Many private households become much more attractive if you add a gable roof with an attic to the project. This is a good idea to use free space under the roof. You will get not only the design and architectural attractiveness of the house, but also additional rooms for living. But drawing up a project is fraught with many problems - for example, you need to correctly calculate the roof and choose a convenient device. It is about how to make an attic with a gable roof, we will tell in our article. But we’ll touch on a broken structure a little, as it is one of the common ones.
Features of the roof with an attic
The attic is such a structure in which people live. Its purpose, frankly, is specific. Therefore, the roof will have such features:
- The shape of the roofing system will be special, it is very different from the "classic".
- In the roof you have to make a large number of windows.
- A full-fledged heat-insulating layer is being developed, which allows for comfortable living of people inside.
- Be sure to have to lay internal communications in the attic.
In the article we will present projects of houses with a gable roof and an attic, which are most often used by people during construction. But you always need to remember that, in addition to standard projects, there are individual ones - they can always be ordered from the architect, but you will have to pay a certain amount.
The design of the roof truss system
The most important element of the attic is the rafter structure. If you do it right, you can not only correctly implement the attic arrangement, but also ensure the normal operation of the whole house. If you focus on practice, you can equip the attic floor in any type of roof. In the article we presented a photo of houses with a gable roof with an attic. You can also see the broken roof structure and see the differences between the two systems.
Depending on the project of the building, even a single-pitched roof structure can be used. The use of hip or multi-panel roofs is also allowed. In other words, it all depends on your capabilities, desire and project. It is still worth noting that the design of a broken rafter system has several advantages - it allows you to increase the free space under the roof due to the fact that the angle of inclination changes.
Such an option would be almost ideal, unless you take into account the high construction costs. Increases, and significantly, the consumption of materials. But it is impossible not to mention that technically it is more difficult to execute such a roof than a simple gable roof. In its design there are such elements:
- Skate and side rafters.
- Lathing of ridge and side rafters.
- Struts.
- Racks.
Rafters are hanging and inclined. The latter are used if intermediate load-bearing walls are present in the project. In other words, one of the sides of the rafters should abut the Mauerlat on the outside, and the second on the inside wall. As for the hanging rafters, they have two tiers - the lower (side) and upper (ridge). In order to give rigidity to the structure, racks and jumpers are installed.
Where to start the construction of the attic roof?
It should be noted right away that the calculation of the attic under a gable roof is the first step that must be completed before starting work. Usually the construction of the attic is included in the general plan of work. But sometimes homeowners change the roof and at this stage they realize that they want something more from their home.
For example, increasing the space for living. In order to properly organize construction work, you need to develop a drawing and plan. And subsequently you need to clearly follow these documents. Let's start from the very beginning - with the calculation of the attic.
How to calculate the attic floor parameters
It is necessary to adhere to a certain sequence when calculating a gable roof with an attic. The rules are as follows:
- In the first step, you need to choose the scheme of the rafter structure.
- Now you need to calculate the parameters of the attic room.
- Calculate the quantity of materials and maximum permissible loads.
- Draw up a detailed construction plan.
Be sure to carefully approach all calculations so that all indicators are calculated correctly. Otherwise, the integrity of the structure during operation may be impaired.
How to calculate the indicators
When calculating the attic plan and putting it into practice, an important place is taken by how correctly all the indicators were found. First you need to find the value of the attic floor area. Pay attention to what sizes are most optimal for him:
- Floor height - 2 m.
- The optimal width is 3 m.
If you make a mansard room with such dimensions or more, you will ensure a comfortable stay in it. Be sure to determine the dead area of the floor. The article provides a photo of the attic of a gable roof and a broken line. They have differences, in particular, in the usable floor area.
The basic rule when calculating usable area is that you need to consider the distance from the bend of the ceiling to the floor surface. A value of 0.9 m or more is recommended. The rest of the attic floor can be considered deaf, it is simply irrational to use it for living.
To perform the calculation of the roof area, it is necessary to add the corresponding values of the individual elements. In other words, if the attic is under a gable roof, then you need to add up the area of two slopes. If the structure is broken and symmetrical, then you need to add the area of the ridge and side slopes, and then multiply by 2. In the photo of the attic with a gable roof, you can see what are the differences from the broken structure.
And now let's talk about how to calculate the parameters of the rafter system:
- Calculate the angles of inclination of the side and ridge rafters.
- You calculate the amount of material that is necessary for the manufacture of the rafter system (ridge and side parts).
- Define the parameters of the crate.
- Consider how much material you need to spend to make a crate.
