the manufacture of all these elements is well-dried pine wood of the first or second grade.
	Sheathing details. Lathing and counter-lattice are a fairly light frame that is attached over the rafter system for installation of roofing material. It is made either from slats with a section of 30x30 or 20x40 mm, or from boards from 25 mm, or from plywood with a minimum of 15 mm. The choice of sheathing type is determined by the roofing material.
	Roof thermal insulation. Mounted on the underside of the slopes. Most often, slabs with a thickness of 75–150 mm based on mineral wool are used for roof insulation.
	Waterproofing. It is best to purchase special roofing membranes (Ruvitex, Tyvek and analogues) that combine waterproofness with vapor permeability. Thanks to this, condensation will not collect in the under-roof space, and the insulation will not suffer from moisture.
	Roofing material. The choice here is huge. Gable roofs can be covered with: · metal tiles; · corrugated sheets; · flexible tiles; · ceramic tiles; · slate (standard and polymer), etc.
	Additional roofing elements. This includes parts that are used for installation in areas experiencing high operational loads. Most often, a set of additional elements includes: ridge strips; cornice strips; end strips; strips connecting to vertical surfaces; soffits, etc.
	Drainage system. Can be made of galvanized steel, metal with polymer coating or made of plastic. It is represented by a fastening system, gutters around the perimeter of the roof, inlet funnels and drainpipes.

In addition to the basic elements listed, we will need:

Rolled waterproofing materials (roofing felt) for laying at the point of contact of the rafter system with the walls of the building.
Fasteners (nails, screws, anchors, studs with fixing nuts, etc.).
Metal plates and brackets to strengthen the attachment points of wooden elements.
Adhesive tapes for joining rolled materials.
Impregnations for wood are antiseptic and reduce flammability.

Set of tools

To construct the rafter system, install the sheathing and lay the roofing, you will need the following tools:

Wood saw (preferably several, and different ones - a miter saw for basic trimming, a circular saw for smaller work, a reciprocating saw or a hacksaw for fitting).
Carpenter's axes (yes, it is still more convenient to cut out grooves with a good ax).
A hammer drill with drills for the material from which the load-bearing walls are made.
Drill with a set of drills.

Screwdrivers (one per technician).
Levels (laser for setting the frame, several water levels for leveling additional elements).
Roulettes.
Plumb lines.
Hand tools - hammers, pliers, chisels, etc.
Brushes for applying moisture-proof impregnations, coating waterproofing etc.

Since you will have to work at heights, you cannot do without several ladders, scaffolding and scaffolding for building materials.

You also need to take care of personal protective equipment, including overalls, helmets and harnesses.

Roof installation

Stage 1. Installation of the Mauerlat

We begin to install the gable roof frame by installing the support beam - the Mauerlat. To make it, we take 100x100 or 150x150 mm timber from dry pine wood.

We mount the Mauerlat according to this scheme:

Illustration	Sequencing
	Preparing the end of the wall. U wooden house The upper crown acts as a Mauerlat. For a brick or concrete building, it is advisable to pour a reinforced belt under the Mauerlat. We reinforce walls made of foam or aerated concrete with metal mortgages, after which we level the surface with mortar.
	Waterproofing. We lay a waterproofing layer at the junction of concrete/brick and mauerlat roll material- roofing felt or its analogues. This will protect the wood from destruction under the influence of capillary moisture.
	Laying the Mauerlat. We place the support beam on the end of the wall and carefully align it so that it lies without protrusions or distortions.
	Drilling for fasteners. We drill holes in the Mauerlat and supporting wall for installing anchors. We carry out drilling in two steps: first we go through a wooden beam with a drill, and then we make a nest in the wall fence with a hammer drill and drill. When working with structures made of porous concrete, we use special drills, since impact drilling can lead to the formation of cracks.
	Installation of fasteners. We insert anchors with a thickness of 10 m into the holes and deepen them with hammer blows.
	Final fixation. Screw in the fastening nuts of the anchors. At the same time, the anchor sleeve expands, securely fixing it to the base.

This is not the only way to fix the Mauerlat on the wall fence. Sometimes steel studs with a thickness of 12 mm or more are embedded in brick or block masonry, and the timber with drilled holes is put on them and secured with nuts and wide washers. This method is more reliable, but also more labor-intensive - the studs need to be laid in advance, even at the stage of constructing the supporting structure.

Stage 2. Installation of racks, purlins and rafters

Instructions for installing the roof frame - rafters and additional elements - depend on the design of the rafter itself. Here I will give a description of the installation of a layered roof:

Illustration	Sequencing
	Laying the bed. We lay a beam on the central load-bearing wall, which will serve as a support for the racks and purlins. We fix the beam to the base in the same way as the Mauerlat - with mandatory reinforcement, waterproofing and fixation with anchors.
	Installation of the purlin. We connect the upper parts of the gables with a long longitudinal beam - a purlin. If the gables are a continuation of the main walls, then the girder is based on vertical racks, installed close to the gable parts.
	Installation of racks. With a pitch equal to the selected pitch of the rafters, we install vertical posts connecting the purlin and the beam. We align the racks according to the level, and be sure to fix them at the top and bottom with steel corners and secure them with self-tapping screws.
	Preparing rafter legs. We cut the boards intended for making rafters to size and, if necessary, level them with a plane. We dilute concentrated wood impregnation (antiseptic + fire retardant) and treat future rafters from all sides. Dry the treated wood thoroughly.
	Marking the rafters. We attach the rafter legs to the frame (the lower part rests on the mauerlat, the upper part on the purlin) and fix it with clamps to the temporarily stuffed bars. Using a square, mark where you need to make a cutout for attaching the rafters.
	Laying rafters. We make cuts according to the markings using a hacksaw or reciprocating saw. We put the rafter legs in place, carefully aligning them. If necessary, trim the edges of the cutout with a carpenter's axe.
	Docking at the top. We cut the upper ends of the rafter legs so that they meet with a gap of no more than 1–2 mm. We secure the rafters to the purlin with metal corners. We connect both parts with a steel plate with a thickness of at least 1.5 mm.
	Lower part fastening. We fix the base of the rafter leg on the mauerlat, drilling a diagonal hole and screwing a long self-tapping screw into it. When installing rafters from wide board with a small thickness, you can also use metal corners made of steel with a thickness of 2 mm.
	Installation of the bottom puffs. At the bottom of each truss we install long cross boards, each of which must connect the left rafter, the post and the right rafter. We align the boards by level, fixing each with at least two screws. To strengthen the fastening, you can tighten the parts with bolts. We cut the protruding edges of the puffs diagonally flush with the rafters,
	Installation of the top puffs. Exactly in the same sequence we fasten the upper tightenings. They must be located exactly under the purlin.
	Trimming the rafters. We trim the edges of the rafters, forming vertical and horizontal surfaces for installing the eaves strips. It is very important to trim all the rafters of the slope at the same level, so we carefully take all measurements before starting the operation.
	End decoration. We put a front board on the vertical sections of the rafters, carefully leveling it. At the bottom of each rafter we cut out a small sample, after which we lay a narrow board with a thickness of 20 mm in it and fix it with self-tapping screws. This board will serve as the basis for installing droppers.

