Before you start building a roof, it is of course desirable that it be designed for strength. Immediately after the publication of the last article ““, I began to receive questions in the mail regarding the choice of the cross-section of rafters and floor beams.
Yes, understanding this issue in the vastness of our beloved Internet is indeed quite difficult. There is a lot of information on this topic, but as always it is so scattered and sometimes even contradictory that an inexperienced person, who in his life may not even have encountered such a subject as “Sopromat” (lucky someone), can easily get confused in these wilds.
I, in turn, will now try to create a step-by-step algorithm that will help you independently calculate the rafter system of your future roof and finally get rid of constant doubts - what if it won’t hold up, or what if it will fall apart. I will say right away that I will not delve into the terms and various formulas. Well, why? There are so many useful and interesting things in the world that you can fill your head with. We just need to build a roof and forget about it.
The entire calculation will be described using an example. gable roof, which I wrote about in
So, Step #1:
Determine the snow load on the roof. To do this, we need a map of snow loads in the Russian Federation. To enlarge the picture, click on it with the mouse. Below I will provide a link where you can download it to your computer.
Using this map, we determine the number of the snow region in which we are building a house and from the table below we select the snow load corresponding to this region (S, kg/m²):
If your city is located on the border of regions, choose higher value loads. There is no need to adjust the resulting figure depending on the angle of inclination of the slopes of our roof. The program we will use will do this itself.
Let's say in our example we are building a house in the Moscow region. Moscow is located in the 3rd snow region. The load for it is 180 kg/m².
Step #2:
Determine the wind load on the roof. For this we need a map of wind loads in the Russian Federation. It can also be downloaded from the link below.
Using this map, we also select the corresponding region number and determine the wind load value for it (the values are shown in the lower left corner):
Here, column A is the open coasts of seas, lakes and reservoirs, deserts, steppes, forest-steppes and tundra; Column B - urban areas, forests and other areas evenly covered with obstacles. It should be taken into account that in some cases the type of terrain may differ in different directions(for example, the house is located on the outskirts of a populated area). Then select the values from column “A”.
Let's return to our example again. Moscow is located in I-th wind region. The height of our house is 6.5 meters. Let's assume that it is being built in locality. Thus, we accept the value of the correction factor k=0.65. Those. wind load in in this case will be equal to: 32x0.65=21 kg/m².
Step #3:
You need to download to your computer a calculation program made in the form of an Excel table. We will continue to work in it. Here is the download link: ". Also here are maps of snow and wind loads in the Russian Federation.
So, download and unpack the archive. Open the file “Calculation” rafter system", and we get to the first window - “Loads”:
Here we need to change some values in the filled cells blue. All calculations are done automatically. Let's continue with our example:
In the “Initial Data” plate we change the angle of inclination to 36° (whatever angle you have, write that, well, I think this is clear to everyone);
We change the pitch of the rafters to the one we chose. In our case it is 0.6 meters;
Load roof (self-weight load roofing material) — we select this value from the table:
For our example, we choose metal tiles with a weight of 5 kg/m².
Snow. region - here we enter the sum of the values of snow and wind loads that we received earlier, i.e. 180+21=201 kg/m²;
Insulation (mans.) - we leave this value unchanged if we lay insulation between the rafters. If we do cold attic without insulation - change the value to 0;
We enter in the “Lathing” sign required dimensions sheathings. In our case, for metal tiles, we will change the pitch of the sheathing by 0.35 m and the width by 10 cm. We leave the height unchanged.
All other loads (from the own weight of the rafters and sheathing) are taken into account by the program automatically. Now let's see what we got:
We see the inscription “The load-bearing capacity of the sheathing is ensured!” We don’t touch anything else in this window; we don’t even need to understand what the numbers are in other cells. If, for example, we choose a different rafter pitch (more), it may turn out that the load-bearing capacity of the sheathing will not be ensured. Then it will be necessary to select other dimensions of the sheathing, for example, increase its width, etc. In general, I think you will figure it out.
Step #4:
Sling.1"and go to the window for calculating rafters with two support points. Here, all the input data we previously entered is already entered by the program automatically (this will be the case in all other windows).
In our example from the article “Do-it-yourself gable roof of a house,” the rafters have three support points. But let’s imagine that there are no intermediate posts and let’s do the calculation:
On the rafter diagram we change the length of its horizontal projection (the cell is filled in blue). In our example, it is 4.4 meters.
