Gable roof: 3 stages of construction

Mauerlat is fixed approximately like this:

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

This is how the crate is attached:

One of the simplest roof structures 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.

Gable roof construction

Types of truss systems

The gable roof is one of the oldest. It is represented by two flat slopes, which are closed in the upper part along one line. The lower edges of the slopes rest on the walls of the house, which are usually on the same level.

The end parts of the roof of gable structures are two vertical triangle-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 you can reduce the load on the base.

Roof slopes can be located at different angles. If the angle is large enough, then under the roof you can equip the attic room. 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 a different angle of inclination.

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

1. Rafters are made when the house has a central load-bearing wall. At its end, racks are installed on which the running beam is attached. It is this run that serves as a 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 an offset ridge and slopes of different sizes, located at different angles.

2. hanging rafters mounted in the absence of a central supporting structure. The rafter legs are connected to each other without an upper run, relying on each other (and on the ridge beam). To increase rigidity, intermediate elements are added to the structure - puffs and linings that prevent the rafter legs from moving apart.

The choice of truss 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 work is the calculation of the main parameters of the frame of the future roof. There are three ways to go here:

1. Take advantage of a ready-made solution, making the truss system an exact copy of the frame of an already built roof. Ideal for typical houses, but it is not always possible to find a suitable copy for copying.
2. Use an online calculator for the calculation of the truss structure. Option suitable for preliminary calculation and evaluation of various options. The calculators that I have worked with are quite accurate, but there is a risk of not taking into account something.

3. Do your own calculations. To do this, use the formulas based on SNiP 2.01.07-85 "Loads and Impacts" and other regulatory documents. This option is the most difficult, but also the most reliable.

Full self-calculation of loads is very time-consuming. I will describe the main steps.

First, we need to determine the load on the roof:

1. Weight load calculation - the area of ​​\u200b\u200bthe slopes is multiplied by the specific gravity of the roofing pirogue. This value consists of the mass of the crate, waterproofing, insulation and roofing material, and averages from 40 to 50 kg / m².

2. Snow load calculation - We multiply the normative snow load for your region by a coefficient that depends on the angle of the slope. If the slopes are located at an angle of 60 °, then this coefficient is taken equal to zero, if 30 ° - to one. Intermediate values ​​are calculated by the formula µ = 0.033 (60 - α), where α is the slope angle.

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

3. Wind Load Calculation - the normative wind pressure in the region is multiplied by the correction factor for the height of the building and by the aerodynamic coefficient (for strength, it is desirable to take the minimum value - 0.8). Wind pressure standard is 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	Section 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

The obtained values ​​are summarized, obtaining the final value of the load on the roof.

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

Qr=A Q, Where:

• QR - load on the rafter leg, kg / m.;
• A - step of rafters, m;
• Q - total load per square meter of roof, 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 Rbend)), Where:

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

Calculation example:

We 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 pine boards of the first grade 5 cm wide, the total load on the roof (weight + snow + wind) is 300 kg / m².

1. QR \u003d 0.8 300 \u003d 240 kg / m.
2. H \u003d 9.5 2.8 sqrt (240/5 140) \u003d 15.4 cm.

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

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

Equipment for work

Materials used

Based on the calculation, it is possible to purchase parts for the frame, battens, insulation, waterproofing and roofing material. The indicative list of materials includes the following items:

