Online calculator gable roof will help you calculate the angles of inclination of the rafters, the required amount of sheathing, the maximum load on the roof, as well as the materials required to build a roof of this type with given dimensions. You can calculate the roofing from such popular roofing materials as slate, ondulin, ceramic, cement-sand and bitumen shingles, metal tiles and other materials.
The calculations take into account the parameters given in TKP 45-5.05-146-2009 and SNiP “Loads and Impacts”.
A gable roof (also known as a gable or gable roof) is a type of roof that has two inclined slopes that run from the ridge to the outer walls of the building. This is the most common type of roof today. This is explained by its practicality, low construction costs, effective protection premises and aesthetic appearance.
Rafters in the structure gable roof lean on each other, connecting in pairs. On the end side, gable roofs have the shape of a triangle; such ends are called gables or gables. Usually, an attic is installed under such a roof, which is illuminated using small windows on the gables (attic windows).
When entering data into the calculator, be sure to check additional information, marked with an icon.
At the bottom of this page you can leave feedback, ask your own question to the developers, or suggest an idea to improve this calculator.
The rafters and roof slope are inclined at this angle. It is understood that it is planned to build a symmetrical gable roof. In addition to calculating the angle, the calculator will inform you how the angle complies with the standards for the roofing material you have chosen. If you need to change the angle, then you need to change the width of the base or the height of the roof, or choose a different (lighter) roofing material.
Total roof area (including overhangs of a given length). Determines the amount of roofing and insulating materials that will be needed for the work.
Total weight roofing material, necessary for full coverage roof area.
Total insulating material in rolls, which will be required for roof insulation. The calculations are based on rolls 15 meters long and 1 meter wide.
The maximum load on the rafter system. The calculations take into account the weight of the entire roofing system, roof shape, as well as wind and snow loads the region you specified.
The full length of the rafters from the beginning of the slope to the ridge of the roof.
The total number of rafters required to construct a roof at a given pitch.
The table shows the recommended dimensions of rafter sections (according to GOST 24454-80 Lumber coniferous species). To determine compliance, the type of roofing material, the area and shape of the roof structure, and the loads placed on the roof are taken into account. The adjacent columns display the total weight and volume of these rafters for the entire roof.
The total number of rows of sheathing for the entire roof. To determine the number of rows of sheathing for one slope, it is enough to divide the resulting value by two.
To install the sheathing evenly and avoid unnecessary overspending, use the value indicated here.
To sheath the entire roof, you will need the number of boards indicated here. For calculations, a standard 6-meter board length is used.
The volume of boards in cubic meters will help you calculate the cost of sheathing.
Estimated total weight of sheathing boards. The calculations use average values of density and moisture content for coniferous wood.
Beautiful and reliable.
What is the basis of any roof?
How correctly the parameters of the elements are calculated rafter system, will depend on how strong and reliable the roof is.
Therefore, even at the stage of drawing up the building design, a separate calculation of the rafter system is performed.
It is impossible to perform the calculation correctly if you do not take into account the intensity of the various loads that will affect the roof of the house at different periods.
Factors influencing the roof are usually classified into:
And it is difficult for a beginner to do it, since many factors that affect the roof must be taken into account.
Indeed, in addition to the above factors, it is also necessary to take into account the weight of all elements of the rafter system and fastening elements.
Therefore, special calculation programs come to the aid of calculators.
To find out the load on the rafters of our house, we must first calculate the weight roofing pie.
This calculation is easy to do if you know total area roofing and materials that are used to create this very pie.
First, count the weight of one square meter pirogue.
The mass of each layer is summed up and multiplied by a correction factor.
This coefficient is equal to 1.1.
Here is a typical example of calculating the weight of a roofing pie.
Let's say you decide to use ondulin as a roofing material.
And that's true!
After all, ondulin is reliable and inexpensive material. It is for these reasons that it is so popular among developers.
So:
Let's sum up the data obtained: 3+5+10+15= 33 kg.
Now the result must be multiplied by 1.1.
Our correction factor.
The final figure is 34.1 kg.
This is the weight of one square meter of roofing cake.
The total roof area is, for example, 100 square meters. meters.
This means that she will weigh 341 kg.
This is very little.
This is one of the advantages of ondulin.
The moment is very important.
Because in many areas in our winter a fairly decent amount of snow falls.
And this is a very large weight, which must be taken into account!
To calculate the snow load, a snow load map is used.
Determine your region and calculate the snow load using the formula
In this formula:
— S is the desired snow load;
— Sg is the mass of snow cover.
The weight of snow per 1 square meter is taken into account. meter.
This indicator is different in each region.
It all depends on the location of the house.
A map is used to determine the mass.