In the “Calculation of rafters” plate, change the value of the rafter thickness B (specified) to what we have chosen. We set 5 cm. This value must be greater than that indicated in the cell Tue (stable);
Now in the line " We accept N"We need to enter the selected rafter width in centimeters. It must be greater than the values indicated in the lines " Ntr.,(strong)" And " Ntr., (deflection)". If this condition is met, all the inscriptions at the bottom under the rafter diagram will look like “Condition met.” In the line " N, (by variety)" indicates the value that the program itself offers us to choose. We can take this number, or we can take another. We usually choose sections available in the store.
So, what we got is shown in the figure:
In our example, to meet all the strength conditions, it is necessary to choose rafters with a section of 5x20 cm. But the roof diagram I showed in the last article has rafters with three support points. Therefore, to calculate it, we move on to the next step.
Step #5:
Click on the tab " Sling.2" or " Sling. 3″. This opens a window for calculating rafters with 3 support points. We select the tab we need depending on the location of the middle support (rack). If it is located to the right of the middle of the rafter, i.e. L/L1<2, то пользуемся вкладкой "Sling.2". If the post is located to the left of the middle of the rafter, i.e. L/L1>2, then use the tab "Sling.3". If the stand is exactly in the middle, you can use any tab, the results will be the same.
On the rafter diagram, we transfer the dimensions in cells filled with blue (except for Ru);
Using the same principle as described above, we select the cross-sectional dimensions of the rafters. For our example, I took the dimensions 5x15 cm. Although 5x10 cm was also possible. I’m just used to working with such boards, and there will be a larger margin of safety.
Now it is important: from the drawing obtained during the calculation, we will need to write down the value of the vertical load acting on the post (in our example (see figure above) it is equal to 343.40 kg) and the bending moment acting on the post (Mop. = 78.57 kghm). We will need these numbers later when calculating the racks and floor beams.
Next, if you go to the “ Arch“, a window will open for calculating the rafter system, which is a ridge arch (two rafters and a tie). I won’t consider it; it’s not suitable for our roof. We have too large a span between the supports and small angle slope of the slopes. There you will get rafters with a cross section of about 10x25 cm, which is of course unacceptable for us. For smaller spans such a scheme can be used. I am sure that those who understand what I wrote above will understand this calculation themselves. If you still have questions, write in the comments. And we move on to the next step.
Step #6:
Go to the “Rack” tab. Well, everything is simple here.
We enter the previously determined values of the vertical load on the stand and the bending moment in the figure in the cells “N=” and “M=”, respectively. We recorded them in kilograms, we enter them in tons, and the values are automatically rounded;
Also in the figure we change the height of the rack (in our example it is 167 cm) and set the dimensions of the section we have chosen. I chose a 5x15 cm board. At the bottom in the center we see the inscription “Central secured!” and “Off-center.” secured." So everything is fine. The safety factors "Kz" are very large, so you can safely reduce the cross-section of the racks. But we will leave it as it is. The calculation result in the figure:
Step #7:
Go to the tab "Beam". Floor beams are subject to both distributed and concentrated loads. We need to take both into account. In our example, beams of the same section span spans of different widths. Of course, we make calculations for a wider span:
— in the “Distributed load” plate we indicate the pitch and span of the beams (from the example we take 0.6 m and 4 m, respectively);
— we take the values Load (normal) = 350 kg/m² and Load (calc.) = 450 kg/m². The values of these loads in accordance with SNiP are averaged and taken with a good margin of safety. They include the load from the dead weight of the floors and the operational load (furniture, people, etc.);
- in the line " B, given» enter the section width of the beams we have chosen (in our example it is 10 cm);
In the lines " N, strength" And " N, deflection» the minimum possible cross-sectional heights of the beams will be indicated at which it will not break and its deflection will be acceptable. We are interested in the larger of these numbers. We take the height of the beam section based on it. In our example, a beam with a cross section of 10x20 cm is suitable:
So, if we didn’t have racks resting on the floor beams, the calculation would have ended there. But in our example there are racks. They create a concentrated load, so we continue to fill out the “” and “ Distributed + concentrated«:
In both plates we enter the dimensions of our spans (here I think everything is clear);
In the “” plate, we change the values of Load (normal) and Load (calculated) to the figure that we received above when calculating rafters with three points of support - this is the vertical load on the rack (in our example, 343.40 kg);
In both plates we enter the accepted width of the beam section (10 cm);
The height of the beam section is determined by the sign “ Distributed + concentrated." . Again we focus on a larger value. For our roof we take 20 cm (see figure above).