Illustration	Material
	Details for the truss 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. Also here you can include bars or logs for support posts (when installing a layered system), Mauerlat and ridge beam. The ideal material for the manufacture of all these elements is well-dried pine wood of the first or second grade.
	Framing details. Sheathing and counter-sheathing is a fairly light frame that is mounted on top of the truss system for mounting roofing material. It is made either from slats with a section of 30x30 or 20x40 mm, or from a board from 25 mm, or from plywood at least 15 mm. The choice of type of lathing is determined by the roofing material.
	Roof insulation. Mounted on the underside of the slopes. Most often, slabs 75-150 mm thick based on mineral wool are used for roof insulation.
	Waterproofing. It is best to purchase special roofing membranes (Ruvitex, Tyvek and similar) that combine water resistance with vapor permeability. Due to this, condensate will not collect in the under-roof space, and the insulation will not suffer from moisture.
	Roofing material. Here the choice is huge. Gable roofs can be covered: metal tile; professional flooring; · flexible tiles; · ceramic tiles; slate (standard and polymer), etc.
	Additional elements of the roof. This includes parts that are used for installation in areas experiencing increased operational loads.Most often, a set of additional elements includes: skating bars; cornice strips; end strips; slats adjoining vertical surfaces; spotlights, etc.
	Drainage system. It can be made of galvanized steel, polymer-coated metal or plastic. It is represented by a fastening system, gutters along the perimeter of the roof, receiving funnels and downpipes.

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

1. Rolled waterproofing materials (roofing material) for laying at the point of contact of the truss system with the walls of the building.
2. Fasteners (nails, self-tapping screws, anchors, studs with fixing nuts, etc.).
3. Metal plates and brackets to reinforce the attachment points of wooden elements.
4. Adhesive tapes for joining rolled materials.
5. Impregnation for wood - antiseptic and reducing flammability.

Set of tools

For the construction of the rafter system, the installation of the crate and the laying of the roofing, the following tools will be needed:

1. A saw on a tree (preferably several, and different ones - a miter saw for the main trimming, a circular saw for smaller jobs, a reciprocating saw or a hacksaw for fitting).
2. Carpenter's axes (yes, cutting grooves is still more convenient to do with a good ax).
3. Perforator with drills according to the material from which the load-bearing walls are composed.
4. Drill with a set of drills.

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

Since you will have to work at a height, you can not do without several ladders, scaffolds and scaffolding for building material.

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

Roof installation

Stage 1. Installing the Mauerlat

We begin to mount the gable roof frame with the installation of a support beam - Mauerlat. For its manufacture, we take a bar 100x100 or 150x150 mm from dry pine wood.

We mount the Mauerlat according to the following scheme:

Illustration	Sequencing
	Preparing the end of the wall. At a wooden house, the upper crown acts as a Mauerlat. At 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 a solution.
	Waterproofing. At the junction of concrete / brick and Mauerlat we lay waterproofing roll material - roofing material or its analogues. This will protect the wood from destruction under the influence of capillary moisture.
	Mauerlat laying. We lay the support beam on the end of the wall and carefully align it so that it lies without protrusions and distortions.
	Drilling for fasteners. We drill holes in the Mauerlat and the supporting wall for the installation of anchors. Drilling is carried out in two steps: first, we pass a wooden beam with a drill, and then we make a nest in the wall fence with a puncher with a drill. When working with structures made of porous concrete, we use special drills, since impact drilling can lead to the formation of cracks.
	Fastener installation. We insert anchors with a thickness of 10 m or more into the holes and deepen them with hammer blows.
	Final fix. We screw the fixing nuts of the anchors.In this case, the anchor sleeve expands, securely fixing it on the base.

This is not the only way to fix the Mauerlat on the wall railing. Sometimes steel studs with a thickness of 12 mm or more are embedded in brick or blockwork, and a beam with drilled holes is put on them and fixed with nuts with wide washers. This method is more reliable, but also more time-consuming - you need to lay the studs in advance, even at the stage of building the supporting structure.