- Combine all the data and make a complete list of materials.
And at the last step, you will have to calculate the cost of materials. It all depends on the size of the structure and version. You also need to consider the cost of manufacturing - if you will hire workers, then get ready to give at least 75% of the cost of the material.
Rafters
When drafting the attic with a gable roof, you need to take into account the angle of inclination of the side elements. Of course, it all depends on the particular house and the value can be any. For example, when calculating the angle of inclination of the lateral rafters of a sloping roof, you need to take its minimum value of 60 degrees. When calculating, you should rely on the following methods:
- The simplest and most reliable is geometric. In carrying out the calculations, it is sufficient to use the Pythagorean theorem.
- Reference books can be used to determine the angle of inclination.
- A technique based on geometric constructions. In this case, a plan is built on a scale, then all the necessary parameters are calculated.
- You can use construction calculators that are offered by companies involved in the installation of the roof.
If you decide to install a broken roof, then you must adhere to the angle of inclination of the ridge rafters at 30 degrees. This is the most optimal value. In the manufacture of an attic with a gable roof with your own hands, this value is not taken into account. We will talk about the parameters of the gable structure further.
How to calculate the roof area
In order to purchase roofing material, insulation, lathing, panels for decoration, you need to make the correct calculation of the roof area. For convenience, you need to break the entire surface into simple components. So, in the case of a gable roof, it is necessary to break it into two identical elements. To calculate the area of one, you need to multiply the length by the width. Multiply the resulting value by 2 and get the total surface area.
But this is for the case when you are making a gable roof on a house with an attic. If you decide to make a broken roof, you will have to break the entire surface into 4 sections. To calculate the area of one slope, you need to add the corresponding parameters of the side and ridge parts. The total value of the area can be obtained by multiplying this result by 2.
Calculation of the area of the attic room
The parameters of the attic floor are determined by how much space the room has on it. In order to calculate the area, you need to determine the line of the walls. To calculate the area, you need to multiply the length of the room by its width. If the walls of the attic room pass along the lines of the racks, then you need to resort to a different calculation method. It is necessary to multiply the length by the distance between opposite pillars.
If the room has a complex shape, then you need to divide it into simpler sections (triangles, squares, rectangles) and first calculate their area. Then all the obtained values need to be summed.
How to calculate the mass of roofing material
Of course, the accuracy of the calculations is quite low, but the approximate mass can still be calculated. These data will be useful to you when calculating the maximum load and choosing the material for the rafter system. So, 1 square. m has such a mass:
- Soft types of tiles - from 9 to 15 kg.
- Slate - from 11 to 13 kg.
- Metal - from 5 to 6 kg.
- Ceramic tiles - from 50 to 60 kg.
- Galvanized sheet - from 3 to 6.5 kg.
How much insulation material is needed
When warming the attic of a gable roof , both rolled and plate materials can be used. Use bulk (for example, expanded clay) is not worth it. We will focus on roll materials, as they are most convenient to use. When carrying out the calculation, it is necessary to take into account an overlap of 10 cm. Standard sizes of rolled insulation: in length - 10-15 m, in width - 1 m.
Be sure to find out before buying what sizes the material actually is. Depending on which manufacturer, sizes may vary. After all, the manufacturing specifications are different for all manufacturers. Knowing the size of the roll, you can calculate its area. To find the number of rolls, you need to divide the roof area by a similar amount of insulation material. But a supply is needed - do not forget about the overlap.
How to calculate the load on the rafters
It is necessary to take the average value of the load - about 200 kg per linear meter. If you make a rafter taking into account this load, your roof will be able to withstand the effects of wind and snow. When carrying out calculations, it is recommended to use reference data and tables with coefficients of snow and wind loads. For example, in various regions of our country, the load created by snow (maximum) may be 220 kg or a little more. 220 kg is the average value for all regions of the Russian Federation.
When carrying out calculations of a specific design, it is necessary to take into account correction factors, which depend on the angle of inclination of the roof:
- More than 60 degrees - the coefficient does not need to be taken into account.
- 25-60 degrees - a ratio of 1.25.
- Less than 25 degrees - coefficient 1.
Therefore, when calculating the load created by the snow layer, it is necessary to take into account both the average value (220 kg) and the correction factors. So, if the angle of the ridge is 30 degrees, then you need to multiply 220 by a factor of 1.25. It will turn out 275 kg per square meter.
When calculating the length and width of the roof, you need to use the simplest mathematical formulas. To make the calculations easier, divide the entire structure into simple components.