This completes the calculation of the rafter system.
I almost forgot to say: the calculation program we use is applicable for rafter systems made of pine (except Weymouth), spruce, European and Japanese larch. All wood used is 2nd grade. If you use other wood, some changes will need to be made to the program. Since other types of wood are rarely used in our country, I will not describe now what needs to be changed.
The roof of a house is a load-bearing structure that takes on all external load (weight roofing pie, its own weight, the weight of the snow cover, etc.) and transmits it to everything load-bearing walls at home or on internal supports.
In addition to its aesthetic and load-bearing functions, the roof is an enclosing structure, separating it from external environment attic room.
The basis of the roof of any house is the rafter system.
This is the frame to which the roof is attached.
All loads are taken by this skeleton.
The rafter system consists of:
When all these elements (except for the Mauerlat) are connected to each other, a roof truss is obtained.
The basis of such a truss is a triangle, which is the most rigid of the geometric shapes.
The main element of the roof frame is the rafters.
Before you begin directly calculating the rafters, you should find out what loads will affect the roof of the house.
That is, on the rafter legs.
Loads acting on the roof frame are usually divided into constant and variable.
Constant loads are those loads that act constantly, regardless of the time of day, season, etc.
This is the weight of the entire roofing cake, the weight additional equipment, which can be installed on the roof (fencing, snow retainers, aerators, antennas, etc.).
Variable loads appear at certain times of the year.
For example, snow.
When snow falls on the roof, this is a very decent weight.
In any case, it should be taken into account.
It's the same with the wind.
It's not always there, but when it blows strong wind, a fairly large wind force acts on the roof frame.
And an inexperienced person is unlikely to succeed.
It's worth a try though.
Just remember when calculating a large number of various factors affecting the roof.
At least the weight of the rafter system itself with all the elements and fasteners.
Therefore, professionals use special tools to calculate rafters. computer programs and calculators.
How to find out the load on the rafter legs?
The collection of loads should begin with determining the weight of the roofing pie.
If you know what materials will be used and the area of the slopes, then it’s easy to calculate everything.
It is customary to calculate how much 1 weighs square meter roofs.
And then multiply by the number of squares.
Let's calculate the weight of a roofing pie as an example.
The roofing material is ondulin:
We sum up all the weights: 3+5+10+15= 33 kg.
Then the value obtained as a result of the calculations should be multiplied by a factor of 1.1.
This is a correction factor.
It turns out 34.1 kg.
How much does 1 sq. meter of our roofing cake.
And if total area our roof is 100 square meters, then it will weigh 341 kg.
Snow load calculationThere is a snow load map.
It shows the amount of snow cover in each region.
We calculate the snow load using the following formula: S = Sg x µ.
Sg is the mass of the snow cover.
µ—correction factor.
And this coefficient depends on the angle of inclination of the slopes of your roof.
The larger this angle, the less value this coefficient.
At tilt angles greater than 60 degrees, it is not used at all.
Since snow does not collect on the roof.
Calculating wind load
Just as the whole country is divided into regions according to the mass of snow, it is also divided according to the strength of the winds.
And there is also a special map on which the wind strength is indicated in each area.
To calculate wind loads, use the formula:
Wo - indicator taken from the map.
k is an adjustment factor depending on the type of terrain where the building is located and its height.
The cross-section of the rafters depends on three factors:
Knowing these parameters, it is easy to determine from the table.
Of all the types of roofs, the shed roof is the simplest.
There are no complex elements in it at all.
And it is installed on load-bearing walls that have different heights.
This kind of roofing is installed on garages, bathhouses, and utility rooms.
To calculate what the length of the rafters will be pitched roof, you should decide on the angle of inclination.
And the angle of inclination of the slope depends, first of all, on the type of roofing material that you want to use.
In the case when it is corrugated sheeting, the optimal angle of inclination is 20 degrees.
But it is prohibited to make an angle less than 8 degrees!