As I noted above, this is not the only design scheme. Other options for rafter systems are possible, but if you do not have experience, you should start mastering the technique with simple and proven algorithms.

Stage 3. Installation of sheathing, waterproofing and roofing work

So, the supporting structure of the gable roof is ready. Now we need to turn the frame into a full-fledged roof. This work is no longer as large-scale, but still labor-intensive.

Main stages:

Installation of waterproofing. We roll out rolls of waterproofing membrane horizontally on the rafters, fixing it directly to the rafter legs using galvanized staples. We lay the waterproofing with an overlap (from 100 to 300 mm, the greater the slope angle, the less overlap). Be sure to glue the joints of the panels.

Where ventilation and chimney pipes pass through the roof, as well as along the ridge, we install additional waterproofing.

Installation of sheathing/counter-lattice. Additionally, we fix the waterproofing material by stuffing along the rafters wooden blocks with a cross section of at least 30x30 mm. On top of these bars we install a sheathing under the roofing material - slats, boards or plywood sheets. To fasten the sheathing we use wood screws.

Thermal and vapor insulation of the roof. On the inside, between the rafters we lay thermal insulation mats, which minimize energy losses through the slopes. If the price of mineral wool turns out to be prohibitive, you can also use polystyrene foam - but in this case it is advisable to take care of additional ventilation. We cover the insulation with a vapor barrier membrane, and then fix it with cross bars or sheathing made of plywood or chipboard.

Installation of the selected roofing material. We begin work from the perimeter, installing cornice and end strips. Then we install the roofing material on the slopes, taking care not to damage the waterproofing during installation. We fix the roofing sheets to the sheathing.

Installation of additional elements. We install additional roofing elements - a ridge strip that covers the junction of the slopes in the upper part, strips connecting to chimneys and ventilation, etc.

Installation of a drainage system. We fix fasteners for gutters to the front board or to the end parts of the rafters. We install gutters along the slopes with a slope towards the receiving funnels. We place funnels at the edges, from which we lower drainpipes.

Conclusion

A gable roof is just the option with which you can start mastering roofing skills. After studying my instructions and the video in this article, you will receive the minimum knowledge necessary for work, and then it’s a matter of practice. If you have any questions, ask them in the comments.

IN individual construction gable roofs are much more common than other options. The explanation lies not only in practicality for our latitudes, but also in the design of the rafter system.

For arrangement gable roof rafters are laid along the simplest scheme, without requiring either serious calculations or complex installation works

In this case, material consumption will be minimal, and strength design - maximum.

Rafter system options

Despite all simplicity structures, rafter systems can be created under a gable roof several types.

Here the choice will depend on how you plan to use attic space and what are the design features of the house itself.

So, roof slopes can be made equal or various lengths. The latter option gives the cottage’s exterior originality and allows it to better adapt to the wind rose and climatic features.

By type of structure rafter systems, gable roofs are divided into the following main ones groups:

Layered rafters

A similar rafter system is used in houses that have in their middle part longitudinal main wall. In this case, it is transmitted from the ridge through the vertical elements to central load-bearing wall. The ridge itself takes on the weight of the rafter legs, delivering the entire system without the need for cross members.

Hanging rafters

This option is the most practical with a house width from 6 to 14 m. Small permissible width home for such a system is explained by significant load on the walls. The rafters rest with all their weight on the walls, the limit strength which is not unlimited.

To reduce the load on the walls, hanging rafters are introduced into the structure additional reinforcement elements: struts, tightening, headstock, crossbars, etc. Strengthening nodes can be located arbitrary Therefore, they are often given a double functional load. For example: Tightenings installed at the lowest point of the rafter system also successfully cope with the role of beams ceiling ceilings

Main design elements

Individual elements and nodes rafter frames can be made of both wood and reinforced concrete. In individual construction, the first option is more common.

The rafter system consists of the following structural elements:

which is a high-strength beam that is laid on load-bearing walls and takes on the weight of the rafters;
rafter legs. These are inclined beams, which are the basis for connecting all elements and determine the shape of the roof;

horse, formed by the junction of roof slopes;
fillies. These are boards or pieces of timber that are used to extend rafter legs to create an overhang if the rafters are not long enough;

eaves, performing the function of protecting walls from snow and water coming off the slopes;
racks, removing part of the load from the rafter legs. Installed vertically under purlins;
struts in the form of inclined beams, the upper part supporting the purlins, and the lower resting against the bench or mauerlat;

puff, connecting the rafter legs horizontally, preventing them from diverging;

lying down - longitudinal beam laid in the same plane with the Mauerlat under the ridge;
sheathing, stuffed across the rafter legs. Thanks to the lathing, the weight of the roofing material is distributed more evenly.

The elements of the rafter system are connected to each other either with nails or bolts through drilled holes. Joints converging at an angle can be reinforced with overhead metal plates or boards.

Important! When preparing material for creating a wooden rafter system, it is necessary to pay attention not only to the quality of drying and absence of damage, but also to the presence of knots. If there are any, their dimensions should not exceed a third of the thickness of the board or timber.

Installation steps

Installation sequence rafter system gable roof will be as follows:

Fastening the Mauerlat

For the device, either logs trimmed at the top and bottom are used, or

Minimum material cross-section – 100 x 150 mm.

Before the final styling Mauerlat will require preparation:

on top part load-bearing wall, two layers of dense waterproofing material;
the timber is impregnated with solution antiseptic For
individual parts of the Mauerlat are laid out along the walls to determine their lengths. Checked along the way density landing in a prepared place.

fasten Mauerlat can be any in an accessible way, however more reliable and the easiest way to use anchor fasteners:

anchor bolts strictly vertically fixed on load-bearing walls;
in the bars of the Mauerlat are drilled out holes;
the Mauerlat is mounted on the bolts and finally fixed.

Since the timber has a significant cross-section, its laying over long fastening bolts are often problematic. To simplify the task, before laying the timber on the wall, stacks of thin boards are placed flush with the cut of the bolts. As these boards are removed from under the timber, it will be pushed onto the bolts evenly along its entire length.