— µ is the correction factor.
The indicator of this coefficient depends on the angle of inclination of the roof.
If the angle of inclination of the slopes is less than 25 degrees, then the coefficient is equal to 1.
At an inclination angle of 25 - 60 degrees, the coefficient is 0.7.
If the angle of inclination is greater than 60 degrees, then the coefficient is not taken into account.
For example, a house was built in the Moscow region.
The slopes have an inclination angle of 30 degrees.
The map shows us that the house is located in the 3rd district.
Mass of snow per 1 sq. meter is 180 kg.
We carry out the calculation, not forgetting about the correction factor:
180 x 0.7 = 126 kilograms per 1 sq. meter of roof.
To calculate wind loads, a special map broken down by zones is also used.
Use this formula:
Wo is a standard indicator determined from the table.
Each region has its own wind tables.
And the k indicator is a correction factor that depends on the height of the house and the type of terrain.
Calculating the length of the rafter leg is one of the simplest geometric calculations.
Because you only need two dimensions: width and height, and the Pythagorean theorem.
To make the calculation more clear, look at the figure below.
We know two distances:
- a is the height from the bottom to the top point of the inside of the rafters.
First leg;
- b is the quantity equal to half roof width.
Second leg.
- c is the hypotenuse of the triangle.
c²=(2 x 2)+(3 x 3).
Total c²=4+9=13.
Now we need to get the square root of 13.
You can, of course, take Bradis tables, but it’s more convenient to use a calculator.
We get 3.6 meters.
To this number you now need to add the extension length d to get the required rafter length.
The cross-section of the boards that we will use for the manufacture of rafters and other elements of the rafter system depends on how long the rafters are, at what pitch they will be installed and on the magnitude of the snow and wind loads that exist in a particular region.
For simple designs use a table standard sizes and board sections.
If the design is very complex, then it is better to use special programs.
The distance between their bases is called.
Experts believe that minimum distance should be 60 cm.
And the optimal distance is 1 meter.
We calculate the distance between the rafters:
For example, the length of the roof slope is 12 meters.
We first select a rafter pitch of 0.8 meters.
12/0.8 = 15 meters.
We add the unit 15+1=16 rafters.
If the result was a fractional number, we would round it up.
Now 12 meters should be divided by 16.
As a result, 1216 = 0.75 meters.
Here optimal distance between the rafters on the same slope.
The table mentioned earlier can also be used.
For wooden beams the optimal span is from 2.5 to 4 meters.
The optimal cross-section is rectangular.
Height to width ratio 1.4:1.
The beam must extend into the wall at least 12 cm.
Ideally, the beams are attached to anchors that are pre-installed in the wall.
Waterproofing of beams is carried out “in a circle”.
When calculating the cross-section of beams, the load from its own weight (usually 200 kg/sq. meter) and operational live load are taken into account.
Its value is equal to the constant load - 200 kg/sq. meter.
Knowing the span and the installation pitch of the beams, their cross-section is calculated from the table:
| Span (m)/ Installation pitch (m) | 2.0 | 2.5 | 3.0 | 4.0 | 4.5 | 5.0 | 6.0 |
| 0.6 | 75x100 | 75x150 | 75x200 | 100x200 | 100x200 | 125x200 | 150x225 |
| 1 | 75x150 | 100x150 | 100x175 | 125x200 | 150x200 | 150x200 | 175x250 |
If a more accurate calculation is required, then use Romanov’s calculator.
A pitched roof is the simplest roofing option.
But this option is not suitable for every building.
And rafter calculations are required in any case.
Calculations for a pitched roof begin with determining the angle of inclination.
And it depends, first of all, on what material you plan to use for the roof.
For example, for corrugated sheets minimum angle equals 8 degrees.
And the optimal temperature is 20 degrees.
If online calculators perform simple calculations, then special software can calculate everything you need.
And there are quite a lot of such programs!
The most famous of them are 3D Max and AutoCAD.
Such programs have only two drawbacks:
There are a number of free programs.
Most programs can be downloaded to your computer.
Or use them online.
Video about calculating rafters.
We offer a professional free calculation of the gable roof truss system using online calculator website, 3D visualization and detailed drawings. Detailed calculations of the roof and roofing, all materials, sheathing, rafters, mauerlat. Try calculating a gable roof right now!