Otherwise, in the cold season, the roof will not withstand the weight of the snow cover and will simply fail.
If you are laying metal tiles, then minimum angle the tilt increases to 25 degrees.
When using slate - 35 degrees.
If the roof is seam, then the angle of inclination can be different: 18 - 35 degrees.
After you have figured out the angle of the slope, you need to raise the back wall to such a height that you get the desired angle.
The most difficult thing in such calculations is to find the sine and tangent.
But for this they use the following sign:
| Roof angle, degrees | Tangent tgA | Sine sinA |
|---|---|---|
| 5 | 0,09 | 0,09 |
| 10 | 0,18 | 0,17 |
| 15 | 0,27 | 0,26 |
| 20 | 0,36 | 0,34 |
| 25 | 0,47 | 0,42 |
| 30 | 0,58 | 0,5 |
| 35 | 0,7 | 0,57 |
| 40 | 0,84 | 0,64 |
| 45 | 1,0 | 0,71 |
| 50 | 1,19 | 0,77 |
| 55 | 1,43 | 0,82 |
| 60 | 1,73 | 0,87 |
For example, let's find the length of the rafters and the height of the facade wall for a house 5 meters long.
The tilt angle is 25 degrees.
To determine the height of the front wall, Lbc x tg 25 = 5 x 0.47 = 2.35 meters.
Accordingly length rafter leg Lc = 2.35 x 0.42 = 5.6 meters.
And do not forget to add to the resulting length the length of the front and rear overhangs, which are necessary in order to provide the walls of the building with protection from slanting rain.
On average, the length of one overhang is 0.5 meters.
If required, this length can be longer.
But less than 0.5 meters is impossible.
This means that 1 meter should be added to the length of the rafter: Lc = 5.6 + 1 = 6.6 meters.
Rafter system gable roof much more complex than the rafter system of a shed roof.
There are more elements, and the principle of its operation is somewhat different.
To calculate the length of the rafter leg, we use the Pythagorean theorem. 
If you look at the picture shown right triangle, then you can see that the hypotenuse b is our rafter.
And its length is equal to the length of the leg divided by the cosine of the specific angle of inclination of the slopes.
For example, if the width of the house is 8 meters, and the angle of inclination of the slopes is 35 degrees, then the rafter leg will have the length:
b= 8 / 2 / cos 35 = 8 / 2 / 0.819 = 4.88 meters.
Now all that remains is to add the length of the canopy, approximately 0.5 meters, to get the required length of the rafters.
It should be said that these are simplified versions of rafter calculations.
In order to obtain the most accurate data, it is best to use special programs.
For example, free program"Arkon".
The built-in calculator, based on the parameters specified by you, will itself calculate both the cross-section of the rafter leg and the length of the rafter.
Video about the rafter calculation program.
We present a free calculator for gable roof calculations. Online calculation of the sheathing, the angle of the rafters and the required amount of materials.
Specify roofing material:
Select a material from the list -- Slate (wavy asbestos cement sheets): Medium profile (11 kg/m2) Slate (corrugated asbestos cement sheets): Reinforced profile(13 kg/m2) Corrugated cellulose-bitumen sheets (6 kg/m2) Bituminous (soft, flexible) tiles (15 kg/m2) Galvanized sheet metal (6.5 kg/m2) Sheet steel (8 kg/m2) Ceramic tiles (50 kg/m2) Cement-sand tiles(70 kg/m2) Metal tiles, corrugated sheets (5 kg/m2) Keramoplast (5.5 kg/m2) Seam roofing (6 kg/m2) Polymer-sand tiles (25 kg/m2) Ondulin (Euro slate) (4 kg/m2) m2) Composite tiles (7 kg/m2) Natural slate (40 kg/m2) Specify the weight of 1 square meter of covering (? kg/m2)
kg/m2
Enter roof parameters:
Base width A (cm)
Base length D (cm)
Lifting height B (cm)
Length of side overhangs C (cm)
Front and rear overhang length E (cm)
Rafters:
Rafter pitch (cm)
Type of wood for rafters (cm)
Working area of the side rafter (optional) (cm) ">
Lathing calculation:
Sheathing board width (cm)
Sheathing board thickness (cm)
Distance between sheathing boards
F (cm)
Snow load calculation:
Select your region using the map below
1 (80/56 kg/m2) 2 (120/84 kg/m2) 3 (180/126 kg/m2) 4 (240/168 kg/m2) 5 (320/224 kg/m2) 6 (400/280 kg/m2) 7 (480/336 kg/m2) 8 (560/392 kg/m2)
Wind load calculation:
Ia I II III IV V VI VII
Height to the ridge of the building
5 m from 5 m to 10 m from 10 m
Terrain type
Open area Closed area Urban areas
Roof angle: 0 degrees.