Commit the Mauerlat beam can be either screwed on with nuts and washers, or welding piece of reinforcement.

Installation of rafters

Sequence of actions during installation rafters will be like this:

two beams of the first pair are lifted onto the working platform rafter legs, the length of which must be calculated in advance;
in places connections rafter legs with a mauerlat are marked and cut out on them fastening cut;
at the upper junction(under the ridge) both rafter legs are trimmed Thus, to the point overlap they could tightly connect;
the joint of the rafter legs is fixed with nails or bolts. Next, the work is repeated for each pair of rafter legs. Optimal step rafters at the same time - 70 cm;
timber is installed and fixed puffs;
installed under the upper joint of the rafter legs vertical beam (grandmother);
a horizontal one is placed on top of the rafters sheathing.

Ridge installation

To give rigidity rafter system with a central support must be installed ridge run.

It is advisable that there be under it carrier wall. In its absence, planks are laid on parallel load-bearing walls, and beams are installed on them for additional strengthening the support.

For the manufacture of ridge girders, profiled timber with a cross section of 100 x 150 mm or board with a cross section of 50 x 150 mm or more.

And they are calculated taking into account the wind and snow load on the roof of the house.

Check carefully using a level horizontality ridge run and its parallelism cut the wall.

Attention! Due to incorrect installation of the ridge girder, problems may arise with the installation of roofing materials, leaks will appear, which will lead to emergency roof repairs.

Ridge part rafter system must have maximum possible strength. A certain degree of rigidity of the entire structure is provided runs. However, at the highest point it will be necessary to create an additional stiffening rib.

For this sheathing in the upper part of the roof should be packed tightly. Optimal width reinforced part of the sheathing under the ridge - 40–60 cm. The durable ridge part will not only provide high level security roofing works, but also will make it easier even laying of the roof covering.

From thoughtfulness and thoroughness the execution of the rafter system largely depends efficiency the entire roof. But building a neat, inexpensive and beautiful roof is quite accessible to anyone home handyman. You just need to study diagram installation of rafters, purchase material and do not deviate from time-tested recommendations.

For more information on the construction of a gable roof truss system, see video:

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

Gable roof frame in effect design features ideally combines simplicity of design and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof practical and rational decision for private and commercial housing construction.

In this article, we will look at how to make a rafter system for a gable roof with your own hands. For effective perception of the material, it is presented in the form of step-by-step instructions from A to Z, from selection and calculations, to installation of the Mauerlat and sheathing under the roof. Each stage is accompanied by tables, diagrams, drawings, drawings and photos.

The popularity of the house roof is due to a number of advantages:

design variability;
simplicity in calculations;
naturalness of water flow;
integrity of the structure reduces the likelihood of leaks;
efficiency;
preservation usable area attic or the possibility of arranging an attic;
high maintainability;
strength and wear resistance.

Types of gable roof

The installation of a gable roof truss system depends, first of all, on its design.

There are several options for gable roofs (types, types):

The most common roof installation option due to its simplicity and reliability. Thanks to symmetry, a uniform distribution of loads on the load-bearing walls and mauerlat is achieved. The type and thickness of the insulation does not affect the choice of material.

The cross-section of the beam makes it possible to provide a reserve of bearing capacity. There is no possibility of rafters bending. Supports and struts can be placed almost anywhere.

An obvious drawback is the impossibility of arranging a full attic floor. Because of sharp corners“dead” zones appear that are unsuitable for use.

The arrangement of one angle of more than 45° leads to a reduction in the amount of unused area. There is an opportunity to do living rooms under the roof. At the same time, the requirements for calculations increase, because the load on the walls and foundation will be distributed unevenly.

This roof design allows you to equip a full second floor under the roof.

Naturally, a simple gable rafter roof differs from a broken roof, not only visually. The main difficulty lies in the complexity of the calculations.

Design of a gable roof truss system

Building a roof of any complexity with your own hands requires knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

Mauerlat. Designed to distribute the load from the rafter system onto the load-bearing walls of the building. To arrange the Mauerlat, a timber made of durable wood is selected. Preferably larch, pine, oak. The cross-section of the timber depends on its type - solid or glued, as well as on the expected age of the structure. The most popular sizes are 100x100, 150x150 mm.
Advice. For a metal rafter system, the Mauerlat must also be metal. For example, a channel or an I-profile.

Rafter leg. The main element of the system. To make rafter legs, a strong beam or log is used. The legs connected at the top form a truss.

The silhouette of the roof truss defines appearance buildings. Examples of farms in the photo.

The parameters of the rafters are important. About them we'll talk a little lower.

Puff- connects the rafter legs and gives them rigidity.

Run:

Ridge run, is mounted at the junction of one rafter to another. In the future, the roof ridge will be installed on it.

Side purlins, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

Rafter stand- vertically located beam. It also takes on part of the load from the weight of the roof. In a simple gable roof it is usually located in the center. With a significant span width - in the center and on the sides. In an asymmetrical gable roof, the installation location depends on the length of the rafters. With a broken roof and arrangement of one room per attic attic- the racks are located on the sides, leaving free space for movement. If there are supposed to be two rooms, the racks are located in the center and on the sides.

The location of the rack depending on the length of the roof is shown in the figure.

Strut. Serves as a support for the stand.

Advice. Installing the brace at an angle of 45° significantly reduces the risk of deformation from wind and snow loads.

In regions with significant wind and snow loads, not only longitudinal struts are installed (located in the same plane as the rafter pair), but also diagonal ones.

Sill. Its purpose is to serve as a support for the rack and a place for attaching the strut.

Lathing. Designed for movement during construction work and fixation of roofing material. Installed perpendicular to the rafter legs.

Advice. An important purpose of the sheathing is to redistribute the load from the roofing material to the rafter system.

Having a drawing and diagram indicating the location of all the listed structural elements will help in the work.

Advice. Be sure to add information about the passage of the ventilation shaft and chimney to the gable roof rafter system diagram.

The technology of their installation is determined by the type of roof.

Selection of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage or wormholes. The presence of knots for beams, mauerlat and rafters is not allowed.

For sheathing boards, there should be a minimum of knots, and they should not fall out. The wood must be durable and treated with the necessary preparations that will increase its properties.

Advice. The length of the knot should not exceed 1/3 of the thickness of the timber.

Calculation of the rafter system of a gable roof

Calculation of material parameters important stage, so we present the calculation algorithm step by step.

It is important to know: the entire rafter system consists of many triangles, as the most rigid element. In turn, if the stingrays have different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and amount of materials for each. After calculations, summarize the data.

