Gable roof: calculation, features, drawings and design

Roofing is an important element of any building. Its main purpose is to protect the internal space of the house from unfavorable factors of the external environment. It takes on all possible external loads and evenly distributes them to all walls. Buildings on buildings can be roofed with different designs. But in Russia the most popular is, of course, a gable roof. The calculation of such a construction is simple. Advantages of it are the simplicity of design and erection.

Essential elements

There is such a roof, as already can be judged by its name, only of two ramps located on both sides of the building. The main elements of the roof of this design are:

• Mauerlat;
• Horse;
• Rafters;
• Racks and struts;
• Crate.

The gable roof is usually built in the following order:

1. The mauerlat is attached to the anchors pierced first into the walls.
2. The rack is mounted on the rack.
3. Rails and struts are installed.
4. Mounted crate.

Further, the resulting structure is covered with a thermal insulation material, a waterproofing sheet and roofing sheets.

What is important to consider when designing

Thus, the gable roof construction is extremely simple. However, the project before the assembly of the roof is, of course, follows. This will avoid overspending and save time and effort.

When drawing a draft of a gable roof, the calculations are usually performed as follows:

• The angle of inclination of the rays;
• Length and section bars for rafters;
• Step between the rafters.

In order to determine the right amount of insulation, waterproofing and roofing material, you will also have to calculate the area of skates and pediments. It is with all these indicators taken into account that the roof of the gable roof is calculated.

Limit values of the angle of inclination

It is from the angle of the slope of the skates and you should start calculating a gable roof when building a house. To depend on this indicator in this case can from several factors:

• The type of roofing material chosen for the cladding;
• The estimated wind load;
• Snow load.

In the first case, the manufacturer's recommendations are taken into account. So, for example, the minimum angle of inclination:

• For metal, it will be 14 degrees;
• For roll materials - 5 - 15 gr;
• Profiled sheeting - 15 gr;
• Onduline - 6 g.

Depending on the wind and snow load, the maximum permissible values of the angle of inclination of rays are determined by special maps of the localities. Also in this case, special tables are used. For example, with strong wind loads, it is recommended to make the steep slopes 15-25 degrees. With an abundance of precipitation in the area where the house is built, on the contrary, it is necessary to equip them with steeper ones - 45-60 degrees.

Roof rafters: calculation of slope angle

So, having learned the maximum permissible parameters, you can proceed with the actual drawing of the roof drawing. First of all, you need to determine the height of the skate. If it is decided to make a common loft under a gable roof, it is not worthwhile to lift the hobby too high above the level of the walls. This will save on the material. If it is planned to build a residential building under the roof (which is rare), it is worthwhile to build it high enough. In any case, the optimal indicators of the angle of inclination of rays in most parts of Russia are 30 - 45 degrees.

In addition to the height of the ridge, to calculate the slope of the gable roof, or rather the angle of inclination of its rays, you need and such an indicator as the width of the pediment. It can be determined by simply measuring the short wall of the house, then you need to add the length of the overhang to the result. The calculation is then carried out using the following formula: H = 1 / 2L * tgA. A is the angle of the slope proper, H is the height of the ridge, and L is the width of the pediment. Tangent angle can be determined using the mathematical table of Bradys.

Calculation of rafters gable roof: length and section

It is these elements in the construction of the gable roof are the main ones. Calculate the cross-section and length of the rafters first of all, proceeding from the fact that the weight of materials per 1 m ^{2 of} the ramp area should not exceed 45 kg.

Most often, for the construction of a gable roof, a 100 x 150 cm bar is used. This material will be ideal for a step between rafters of 80-100 cm. If the project between the two elements provides a longer distance, it is worthwhile to use a thicker beam. At a smaller step, on the contrary, it is allowed to install rafters thinner.

The length of the bar is determined depending on the height of the ridge and the width of the pediment (divided by 2). Rafters in this case in a rectangular triangle will play the role of a hypotenuse. Determine the length of the beam is not difficult. You can also calculate the length of one bar, simply by orienting yourself on the angle of the slope of the gable roof. In this case, in addition, you need an indicator such as the height of the location of the ridge. This figure will simply need to be multiplied by the sine of the angle of inclination. You can find this figure from the Bradys table.