Stage 2. Installation of racks, run and rafters

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

Illustration	Sequencing
	Bed laying. We lay a beam on the central load-bearing wall, which will serve as a support for the racks and the run. We fix the beam on the base in the same way as the Mauerlat - with mandatory reinforcement, waterproofing and fixing with anchors.
	Run installation. We connect the upper parts of the gables with a long longitudinal beam - a run. If the pediments are a continuation of the main walls, then we rely on the run on vertical racks installed close to the pediment parts.
	Rack installation. With a step equal to the selected step of the rafters, we install vertical racks connecting the run and the bed. We set the racks according to the level, and at the top and bottom we must fix them with steel corners and fix them with self-tapping screws.
	Preparation of rafter legs. We cut the boards intended for the manufacture of rafters to size, if necessary, level them with a planer. We breed concentrated impregnation for wood (antiseptic + flame retardant) and process future rafters from all sides. Dry the impregnated wood thoroughly.
	Rafter marking. We attach the rafter legs to the frame (the lower part rests on the Mauerlat, the upper part on the run) and fix it with clamps to the temporarily stuffed bars. With the help of a square, we mark where you need to make a cutout for attaching the rafters.
	Rafter laying. According to the markup, we make cutouts using a hacksaw or reciprocating saw. We put the rafter legs in place, carefully aligning. If necessary, we correct the edges of the cutout with a carpenter's ax.
	Docking at the top. We cut the upper ends of the rafter legs so that they fit with a gap of no more than 1-2 mm. We fix the rafters on the run with metal corners. We connect both parts with a steel plate with a thickness of at least 1.5 mm.
	Bottom fastening. We fix the base of the rafter leg on the Mauerlat by drilling a diagonal hole and twisting a long self-tapping screw there. When installing rafters from a wide board with a small thickness, you can also use metal corners made of steel with a thickness of 2 mm.
	Installation of the lower puffs. At the bottom of each truss truss, we mount long transverse boards, each of which should connect the left rafter, the post and the right rafter. We set the boards according to the level, fixing each with at least two self-tapping 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,
	Installing top ties. We fasten the upper puffs in exactly the same sequence. They should be located exactly under the run.
	Trimming rafters. We cut the edges of the rafters, forming vertical and horizontal surfaces for mounting cornice strips. It is very important to trim all the slope rafters at the same level, therefore we carefully take all measurements before starting the operation.
	Butt decoration. We fill the frontal 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 put a narrow board with a thickness of 20 mm or more into it and fix it with self-tapping screws. This board will serve as the basis for installing drippers.

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

Stage 3. Installation of the crate, waterproofing and roofing

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 not so large-scale, but still time-consuming.

Main stages:

1. Installation of waterproofing. On the rafters we horizontally roll out the rolls of the waterproofing membrane, fixing it directly to the rafter legs with the help of galvanized brackets. We lay the waterproofing with an overlap (from 100 to 300 mm, the greater the slope angle, the less overlap). The joints of the panels must be glued.

In places where ventilation and chimney pipes pass through the roof, as well as along the ridge, we lay additional waterproofing.

2. Installation of the crate / counter-crate. Additionally, we fix the waterproofing material by stuffing wooden bars along the rafter legs with a section of at least 30x30 mm.On top of these bars, we mount the crate under the roofing material - slats, boards or plywood sheets. For fixing the crate, we use wood screws.

3. Thermal and vapor barrier of the roof. On the inside, between the rafters, we lay heat-insulating mats that minimize energy loss through the slopes. If the price of mineral wool turns out to be unbearable, foam plastic can also be used - 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 transverse bars or sheathing made of plywood or chipboard.

4. Installation of the selected roofing material. We start work from the perimeter, installing eaves and end strips. Then we mount the roofing material on the slopes, trying not to damage the waterproofing during installation. We fix the roofing sheets to the crate.

5. Installation of additional elements. We install additional elements of the roof - a ridge strip that overlaps the junction of the slopes in the upper part, the strips adjoining the chimneys and ventilation, etc.

6. Installation of a drainage system. We fix fasteners for gutters to the frontal board or to the end parts of the rafters. We mount gutters along the slopes with a slope towards the receiving funnels. At the edges we put funnels, from which we lower the drainpipes down.

Conclusion

A gable roof is just the option from 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.

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