1. Calculation of the load on the rafter system

The load on the rafters can be of three types:

Constant loads. Their action will always be felt by the rafter system. Such loads include the weight of the roof, sheathing, insulation, films, additional roofing elements, finishing materials for. The weight of the roof is the sum of the weight of all its constituent elements; such a load is easier to take into account. On average, the constant load on the rafters is 40-45 kg/sq.m.

Advice. To make a safety margin for the rafter system, it is better to add 10% to the calculation.

For reference: The weight of some roofing materials per 1 sq.m. presented in the table

Advice. It is desirable that the weight of roofing material per 1 sq.m. roof area did not exceed 50 kg.

Variable loads. They act at different times and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

In essence, the roof slope is like a sail and, if you take into account the wind load, the entire roof structure can be destroyed.

The calculation is carried out using the formula: wind load is equal to the regional indicator multiplied by the correction factor. These indicators are contained in SNiP “Loads and Impacts” and are determined not only by the region, but also by the location of the house. For example, on a private house surrounded multi-storey buildings, there is less load. Standing separately Vacation home or the cottage experiences increased wind loads.

2. Calculation of snow load on the roof

The roof calculation for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow that falls on 1 square meter. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg/sq.m.

Coefficients showing the dependence on the slope angle are shown in the photo.

Nuance. When the slope angle is over 60 ° the snow load does not affect the calculation. Because the snow will quickly slide down and will not affect the strength of the beam.

Special loads. Accounting for such loads is carried out in places with high seismic activity, tornadoes, and storm winds. For our latitudes, it is enough to make a safety margin.

Nuance. The simultaneous action of many factors causes a synergy effect. This is worth considering (see photo).

Assessment of the condition and load-bearing capacity of walls and foundations

It should be borne in mind that the roof has significant weight, which can cause damage to the rest of the building.

Determining the roof configuration:

simple symmetrical;
simple asymmetrical;
broken line

How more complex form roof, the greater the number of trusses and sub-rafter elements needed to create the necessary safety margin.

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward their own demands.

soft roof - 5-20°;
metal tiles, slate, corrugated sheets, ondulin - 20-45°.

It should be noted that increasing the angle increases the area of space under the roof, but also the amount of material. What affects the total cost of work.

Nuance. Minimum angle The slope of the gable roof should be at least 5°.

5. Calculation of rafter pitch

The pitch of the gable roof rafters for residential buildings can be from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the slope by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per slope. For the second, the number must be multiplied by 2.

The length of the rafters for the attic roof is calculated using the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a living space under the roof, the convenience of being in the attic, and the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" represents the hypotenuse of the triangle.

Advice. To the obtained value you need to add 60-70 cm for cutting and moving the rafter leg beyond the wall.

It is worth noting that the maximum length of the timber is 6 m.p. Therefore, if necessary, the timber for the rafters can be spliced (extension, joining, joining).

The method of splicing rafters along the length is shown in the photo.

The width of the roof rafters depends on the distance between opposite load-bearing walls.

7. Calculation of the rafter cross-section

The cross-section of the rafters of a gable roof depends on several factors:

loads, we have already written about it;

type of material used. For example, a log can withstand one load, timber - another, laminated timber - a third;

rafter leg lengths;

the type of wood used in construction;

distances between rafters (rafter pitch).

You can determine the cross-section of the beam for the rafters, knowing the distance between the rafters and the length of the rafters using the data below.

Rafter cross-section - table

Advice. The larger the installation pitch of the rafters, the greater the load on one rafter pair. This means that the cross-section of the rafters needs to be increased.

Dimensions of lumber (timbers and boards) for a gable rafter system:

thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

the thickness of the rafter leg and tie is 10x15 or 10x20 cm. Sometimes a beam of 5x15 or 5x20 cm is used;

run and strut - 5x15 or 5x20. Depending on the width of the foot;

stand - 10x10 or 10x15;

bench - 5x10 or 5x15 (depending on the width of the rack);

thickness (section) of the roof sheathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof rafter system

For the roof structure under consideration, there are 2 options: layered and hanging rafters.

Let's consider each type in detail in order to make an informed choice.

Hanging rafters

They are used for roof widths of no more than 6 lm. Installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and the ridge girder. The design of hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a tie installed between the legs reduce its impact. The tie in the rafter system can be wooden or metal. Often the puffs are placed at the bottom, then they play a role load-bearing beams. It is important to ensure that the tie is securely attached to the rafter leg. Because a bursting force is also transmitted to it.

Advice.
The higher the tightening is located, the greater strength it should have.
If the tightening is not installed, the load-bearing walls may simply “move apart” from the pressure created by the rafter system.

Layered rafters

They are used for arranging roofs of any size. The design of layered rafters provides for the presence of a beam and a stand. The bench lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs are, as it were, inclined towards each other and supported by a stand. The rafter legs of the layered system work only in bending. And the ease of installation also tips the scales in their favor. The only drawback is the presence of a stand.

Combined

Due to the fact that modern roofs are distinguished by a wide variety of shapes and complexity of configurations, a combined type of rafter system is used.

After choosing the type of rafter system, you can accurately calculate the amount of materials. Write down the calculation results. At the same time, professionals recommend drawing up drawings for each roof element.

Installation of a gable roof rafter system

After the gable roof rafters have been calculated, installation can begin. We will divide the process into stages and give a description of each of them. It will turn out to be unique step-by-step instruction, containing additional information for each stage.

1. Attaching the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log houses, the role of the mauerlat is played by the upper crown. In buildings built from porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

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Since the length of the Mauerlat exceeds standard sizes lumber, it has to be spliced.

The connection of the Mauerlat to each other is done as shown in the figure.

How to connect the Mauerlat?

The beams are cut only at an angle of 90°. Connections are made using bolts. Nails, wire, and wooden dowels are not used.

How to attach the Mauerlat?

The Mauerlat is installed at the top of the wall. The installation technology provides several ways to attach the Mauerlat:

strictly in the center of the load-bearing wall;
with a shift to one side.

Advice.
The Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the timber for the Mauerlat from damage, it is laid on a layer of waterproofing material, which most often is ordinary roofing felt.

The reliability of the Mauerlat fastening is an important aspect of construction. This is due to the fact that the roof slope is like a sail. That is, it experiences strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Anchor bolts. Ideal for monolithic structures.

Wooden dowels. Used for log houses and beams. But, they are always used with additional fasteners.

Staples.

Stud or fittings. It is used if the cottage is built from porous materials (aerated concrete, foam concrete).

Sliding mount (hinge). Tying in this way allows for the displacement of the rafter legs when the house shrinks.