Rafter lengths
In the device of a gable roof with an attic there are rafters. They are located directly on the walls of the house. Be sure to make a take-out outside the walls of the order of half a meter. See an example of a gable roof design with an attic.
The attic room is highlighted in the picture. H is the height from the surface of the room floor to the ridge, L is the length of the rafter leg. The extension beyond the outer walls is 0.5 m. To find L, you need to use the Pythagorean theorem (you should get a triangle). But you need to know the length of the two legs - this data is in the project. The article also contains photos of the inner attic. Projects with a gable roof are the most attractive, as they are easier to manufacture. For example, you have a height of 3 m, and the second leg is also 3 m. The formula for calculating this is:
L 2 = H 2 + A 2
L = (H 2 + A 2 ) 1/2
L = (9 + 9) 1/2
L = 4.24 (m).
A slightly different calculation of the broken structure. This is due to the fact that the shape of the rafters is slightly different. The system also contains ridge rafters.
How many rafters do you need?
When calculating the number of rafters, you need to consider what linear dimensions the house has, as well as what roof area. Be sure rafters are installed at the same distance. Standard rafters made of wood with a cross section of 50 x 100 mm are mounted at a distance of 70-80 cm. Provided that the leg length is more than 6 m. If the leg length of the rafters is 3-6 m, then they should be placed at a distance of 1.2 m.
When calculating sloping and gable roofs, the following parameters must be adhered to - the cross-section for both side and ridge elements should be from 50 x 100 mm. When calculating, you need to take the average density of the tree at a relative humidity of 18%. This is 500 kg per 1 cubic meter. m
Crate
But not everything is taken into account, before you make an attic with a gable roof, you need to calculate the amount of material for the crate. Consider the following data:
- For a soft type of roofing material, you can make a crate of OSB-plates or plywood.
- If semi-rigid materials are used, it is best to mount a compacted or sparse crate.
- If the roofing material is hard (for example, slate), you need to do a sparse crate.
- For semi-rigid large-sized material, a continuous crate must be made.
In order to find the number of rows, you need to use the following recommendations:
- For a roof with a small slope (less than 12 degrees), you need to make a continuous crate.
- With a slope of less than 60 degrees, the crate must be laid in increments of 0.2-0.23 m.
- If the slope is more than 60 degrees, then the crate is mounted in increments of 0.6 m.
Usually equip a crate of edged boards with a width of 0.2 m. They are laid at a distance of 0.2-0.3 m from each other.
How many rows of crate?
So, let's say you decide to use a trim board of 200 x 20 mm for the manufacture of the battens, and the distance between adjacent rows is 200 mm. Therefore, on one meter, three rows of crates must be laid. But if you increase the distance between adjacent rows (for example, make 300 mm)? On one meter only two rows will fit. If you are calculating a broken system, then you will need to add two more rows - a cornice and a ridge.
The distance between the rows must be maintained the same, so that the strength is maximum. After all, it is necessary to take into account the fact that the whole system must withstand both the mass of roofing material and the effects of snow and winds. And most importantly - with the same distance between the rows of the battens, you will be able to mount the heat-insulating pie with the highest quality.
The number of boards for the manufacture of lathing
Lumber is used standard, for the manufacture of crates, you can use both hardwood and coniferous species. Standard lumber:
- Of conifers - length 4.5 and 6 m.
- Of hardwood - not more than 5 m.
- Of conifers for special needs - 9 m long.
Based on this, we can say that for a house of 8 x 10 m on a slope of a roof 10 m long, two boards of 6 m are needed. It is necessary to take into account a ledge of at least 20 cm
But after all, all boards are usually sold not in pieces, but in cubic meters. To find the volume, follow these steps:
- Count the number of boards needed to make the crate.
- Convert all linear dimensions to meters for further calculations.
- Multiply the number of boards by all sizes of one.
For example, you need 10 identical boards 200 x 20 mm in size and 6 m long. 200 mm is 0.2 m, 20 mm is 0.02 m. You need to find the product 0.02x0.2x6x10 = 0.24 (cube m).
The total mass of wood from which the crate is made can also be calculated and this will not be difficult. So, with a relative humidity of 18%, a cubic meter has such a mass:
- Norway spruce - 450 kg.
- Cedar pine - 440 kg.
- Common pine - 510 kg.
- Siberian fir - 380 kg.
- Caucasian Fir - 440 kg.
– 500 1 . . , 10 ( ), 0,24 500 = 120 . .
( ) . , . , . , , – 4,5 6 .
, . , . , "" .