The tilt angle is suitable for of this material.
It is advisable to increase the angle of inclination for this material!
It is advisable to reduce the angle of inclination for this material!
Roof surface area: 0 m2.
Approximate weight roofing material: 0 kg.
Number of rolls insulating material with 10% overlap (1x15 m): 0 rolls.
Rafters:
Load on the rafter system: 0 kg/m2.
Rafter length: 0 cm
Number of rafters: 0 pcs.
Lathing:
Number of rows of sheathing (for the entire roof): 0 rows.
Uniform distance between sheathing boards: 0 cm
Number of sheathing boards with a standard length of 6 meters: 0 pcs.
Volume of sheathing boards: 0 m3.
Approximate weight of sheathing boards: 0 kg.
An online calculator for a gable (gable) roof will help you calculate the angle of the slope, the size and number of rafters, the amount of sheathing, and the volume necessary materials in online mode. The calculation base includes in advance such common roofing materials as metal tiles, slate, ondulin, tiles made of ceramics, bitumen, cement and other materials.
Note! Calculations are made based on SNiP “Loads and Impacts” and TKP 45-5.05-146-2009, taking into account the standards contained in these documents.
Gable roof (also spelled “gable roof”, “ gable roof") - a roof option with two slopes running from the ridge to the outer walls of the building. Today this is the most common type of roof, due to its ease of execution, low cost and attractive appearance.
The rafters in the construction of such a roof rest on each other in pairs and are connected by sheathing. The end sides of a structure with such a roof have the shape of a triangle and are called pediments (sometimes - gables). Usually, an attic is installed under a gable roof, and small attic windows are made on the gables for lighting.
When filling out the fields of the calculator, pay attention to the “Additional information” icon, which hides explanations for each item.
The calculation results are also accompanied by explanations, which you can read below.
This is the name of the angle at which the slope and rafters are inclined to the plane of the ceiling. The calculations were made taking into account the fact that it is planned to build a symmetrical gable roof. By entering an angle, you can not only calculate required quantity materials for a given angle, but also check whether it is possible to build a roof at this angle from the materials you have chosen. You can decrease or increase the angle by changing the width of the base or the height of the rise: these parameters are strictly interconnected.
The total area of the roof slopes, including the area of overhangs of a given length. Determines the amount of roofing and under-roofing material required during roof construction.
Estimated total weight of roofing material.
The required amount of under-roofing material, taking into account the required overlap of 10%. In our calculations, we assume rolls 15 meters long and 1 meter wide.
The maximum possible load, taking into account wind and snow loads, on the rafters.
Rafters are measured from the base of the slope to the ridge of the roof.
The total number of rafters required for a roof truss system at a given pitch.
To ensure the roof has sufficient strength, it is necessary to select rafters with the section options suggested here.
With the parameters you specify, this number of rows of sheathing will be required. If you need to determine the number of rows for one slope, then this value must be divided by 2.
To eliminate waste of materials and save yourself from unnecessary trimming work, you need to choose a given distance between the sheathing boards.
The number of boards required to sheath the entire roof (in cubic meters).
For low-rise buildings, a truss roof is ideal. It will decorate the facade of the house, and with a sufficient slope, snow will not accumulate on such a roof, unlike a flat structure.
One of the varieties rafter roof – gable. This is enough simple system, which is formed by two slopes. The roof slope is the entire inclined plane through which drainage is provided.
The structure rests on two parallel walls. This roof forms two triangular side gables. The pediment is the completion of the facade of the building.
There are four main types of gable roofs:
The choice of the type of gable roof depends on the purpose of the room located directly below it and the architectural appearance of the building.
The most important load-bearing parts of the rafter system gable roof The buildings are mauerlat, transom and rafters. The Mauerlat works in compression, so its cross-section can be taken conditionally.