Annealed wire (knitting, steel). Used as additional fastening In most cases.

2. Manufacturing of trusses or pairs

Installation is carried out in two ways:

installation of beams directly on the roof. It is not used often, since it is problematic to carry out all the work, measurements, and trimming at height. But it allows you to completely do the installation yourself;

assembly on the ground. That is, individual elements (triangles or pairs) for the rafter system can be assembled below and then raised to the roof. The advantage of such a system is faster performance of high-altitude work. The disadvantage is that the weight of the assembled truss structure can be significant. To lift it you will need special equipment.

Advice. Before assembling the rafter legs, you need to apply markings. It is very convenient to use templates for these purposes. The rafter pairs assembled according to the template will be absolutely identical. To make a template, you need to take two boards, the length of each of which is equal to the length of one rafter, and connect them together.

3. Installation of rafter legs

The assembled pairs rise to the top and are installed on the Mauerlat. To do this, you need to make a gash at the bottom of the rafter legs.

Advice. Since the slots on the Mauerlat will weaken it, you can only make cuts on the rafter leg. To ensure that the cut is uniform and fits tightly to the base, you need to use a template. It is cut out of plywood.

Methods of fastening the rafter leg are shown in the figure.

You need to start installing rafter pairs from opposite ends of the roof.

Advice. To correctly install the rafter legs, it is better to use temporary struts and spacers.

A string is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. It will also indicate the level of the ridge.

If the rafter system is mounted directly on the roof of the house, then after installing the two outer rafter legs, the ridge support is installed. Next, the halves of the rafter pair are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered fastening pattern, which will allow the increasing load to be distributed more evenly on the walls and foundation. This order involves installing one rafter in a checkerboard pattern. After part of the rafter legs is installed, the missing parts of the pair are mounted. Others insist that it is necessary to mount each pair in a sequential manner. Depending on the size of the structure and the configuration of the truss, the rafter legs are reinforced with supports and racks.

Nuance. Additional structural elements are connected using cutting. It is preferable to fix them with construction staples.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Advice. The method by which the mauerlat is lengthened (cut at 90°) cannot be used in this case. This will weaken the rafter.

4. Installing the ridge of a gable roof

The roof ridge unit is made by connecting the rafter legs at the top.

Roof ridge structure:

Method without using a support beam (see figure).

Method using rafter beams. Timber is needed for large roofs. In the future, it can become a support for the rack.

Method of laying on timber.

More modern variety manufacturing ridge knot can be considered the method shown in the photo.

Cutting method.

After the rafter system is installed, we perform major fastening of all structural elements.

5. Installation of roof sheathing

The sheathing is installed in any case, and is designed for more convenient movement along the roof during work, as well as for fastening roofing material.

The sheathing pitch depends on the type of roofing material, for example:

for metal tiles - 350 mm (the distance between the two lower boards of the sheathing should be 300 mm).
for corrugated sheets and slate - 440 mm.
We lay a continuous sheathing under the soft roof.

Rafter system of a gable roof with an attic - video:

Conclusion

As you can see, despite its apparent simplicity, the installation of a gable roof rafter system contains many pitfalls. But, based on the recommendations given, you can build without any problems reliable design with your own hands.

When constructing one-story houses, a roof with two slopes is very popular. This is due to the speed of construction of the structure. In this parameter, only a single-pitched roof can compete with a gable roof. The design of the gable rafter roof is not too complicated. And you will successfully master this work on your own.

Design of a gable roof truss system

A gable roof consists of two inclined surfaces that have a rectangular shape. Thanks to this, precipitation, which is represented by rain and melt water, drains from the roof naturally. The gable roof has a rather complex structure. It consists of the following structural units: mauerlat, rafter system, fillies, ridge, roof overhang, bed, struts, tie-downs, sheathing and racks:

Mauerlat. This element performs the functions of transferring and distributing the load created by the rafter system onto the load-bearing walls of the house. To make the Mauerlat, timber is used, which has a square cross-section - from 100 by 100 to 150 by 150 mm. It is better to use coniferous wood. The timber is placed around the perimeter of the building and secured to the external walls. For fastening, special rods or anchors are used.
Rafter leg. Rafters form the main frame of any roof. In the case of a gable roof, they form a triangle. The rafters are responsible for the uniform transfer of loads to the Mauerlat. First of all, those that arise from precipitation, wind and the weight of the roof itself. For the manufacture of rafters, boards are used that have a cross-section of 100 by 150 or 50 by 150 mm. Choose a rafter pitch of about 60-120 cm, depending on the type of roofing material. When using heavy coverings, place rafter legs more often.
Horse. This element connects the two slopes at the top of the roof. The ridge is formed after connecting all the rafter legs.
Fillies. They act as a continuation of the rafters and form the overhang of the gable roof. It is customary to install fillies if the rafter legs are very short and do not allow the formation of an overhang. To make this structural unit, take a board that has a smaller cross-section than the rafter. The use of fillies facilitates the construction of the rafter system, as it allows the use of short rafters.
Eaves. This part of the design of the gable roof truss system is responsible for draining water from the walls during rain and at the same time preventing them from getting wet and quickly collapsing. The overhang from the wall, as a rule, protrudes 400 mm.
Sill. It is located on the inner wall and serves to uniform distribution loads from roof pillars. To make the bed, a timber is used, which has a cross-section of 150 by 150 or 100 by 100 mm.
Racks. These vertical elements are responsible for transferring the load from the ridge to the interior walls. To create this element, prepare a beam that has a square section of 150 by 150 or 100 by 100 mm.
Struts. They are needed to transfer loads from the rafters to the load-bearing walls. The struts and tightenings form robust construction which is called a farm. Similar device designed to withstand loads over large spans.
Puff. This structural unit, together with the rafters, forms a triangle. It does not allow the rafters to move in different directions.
Lathing. This structure consists of boards and bars. They are attached perpendicular to the rafters. Lathing is necessary to evenly distribute the weight of the roof covering and the loads created by the rafters. weather events. In addition, sheathing is required to fasten the rafters together. When arranging a soft roof, moisture-resistant plywood should be used to create sheathing rather than boards and bars.

Types of gable roof rafter system

There are gable rafter systems with hanging and layered rafters. Ideally, the design contains a combination of them. It is customary to install hanging rafters if the external walls are located at a distance of less than 10 m. Also, between them there should no longer be walls that divide the space of the residential building. The design with hanging rafters creates a bursting force transmitted to the walls. It can be reduced if you make a tie made of wood or metal and place it at the base of the rafters.