Our online calculator rafter system will calculate the gable roof:
- calculating the length of gable roof rafters
- number of rafters and pitch
- calculation of gable roof area and angle of inclination
- calculation of roof sheathing
- number of sheet roofing materials (for example, corrugated sheets, metal tiles, slate)
- vapor barrier and insulation parameters
To generate a gable roof calculator calculation, you need to measure and enter the following dimensions in the appropriate boxes:
The cross-section (thickness x width) and pitch of the rafters depend on the angle of inclination of the roof, its type, the length of the rafter leg, the maximum main loads that can be withstood, as well as the type and weight of the roof covering, and even to some extent on the width of the insulation. If you don't know where to get it standard parameters rafters and sheathing, our article will help you “ Optimal cross-section, sheathing pitch and rafter legs depending on roof type ».
The calculator calculates the materials for the roof, based on the dimensions of the roofing sheet you entered and the calculated roof area. We recommend buying the quantity of roofing materials for the roof, boards and beams for the rafter system with a small reserve; it is always better to hand over the remainder to hardware store than to pay a lot of money for delivery of a missing pair of boards.
Be careful! The online calculator will be able to calculate a gable roof depending on how accurate the values you enter.
Simplify your calculations and save time, the program will draw the rafter plangable roof and will display the results of calculating a gable roof based on the data you entered in the form of a drawing of a gable roof from different viewing angles, and its interactive 3D model.
On the tab " 3 D- View"You can better see your future gable roof in a three-dimensional view. In our opinion, visualization in construction is a very necessary opportunity.
If your project has a gable roof with different slopes, you should make the calculation using the calculator twice - for each slope separately.
X- width of the house
Y- roof height
C- overhang size
B- roof length
Y2- extra height
X2- extra width
The program works in two modes: a simple gable roof and a roof with two side gables (side roofs), type 1 and type 2.
Attention! If you have a roof with one side gable, then for the calculation use first type 1, then type 2. And from the data obtained, calculate the amount of building materials: rafters, sheathing boards, roofing and sheet materials.
Otherwise there may be an error in the calculation. After all, the program takes into account the cutouts in the main roof for the roofs of the side gables.
In the calculation you will see several numbers: the size or volume of building material for half the roof and in brackets - full size or volume.
In counting additional roof- the full size and volume, and two numbers in parentheses: the size and volume of one and two additional roofs.
Attention! When calculating sheet roofing material, keep in mind that the program calculates by roof area.
For example, 2.8 rows times 7.7 sheets per row. During actual construction, 3 rows are laid.
To more accurately calculate the number of roofing sheets, you need to reduce the sheet height in the calculation until you get a whole number of rows.
Don't forget to set the amount of overlap more precisely.
When calculating the volume of material for the rafters of the main roof, in mode type 2, the program does not take into account the cutout for the side gable. This is due to some implementation difficulties in the program.
Maybe I'll solve this in the future.
However, the excess rafter material is unlikely to disappear, or make some adjustments to your calculations.
There will also be a separate program for more intelligent calculation of sheet roofing materials.
And don't forget what to buy Construction Materials it is necessary with some reserve for waste.
A roof is not only about protecting your home from external environment, but also a certain decorative element that gives the structure a finished look. That is why developers today are building the most unusual roofs with complex structures rafter systems.
The rafter system is the most important element arrangement of any roof. It bears the weight of the coating and precipitation. That's why correct execution Such a system, taking into account all the rules of construction art, is a guarantee of the reliability and durability of the roof. It is very important to correctly determine the length of the rafters and other structural elements. In this case, it is necessary to take into account such climatic features as:
Any structure of this kind is carried out in the form of interconnected elements that strictly correspond to the previously made calculations. The following elements can be distinguished as part of this system:
Note! It is necessary to take special responsibility when calculating the length of the rafters - any, even minor, mistake can lead to deformation of the roof geometry and, accordingly, its collapse.
If you don't understand the features roofing structure, then it is better to contact a qualifiedm specialists. For self-calculation ispUse special calculators and tables - this will help you avoid mistakes.
Rafter systems are divided into two groups depending on the material used:
There are also reinforced concrete rafter systems, but they are used mainly in industrial buildings. In any case, whether the rafters are metal, wood or concrete, they must be firmly attached to the walls of the house.
Often for the construction of rafters in country houses They use wood, mainly coniferous. Compared to metal, wood is easier to process and install. Moreover, even if an error occurred during the calculations, then wooden parts easy to replace.
Before you start calculating, first measure the width of the house. The fact is that although small slanted legs do not require additional building, in some cases the special geometry of the roof requires reinforcement of the rafters, even if the house is of small size.
According to the design features, rafters are divided into:
In construction country houses Sloping rafters are more often used, but often builders combine both. As mentioned, extensions of the mowed legs may be required. This depends on the roofing material used during construction. Thus, slate or ceramic tiles, due to their large weight, can only be installed on a rafter system of increased strength.
The cross-section of the boards used in the construction of the rafters can be 20x6 cm or 15x5 cm. But if the structure is strengthened, you can choose a beam withO larger cross-section (there is another way of strengthening - by splicing boards).