The crossbar and rafter legs experience a bending moment.
Such structures are calculated based on strength and rigidity. For small buildings, you can choose their cross-section approximately, but for serious buildings, for the sake of safety and saving material, the calculation of the rafter system should be performed by a professional.
To perform the calculation you need to know the load per 1 square meter. roofs.
To do this, you need to add up masses of 1 square meter. all roofing materials:
The snow load is different for each area and is equal to the weight of the snow cover on a horizontal plane.
On the territory of Russia it can receive values from 80 to 560 kilograms per square meter. On the Internet you can easily find a snow load distribution map and select the desired number based on the construction area.
The angle of inclination of the roof is quite easy to calculate if you know the geometry and have an engineering calculator or a standard calculator on your personal computer at hand.
If you divide the height of the roof by the distance from the ridge to the eaves in plan, you get the slope of the roof in fractions or the tangent of the angle of inclination. In order to calculate the angle, you just need to find the arctangent.
If using an engineering calculator is difficult, the arctangent can be found using an online calculator.
Rafter pitch mansard roof should be chosen for ease of installation of insulation. Mats usually have a width of 60 centimeters, so the pitch of the rafters should be chosen so that the clear distance between them is 58 or 118 centimeters. Two centimeters will allow you to install the insulation boards very tightly, which will allow it to stay between the rafters and improve thermal insulation.
Leg length can be easily calculated using the formula:
L/cosα,
here L is the distance from the roof ridge to inner surface outer wall in plan, and cosα is the cosine of the roof inclination angle. For rigid fastening, you need to increase the size of the notch.
The cross-section of the rafter leg must be selected as a multiple of the size of the boards and beams.
An example of a simple calculation of the cross-section of a rafter leg:
To solve, you need to set the width and find the height by solving a simple quadratic equation. The width can be set to 5 cm, 7.5 cm, 10 cm, 15 cm. For small spans, a width of 15 cm is not practical.
To calculate rafter systems, there are all kinds of tables, programs, online calculators.
The main elements of a gable roof, like any other rafter roof, are:
To fully utilize the space under the roof, you can design an attic.
Attic floor- this is the floor in attic space. The attic façade is formed entirely or partially by the roof surfaces. According to regulatory documents In order for a room to be considered an attic, the line of intersection of the roof plane and the outer wall should not be higher than 1.5 m from the floor level. If this requirement is not met, the space will be considered a regular floor.
Roof attic floor differs from attic roofing in the presence of insulation in its design. Most often for insulation mansard roof mineral wool boards are used.
Lighting the attic space can be done in three ways:
Dormer window – This window design, which has a frame mounted simultaneously with the rafter system. This frame is made of wood. The dormer window has its own small roof, which can be gable or cylindrical. The glass unit itself is installed vertically.
Dormer window - This is a window specifically designed for use on rafter roofs. It is installed in the plane of the slope in an inclined position. The roof window must withstand the calculated snow load. It is better not to use this type of window in roofs with a slight slope.
Once the appearance of the roof has been determined, you can begin to select the material. There are several types of modern coatings. In the list below, material options are listed in descending order of average market cost.
The roofing material completely depends on the wishes and capabilities of the customer. The exception is roofs with too large or too small a slope, since all materials have limitations on the angle of inclination of the slope.
Structural roof truss systems can be of three types:
Installation occurs in the following order:
Attaching the rafter leg to the mauerlat can be rigid and hinged.
Makes it possible to compensate for the expansion of wood under the influence of humidity and temperature changes.
Fastening can be done in several ways:
The rafter is attached to the mauerlat with a notch and is securely fixed with nails driven at an angle relative to each other. One nail is driven vertically onto the surface of the Mauerlat. This connection eliminates displacement in any plane.
The gable rafter system has undeniable advantages. You can design and install it yourself, you just need to take this issue responsibly and think through everything down to the smallest detail.
The online gable roof calculator will help you calculate the angles 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 roof from such popular roofing materials as slate, ondulin, ceramic, cement-sand and bitumen tiles, 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.
The rafters in a gable roof structure rest 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 of roofing material required for full coverage roof area.
The total amount of insulating material in rolls that will be required to insulate the roof. 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 lathing.
Estimated total weight of sheathing boards. The calculations use average values of density and moisture content for coniferous wood.