The rafters and the tie form a rigid geometric figure - a triangle. It is not capable of deforming under loads that appear in any direction. The tightening will be stronger and more powerful if it is positioned higher. The tie beams are the floor beams. Thanks to their use, the hanging rafter system of a gable roof serves as the basis for arranging the attic floor.

In their design, layered rafters have a support beam, which is placed in the middle. It is responsible for transferring the weight of the entire roof to the intermediate columnar support or middle wall located between external walls. It is recommended to install layered rafters if the external walls are located at a distance of more than 10 m. If there are columns instead interior walls, you can alternate between layered and hanging rafters.

DIY gable rafter system

The roof must be strong to withstand various loads - precipitation, gusts of wind, the weight of a person and the roofing itself, but at the same time light, so as not to put much pressure on the walls of the house. A properly constructed gable rafter roof evenly distributes the load across all load-bearing walls.

Calculation of a gable roof

The choice of slope for a gable roof will depend on the material you have chosen for laying on the roof and architectural requirements:

When erecting a gable roof, remember that it must slope at an angle of more than 5 degrees. It happens that the roof slope reaches 90°.
For areas with heavy rainfall, and when the roofing does not fit tightly, steep slopes are made. In this situation, the angle should be 35-40° so that precipitation does not linger on the roof. But such an angle does not allow building a living space in the attic. The solution will be a broken roof structure. It will have a flat upper part, and a sharp slope at the lower part.
In regions with strong gusts of wind, flat roofs are installed. If constant winds prevail in the area, then make a slope of 15-20° for high-quality protection of the roofing.
It is best to choose the middle option. Make sure the gable roof is not too steep. But the slope should also not be very gentle.
When choosing a large roof angle, its windage increases, and, accordingly, the price of the gable roof rafter system and sheathing increases. After all, such a slope entails an increase in the roof area and, accordingly, the amount required material- construction and roofing.

When purchasing materials for constructing a gable roof, it is useful to calculate its area:

Find the area of one slope of the structure, and then double the result.
Ideally, the slope is an inclined rectangle that is placed along a long load-bearing wall. To determine the area of the slope, multiply its length by its width.
The length of the slope is equal to the length of the wall. In addition, the length of the roof overhang above the gable is added to the length. Remember that there are tabs on both sides.
The width of the slope is the length of the rafter leg. The length of the roof overhang above the load-bearing wall is added to it.

In order to correctly design the structure, it is recommended to carry out an accurate calculation of the rafter system of a gable roof, including determining the loads and characteristics of the rafters:

When erecting a roof for a standard building that has one floor, the design load on the roof will consist of two values. The first of them is the weight of the roof, the second is the load from external factors: precipitation and wind.
Calculate the weight of the roof by adding up the weight of each layer of the “pie” - thermal insulation, vapor barrier and waterproofing materials, rafter system, sheathing and roofing material itself. Calculate the weight per 1 m2.
Increase results by 10%. You can also take into account the correction factor. In our case K=1.1.
If you plan to change the roof structure over time and increase its angle of inclination, then factor in a safety margin into the calculation. Immediately take higher loads than those you received at the time of calculation. It is recommended to start from a value of 50 kg per 1 m2.
When calculating the load exerted atmospheric phenomena, take into account the climatic features of the area where the building is located. When making this calculation, take into account the slope of the slope. If the gable roof forms an angle of 25 degrees, then assume a snow load of 1.
If the roof is equipped with a greater slope - up to 60 degrees, the correction factor reaches 1.25. Snow loads for angles greater than 60 degrees are not taken into account.
The rafters transfer the entire load from the created structure to the load-bearing walls. Therefore, their parameters must be taken accordingly. Select the cross-section and leg length of the rafters, depending on the current load on the roof and the angle of the slope. Increase the obtained values by 50% to ensure a high safety margin.

Mauerlat installation methods

The construction of any roof begins with the installation of the Mauerlat:

If logs or beams were used to build the walls, then top beam and will act as a mauerlat, as shown in the photo of the gable roof rafter system.
If you used brick to build the walls, then wall up metal rods into the masonry. They must have a thread cut for attaching the Mauerlat. Install rods every 1-1.5 m. Choose rods with a diameter of at least 10 mm. Lay waterproofing between the masonry and the mauerlat.
For walls made of ceramic or foam concrete blocks, pour concrete on top. Be sure to make the layer reinforced. It should have a height of approximately 200-300 mm. Be sure to attach metal rods that have threads to the reinforcement.
For the Mauerlat, use a beam that has a cross-section of 15 by 15 cm. It will act as a kind of foundation for the rafter system.
Place the Mauerlat on the top edge of the wall. Depending on its design, the Mauerlat can be laid along the outer and inner edges. Do not place it close to the very edge, otherwise the wind may blow it off.
It is recommended to place the Mauerlat on top of the waterproofing layer. To connect all parts into one, use bolts and metal plates.
To avoid sagging, make a lattice from racks, struts and crossbars. To do this, take boards measuring 25x150 mm. The angle between the strut and the rafter leg should be as straight as possible.
If you use a rafter leg that is too long, install another support. She should rest on the bed. Each element is associated with two neighboring ones. The result is a stable structure around the entire perimeter of the roof.

Fastening rafter legs

Most the best option gable roof rafter system - a combination of inclined and hanging rafters. This design allows you to create a reliable gable roof and reduce the cost of building materials. Consider the following recommendations when working:

Use only the highest quality wood as material. Beams that have cracks and knots should absolutely not be used.
The rafters have standard dimensions - 50x150x6000 mm. When beams are longer than 6 m, it is recommended to increase the width of the board so that the beams do not break under their own weight. Take boards 180 mm wide.
First make a template for the rafter leg. Attach the board to the floor beam and the end of the ridge beam. Having outlined two lines, saw off the board along them. The template is ready.
Cut the rafters according to this template. After this, make the top cut on them.
Take the resulting workpiece and bring it to the floor beam to mark the bottom cut in place.
Install all rafters. At the same time, remember that after installing one leg, you must immediately install the opposite one. This way you will quickly remove the lateral loads on the ridge beam.
If the slope is too long, then standard boards will not be enough to make a rafter leg. In this case, you can join two boards together. To do this, sew on them a piece of wood of a similar cross-section. It should have a length of 1.5 - 2 meters. According to the gable roof rafter system diagram, the joint should always be at the bottom. Install an additional stand under it.
Attach the rafter leg to the ridge beam using nails. To attach the rafters to the floor beam, use self-tapping screws. Metal mounting plates are also suitable. In addition, a few nails are added.
If you are building a structure entirely from hanging rafters, then skip the next stage. When erecting a structure with layered rafters, you need to think about the supports that are installed on the floor. To reduce the deflection of the rafters, correctly calculate the location of such supports.
If you are building a gable mansard roof, the intermediate posts will become the frame for the side walls.
When performing this work, maintain a certain pitch of the beams. Set its size at the design stage.
After installing the rafters, attach the ridge. It is placed along their upper edge. Metal corners or brackets are used for fastening. And the most popular are bolts.