And now - directly to the calculations.
First, let's define the fundamental points.
Note! Distance between load-bearing walls called a run. As the run increases, the number of changes in the design increases, in particular, the number of stabilizing and reinforcing elements.
Now, having familiarized yourself with the starting points, you can take paper, a ruler and a pencil and start making calculations.
First, determine how much the roof itself will weigh. This is very important, because the rafter system must withstand this weight for a long time. It is very easy to calculate: find out the weight per square meter of each layer, summarize the data obtained and add a correction of 10%.
Here is an example of such calculations.
Let's see what happens.
15 + 3.5 + 6 + 10 = 34.5 kg.
Add the correction 10%, it turns out 37.95 kg. This figure is an indicator of the weight of the roofing cake.
Note! In most cases, this weight does not exceed 50 kg, but experienced specialists are confident that when making calculations, it is necessary to base their calculations on precisely this value – “for reserve”.
It turns out that the weight of the roofing cake should be 50 + 10% = 55 kg/m².
It is very important to take into account the snow load, because snow can accumulate on the roof for quite some time. large quantities. Use a special formula to determine this load:
µ x Sᶢ = S, Where
SV in this case– this is the snow load that you need to calculate;
µ – correction depending on the slope of the slope;
U flat roof, the slope of which does not exceed 25°, the correction will be equal to unity; if the slope of the slope is more than 25°, but does not exceed 60°, then the correction will be 0.7. If a very steep roof is being built, then the snow loads for it can not be calculated at all.
Sᶢis the weight of a square meter of snow cover. This indicator depends on the climatic characteristics of a particular region; you can find out about it in SNiP.
Calculation example
Let’s say the roof slope is 25°, and the snow mass is 200 kgf/m².
0.7 x 200 = 140 kgf/m²
This is the planned snow load on the rafter system.
To calculate wind load on rafters, use the formula below.
K x Wᵒ = W, Where
Wᵒin this case, it is a standard indicator that you must determine from the table (it all depends on what region you live in);
TO- This is an amendment that takes into account the height of the house and the type of terrain.
Table 1. Wind loads in Russia
Table 2. Correction factor standards.
|
House height, m |
||
|
0,75 |
||
|
0,65 |
||
|
1,25 |
0,85 |
In this case, A is open areas, and B is areas evenly covered with obstacles.
Calculation example
Let's say you want to build a house five meters high in the Moscow region. This region is located in I windy area, so the wind load here is 25 kgf/m². Amendment – 0.5. Let's see what happens:
0.5 x 23 = 11.5 kgf/m²
To calculate the length of the rafters, you can remember geometry at school, namely the famous Pythagorean theorem. After all truss structure- this is, in essence, right triangle and measuring its diagonal is very simple. But do not forget to take into account when calculating:
Note! According to GOST, rafters should not bend more than 1/250 of their length. For example, if the length of the rafters is 5m, then multiply this numbero by 0.004 - this way you will get the maximum deflection, namely 2 cm.
To calculate the cross section, use the table below.
Table 3. Calculation of the cross-section of the rafter system
|
Rafter length, m |
Distance between rafters, m |
Required beam cross-section, cm |
|
Less than 3 |
8x10 |
|
|
Less than 3 |
9x10 |
|
|
Less than 4 |
8x16 |
|
|
Less than 4 |
8x18 |
|
|
Less than 4 |
9x18 |
|
|
Less than 6 |
8x20 |
|
|
Less than 6 |
10x20 |
Calculation example
Let's say the length of the rafters is 4 m. From the table we see that for this length there are three section options available, depending on the pitch of the rafters. If this step is, for example, 14 m, then the work will require a beam with a section of 8x18 cm.
According to GOST, wood must meet the following requirements:
In addition, when purchasing bars, pay attention to:
Judging by everything said above, to calculate rafters you need to have not only a sufficient supply of knowledge, but also drawing and drawing skills. Of course, not every one of us can boast of all this.
Fortunately, today there are many computer utilities designed to make calculations easier. There are professional ones among them, such as, for example, AutoCAD, but you can find more simple options. So, in the Arkon program you can easily create various projects, and also clearly see what the future roof will look like.
Note! Such utilities also have a calculation calculator, which was mentioned earlier. With its help, you can calculate the length, pitch and cross-section of rafters with extreme accuracy.
Such calculators are also available online, but all the data that can be obtained with their help is advisory in nature and does not replace a full-fledged drafting of the project.
One of the most important stages roof construction is the calculation of the rafter system. Of course, it is better to entrust this matter to professionals, but preliminary measurements can be made on your own - this will help you understand the finished drawing.