To the result obtained in the final result should be added about 20 - 40 cm to overhangs. It is necessary to equip them. Otherwise in the future, when operating the house, rainwater will fall on its walls. And this, in turn, will significantly shorten the life of the building.

The lumber for rafters should only be selected for quality. It is this element of the roof that is the carrier. Bars with a large number of knots for rafters can not be used. Mount these elements to the maule and skate follows with the use of only galvanized corners or high-quality nails.

Calculation of the area of skates and the amount of material required

In this way, the slope of the gable roof, the length and section of its rafters are calculated. But in order to determine the amount of material necessary for plating, you need to know more and such an indicator as the area of skates. In this case, no particularly complicated formulas will also be used. You can find out the area of one ramp by simply multiplying the length of the rafters by the length of the building itself.

It is not difficult to determine when designing and the amount of material necessary for plating. For example, when using a ruberoid, you first need to calculate the area of one roll. To do this, multiply its width by the length. Further, the area of the slope is simply divided into the area of the roll. When calculating in this case, you also need to take into account the expected number of layers of skin. Also, calculations are also made when using sheet materials, for example, metal or corrugated board.

Calculation of the area of the gables

This part of the roof structure is usually covered with boards. For the calculation of gable roof gables you need indicators such as the height of the ridge and the width of the span of the house. Having determined the area of this part of the roof structure, it will be possible to find out the number of boards necessary for the plating. The calculation in this case is made using the formula: S = 1 / 2ah, where S is the area, a is the width of the pediment, and h is the height of the ridge.

Helpful advice

Having made the calculation of the area of skates and pediment, it is not difficult to determine the amount of material necessary for plating. However, it is necessary to purchase roofing sheets and boards with a margin. After all, when covering the roof part of the material is bound to be spoiled. Waste in such a business is usually unavoidable. Yes, and cut the boards or sheets as rationally as possible is not always.

Features of the construction of a gable roof: how to avoid mistakes

Thus, having correctly drawn up the project and having carried out all the necessary calculations, the roof can be built as reliably as possible. However, in order for the roof of two rays to be durable, certain recommendations should be observed and directly when assembling it:

• Before the insulation layer in the roofing pie, ventilation must necessarily be arranged;
• The slabs of the heat-insulating material must be adjacent to each other and the structure of the rafter system as tightly as possible;
• The vapor barrier film in the cake is fixed with adhesive tape and not with nails;
• The crate must be packed with a step corresponding to the selected material.

Collecting the roof in order to make it reliable, it follows, without violating any technology. The roof pie of the gable roof is mounted as follows:

1. Between the installed rafters are laid insulation plates. From the attic side, in order that they do not fall out, a rare grid of steel or aluminum wire is stretched.
2. Above the heater is mounted waterproofing. Fasten it best with a slight slack on the bars. Such a method will avoid the rupture of the material during the movements of the roof, and also equip the ventilation layer.
3. Over the waterproofing is mounted crate.

Steam insulation of the gable roof is arranged from the attic side. Over the film, fixed tape, mounted covering material. This can be, for example, plywood, lining, plastic panels, etc.

Basis for roofing material

To calculate the crate in the design of a gable roof, factors such as the weight of the roofing material and the possible snow load should be taken into account. Under the metal, for example, the supporting boards can be packed in steps of 230 - 400 mm. Under the roofing felt, the crate is equipped with a solid crate, and so on.

Lumber for the base under the roofing material is also selected taking into account the weight of the latter. For the assembly of the battens, both the timber and the board can be used. In any case, it is not recommended to take too wide sawn timber for mounting the base. Otherwise, the elements of the crate can be twisted during operation of the roof. Also, wide boards often crack, which can make the fastening of the sheets of the cladding material not too reliable. The best option for a crate is a bar or boards with a width of 150 mm.