Rigidizing the structure

After installing the gable roof rafter system, strengthen it using the technology presented below:

For small buildings, such as saunas, cottages, utility buildings, and roofs with a simple hanging rafter system, connect each pair of rafters from below using a tightening, and from above using a crossbar.
For large buildings that are also lightweight, choose a light roof. The walls must support it.
If the house is 6-8 m wide, then the structure should be strengthened. Place the support in the middle. Such racks are called headstocks. Place them at each pair of rafter legs.
If the span of the walls reaches 10 meters, then reinforcing beams will be needed. The struts act as additional support for the rafter legs for tightening. They are attached to each rafter - closer to the ridge or in the middle of the rafter leg. Fasten them to the lower end of the headstock and to each other, as shown in the video about the gable roof rafter system.
In situations with long roofs, the gable beams should be relieved. This is done by installing braces. The top end should rest against the corner of the gable. The lower one is mounted on the central floor beam. For fastening, use a beam that has a large cross-section. This way you can prevent them from breaking if there are strong gusts of wind.
In areas where winds prevail, the rafters must be resistant to such influences. Strengthen them by installing diagonal braces. The boards are nailed from the bottom of one rafter to the middle of the next.
For greater rigidity, when creating the most critical fastenings, it is better not to use nails. Use pads for this and metal methods fasteners Nails will not be able to provide high-quality fastening, since the wood can dry out after some time.

Lathing of the rafter system

The final stage of installing a gable roof rafter system is the creation of sheathing. It is on this that you will lay the roofing covering. Carry out the work in the following sequence:

Select dry timber for sheathing. There should be no cracks or knots on it. Nail the beams from below. Attach two boards near the ridge so that there are no gaps. The sheathing must withstand the weight of the upper roofing material and not bend under the weight of the workers.
If you are installing a soft roof, make two layers of sheathing. One is sparse, the second is continuous. The same applies to roll roofing. To begin, place boards parallel to the ridge beam that are 25 mm thick and no more than 140 mm wide. A small gap is allowed - no more than 1 cm. Place a continuous layer on top. For this it is better to use roofing plywood, slats or boards of small thickness. After this, check that there are no errors left on the sheathing - irregularities and knots. Also check that there are no nail heads sticking out.
Place one layer of timber under the metal tiles. It should have a cross section of 50 by 60 mm. Proceed in the same way when using slate or steel roofing sheets. Maintain a step between the beams, depending on the roofing you choose - from 10 to 50 cm. Hammer the nails closer to the edges of the board, and not in the middle. Drive the hats in deep. This way they won’t be able to damage the roof later. If you are making sheathing for metal tiles, then remember that the connection of the timber at the same level should fall on the rafter.

When you have installed and strengthened the rafter system of the gable roof, you can begin installing the roofing pie. Place between rafters thermal insulation material, a layer of vapor barrier and waterproofing. When using insulation in slabs, calculate in advance the pitch of the rafters for its installation. At the final stage, attach the roofing material.

The rafter system of any object is equivalent to the value of the load-bearing structural elements of the house. The roof plays the role of a node under which the stiffening ribs of the building are assembled. Accordingly, when installing a roof with your own hands, you need to pay maximum attention to all structural units, even when using simple option- gable.

Advantages of gable roofs

There are a lot of options for pitched rafter systems. Among them, the simple symmetrical one is especially popular. Why? Here are its advantages:

Variations are created on the basis of a gable roof to reflect the special architecture of the building.
Simple calculations that are easy to understand.
One-piece design creates favorable conditions for dry interior space and unhindered flow of water, snow and ice.
The maintainability, strength and wear resistance of a gable roof are much higher than other options.

Depending on the size, homeowners always have the opportunity to equip the under-roof space, turn it into a full floor or attic. In a word, a gable roof is the correct and profitable solution for any object, be it a residential building, a summer house or a bathhouse.

Elements of the rafter system

Depending on the type of roof, the structural elements vary. Without knowledge of the purposes of each, it is impossible to arrange reliable coverage for your home. Let's look at it in detail:

Mauerlat

The basis of the rafter system. It is a beam with a cross-section of at least 150 mm, or an I-beam channel if the roof structure is metal. It is located on the load-bearing walls of the facility. Its purpose is to distribute the load of the system evenly throughout the entire structure of the house.

Rafter leg

The structural basic unit of a system. Together with others, it forms a truss system - strengthening the strength of the entire roof. It is made of wooden beams, not inferior in cross-section to the Mauerlat or profile pipes.

Rafter stand

Vertical beam or pipes. Depending on the gable roof option, the racks can be located in the center and/or sides. They take part of the weight of the entire rafter system, which is why the cross-sectional size is 150 mm.

Rafter purlins

Horizontal beams laid on the posts and under the ridge to support the rafter legs. They provide rigidity to the structure and relieve stress on the trusses.

Tightenings and struts

Connecting beam for rafters. The action is similar - relieving the tension of timber or metal and imparting rigidity to the structure.

Lezhny

Installation support for posts and struts. To reliably connect these two elements, a large cross-section beam is required - 150 mm or a thick-walled pipe of impressive diameter.

Lathing beam

Elements laid perpendicular to the rafters. They are used to install the selected roofing covering and create a multi-layer protective pie. The cross section is small - 40–50 mm.

If the intended roof structure is made of wooden beams, you should carefully consider the quality of wood when purchasing - the timber should not have any knots and be made of soft wood.

Also, the wood must have natural moisture, otherwise it will begin to dry right in the structure of the system, cracking, deforming the roof model, depriving it of reliability and safety.

Calculation of the rafter system

A gable roof is a complex structure. The project takes into account many factors - natural nuances, wind, constant and variable loads. It is extremely difficult to make calculations on your own, without special knowledge about the climate of the area, the characteristics of the material for the manufacture of the system, and the nuances of pressure distribution.

Ideally, the calculations are left to professionals; you can choose only the coating material yourself - the following parameter depends on its type:

Tilt angle

The minimum angle of inclination of the roof relative to the parallel of the ground is 5 degrees. However, its dependence comes from the selected roofing material. For this purpose, traditional slate, corrugated sheets, flexible and metal tiles are used.

They are guided by the following rule: the steeper the slope, the more textured the roof can be.
From 5 degrees for laying rolled protective roof insulation. The number of layers matters - up to 15 degrees three-layer coatings, above - two- and single-layer.

From 6 – ondulin.
From 11 – slate.
From 12 – corrugated sheets.
From 14 to 20 – metal tiles.
From 15 to 45 – soft roofing.

Thus, the resulting precipitation - snow, water - will not linger on the surface, although complete cleaning requires your own efforts or the involvement of specialists to install the Anti-Ice system.

Determination of rafter parameters - pitch, length, cross-section

The smaller the step, the more impressive the cross-section of the timber or the diameter of the pipes should be. As a rule, for load-bearing structures, this parameter is at least 150 mm, 100 mm - for country houses and related construction - gazebos, bathhouses, outbuildings.

Next, you need to set the number of rafters per slope: its length is divided by the installation step, ranging from 60 to 100 cm + 1 outer leg. Multiply the result by 2 to get the total quantity. Depending on the cross-section of the beam, the amount of rafter legs and the installation pitch vary.

The length of the rafters is simply calculated if the school knowledge about the right triangle remains in your luggage. The rafter leg is equal to the hypotenuse of the resulting figure. The calculation is as follows: A² + B² = C², where – A is the height of the roof, B is half the length of the pediment, C is the length of the rafter leg. To the resulting value always add from 30 to 70 cm for the eaves overhangs.

Types of rafter systems

Before getting to work, it is important to choose a rafter system option for a gable roof. There are few of them, each has its own advantages and disadvantages:

Hanging

Suitable only for a standard roof width of 6 m, which is the length of the rafter leg. Fastening occurs by fixing the ends to the ridge girder and load-bearing wall. Be sure to install a tightening that levels out the tension and pressure of the structure.

In addition, they will play the role of load-bearing beams. Without them, the structure will corrode under the weight. The advantages of this option are the absolute dryness of the roof surface during the off-season, and less deformation at the time of shrinkage.

Layered

The option is suitable for any roof width. Reliability and stability are ensured by fixing the bed to the Mauerlat. Thus, the pressure is leveled by the stand, causing the tension in the rafter legs to decrease. The advantage of the system is its simplicity, but the design requires large investments - additional lumber is required to arrange the beds.

Hybrid

These systems are typical for multi-slope roofs, where the transitions are accompanied by numerous reinforcements, beams, posts, beams, slopes and other elements for the stability of the entire structure. The device is expensive and complex, so only a professional should be involved in the design and construction. At least supervise it.

Do-it-yourself gable roof installation

So, when the rafter system option has been selected, lumber has been purchased, a roof design has been drawn up, you can begin to work. You cannot deviate from the sequence of stages. This threatens to delay installation and loss of structural reliability.

Mounting the Mauerlat

If the length of the timber for installing the Mauerlat is not enough, extensions are made. The ends are connected using the half-tree cutting method. Additional fasteners are anchor bolts. Do not use screws, dowels or nails - they are unreliable. Mounting to the wall is as follows:

A distance from the edge of at least 5 cm is maintained.
Holes are drilled along the wall to insert fasteners. Similar actions are carried out with timber.
The Mauerlat is attached to the edge using steel pins. The fastening step is often 2 times the distance between the rafter legs. Subsequently, before installing the main units, they are guided by metal marks.

Important - before laying the mauerlat, the edge of the wall is protected with waterproofing. Spread one layer even if the house is made of wood.

Manufacturing and fastening of rafters

Roof trusses are convenient because they can be assembled on the ground in finished design and move it to the roof. This will reduce installation time, however, the model is heavy and lifting equipment will be required, which, naturally, will increase the cost of the project.

For budget construction Another method is suitable:

A cut is made at the bottom and top of the rafter legs to connect to the mauerlat and ridge girder. This must be done separately with each unit, after first lifting the wood to the top.
Places for fixing are marked on the Mauerlat and a ridge girder is installed: racks are installed along the gables, on which the timber is placed. If the length is not enough, it is increased, but in a different way, unlike the Mauerlat - a board is screwed onto the joint on both sides.
Depending on the chosen model of the rafter system - layered, hanging - cuts are made in the ridge beam, mauerlat, or holes are drilled in them for fastening.
Next, they begin installing the rafter legs from opposite ends of the roof, gradually moving towards the middle. It’s a good idea to pull a cord between the corners of the outer trusses to ensure that the entire horizontal part matches exactly.
The rafter legs are connected to each other by ties and struts. Under the ridge part, at the angle formed by the rafters, wooden overlays are stuffed, and the ends themselves are tightened with bolts.

More recently, professional builders have begun to use sliding fasteners to install roofing. Metal plates securely hold the load-bearing elements and at the same time move due to shrinkage. This neutralizes its consequences.

The work of fastening the rafters is hard and long. You should calculate the time in advance - you cannot leave the roof unfinished during the rainy season, otherwise the rigidity of the structure will be lost in the future due to absorbed moisture.

Pediments and sheathing

The side parts of the roof - gables, are made in the form of ready-made panels from boards and are completely installed at the top. There shouldn’t be any difficulties - it’s just important to carefully cut them at the required angle. It is necessary to fasten the sheathing only after it is known final look roofing covering. For example:

Under corrugated sheeting, the pitch of the sheathing beam will be 440 mm.
The metal tiles are fixed to the sheathing in increments of 350 mm.
A soft roof requires a continuous plywood covering.

It is important to note the places for the passage of the chimney - the sheathing should not come into contact with the brick or metal surface. The distance to the hot unit is at least 15 cm. Before installing the sheathing finished roof covered with waterproofing with allowances extending beyond the edges of the walls. Then the timber is installed.

If you decide to make an insulation cake from above, then first strengthen the vapor barrier from the inside, then put the selected material into the boxes formed by the rafters. Next, waterproofing and wind protection.

Then you need to again mark the contours of the rafter legs with a 20*20 beam and then fill in a new layer of sheathing, along which the roofing material will be laid - formation ventilation ducts. This method will preserve the capacity of the under-roof space if the owners intend to use it for a specific purpose.

Flooring roofing material

Regardless of the type of roofing material, installation begins from the edges of the roof and goes up, placing one unit on top of another. This way, rain moisture will not get under the material.

The method of fastening depends on the type of material - soft tiles or tiles with a bitumen or polymer base are fused. Solid profiled sheets - ondulin, metal tiles - are fixed into pre-drilled holes to the sheathing, using rubber linings to seal and preserve the anti-corrosion layer.

As a result: a description of the installation of the rafter system and roof is easy only on a screen or paper. In reality, the process is complex and multifaceted. Therefore, if knowledge is not enough, it is better to invite professionals to work - their work is always guaranteed.