Calculation of the roof of the house: program. The formula for calculating the roof of the house

If you decide to redesign the roof of your private house, or build it from scratch and it comes to its construction, you have two options: either to resort to the services of professionals, or to do it yourself. In the second case, almost every homeowner is faced with the problem of how to calculate the roof of the house so that it does not form a card house from the slightest gust of wind. It will allow you not only to calculate the required strength of the structure, but also to find out the necessary amount of material for its implementation. Below we will consider in detail all the stages of designing such an important element as the roof of the house with our own hands. The calculation should be extremely accurate.

Initial data

To perform a correct calculation, you will need additional information about the dimensions of the house and the dimensions of some of its elements. To make calculations for the roof in the manner described below, you will need information about the approximate weight of the entire structure, including the material that will cover its frame. Also important is the size of the cross-section of the beams on which the roof will hold. Calculating the size of a house can somewhat simplify the task if the roof has no more than 2 ramps.

Roofing system

The roof frame is a rafter system consisting of a set of wooden beams. Such systems can be very diverse, and their design depends primarily on the type of roof that you are going to build.

Typically, the type of roof is determined by the number of skates on it, which can vary from one to four. To calculate the necessary amount of building materials, you need to correctly calculate the strength of the structure, and, consequently, the most optimal length and thickness of the bars. This information, in turn, depends on the number of supposed skates of the future roof.

The calculation of the required amount of wood material begins with the definition of the tree species from which the timber will be made. Depending on the initial data, the calculation is performed in such ways:

• At a known value of the cross-section of the bars, the method of their installation is calculated;
• With the already defined way of laying the beams, the necessary size of their sections is calculated.

Load calculation

In order to calculate the distance from each other it is necessary to lay the uneven bars (the laying step), it is necessary to calculate the load on the roof itself. The total load consists of all individual loads. These include the main, that is, the weight of the cover and the weight of the roof, and secondary: the snow cover in the winter, the wind load, the weight of people who from time to time will repair or maintain the roof, directly on it. It is also highly recommended to provide sufficient safety factor for the construction in case of extreme situations like hurricanes.

Calculation of the roofs of private houses - the number of rafters

Calculating the total load, you can begin to calculate the required number of rafters to ensure the optimum strength of the frame foundation of the roof. Remember that it is also necessary to take into account the angle at which these rafters will be built.

To determine the maximum permissible load, which will act on one running meter of the bar, use specialized directories containing special tables. To ensure sufficient strength with a small margin, calculate the total footage. Further, knowing this indicator, as well as the length of one rafters, calculate the required number of beams. Finally break their total number in pairs and distribute them along the entire length of the roof structure.

That's how the calculation of the roof of the house is done. A program that automatically calculates loads on structures of this kind can significantly improve the accuracy of your calculations. Finding such a program is not a problem, there are enough of them on the network, and their use is free. Enter in it the initial data such as the type of roofing material, the type of timber beams, the length and width of the base, the height of the roof, the length of the overhang and the rafter step, and at the exit you will get a lot of useful information, such as the total surface area of the roof, the approximate weight of the rafters and Roof, required length, section and number of rafters.

The formula for calculating the roof of the house: an example

Suppose that you have already calculated the length, height and other necessary parameters of the future design. Let's say the roof slope is 45 degrees, and the length is 6 meters. The length of the rafters is 4 meters and the maximum load per running meter of the beam is 100 kg. Calculations of the total load, including wind and snow, led us to the figure of 2000 kg.

In order to calculate the optimal distance, on which the rafters must be located from each other and withstand a load of not more than 100 kg per running meter, divide the total load by the load per running meter. As a result, you will get an allowable minimum of the total length of the rafters. Those. 2000 is divided by 100 and we get 20 meters.

Calculate the required number of rafters now will not be difficult, for this, divide the total length by the length of one bar. 20 divide by 4, we get 5 pieces. But this is not all - because the bars are set in pairs, 5 need to be divided into two and rounded up to an integer in a larger side, if this is necessary. In our case, it will be 3 pairs. Keep in mind that this is not yet the final number.

Finally, to obtain the desired maximum allowable step, divide the total length of the roof by the number of pairs of rafters minus one pair that will be located at the edge. That is, 6 divide by (3 - 1), we get 3 meters. Take into account that 3 meters is the maximum permissible distance between the rafters, and for greater reliability it is recommended to place them closer to each other, for example, every 2 meters.

With a step between rafters of 2 meters try again to calculate the necessary number of rafter pairs. To do this, we divide the total length of the roof by 6 m per step in 2 m, and we get 3 pairs. Do not forget to take into account the pair that will be on the edge of the roof, in total we need 4 pairs of four-meter rafters.

Calculation of the material for the roofing

First you need to calculate the surface area of the roof correctly. As in the case with rafters to perform the calculation of the roof of the house - the program for calculating the area of such complex surfaces is the best solution that will allow you to avoid many mistakes and errors. These programs include 3D Max and Arcon. If you are a confident PC user, it will not be difficult to understand them. If you are far from 3D modeling, you can use more simple online services.

Suppose you decide to cover your roof with tiles. For this material, two types of width are characteristic - real and effective. From the name you can understand that the real width of the sheet is its actual dimensions. The effective is due to the width of the roof surface, which is covered with a sheet of metal tiles, taking into account overlapping of adjacent sheets on it. Actually, this is the reason why the effective width is always less than the real one. Let's assume that the actual width of the sheet of material is 1180 mm. Then its effective width will be approximately 1100 mm.

After understanding the width, you can begin to calculate the length of the roof. It can be measured by the roof roof or by its skate. Calculate the number of sheets of material necessary to lay one row from edge to edge of the roof. Divide the length of the roof by the effective width of one sheet and, if necessary, round the result towards a larger whole number. Suppose that the length of the roof is 7 meters. Then the number of sheets will be 7 / 1,1 or 7 sheets.

Next, we'll do the same operation, but now about the width of the roof, that is, the distance from the eaves to the roof ridge. It is important to take into account such additional parameters as the eaves length and the width covered by the adjacent sheet (as a rule, it is equal to 150 mm).

Let the width of the roof be 4 m, the cornice overhang is 30 cm, and the sheet length is 1 m. The effective length of the sheet is 1 m - 15 cm = 85 cm. The total width to be covered is 4 m + 30 cm = 4.3 m. To obtain the required number of sheets, divide a total width of 4.3 m into an effective sheet length of 0.85 m, and get 5.05. Since ridge tiles partially cover the roof area, the resulting number can be rounded to 5 sheets. Finally, we obtain a total number of them to cover the entire surface: 5 * 7 = 35 sheets. Thus, the calculation of the roof of the house is carried out. The program (4 pitched roof construction is very difficult for manual calculations) will make the majority of computing operations for you.

Calculation of insulating material

Since the insulation material is usually sold by rolls, to calculate its amount, the roof area should be divided by the area of the material in one roll. Take the simplest case of a gable roof with a length of 7 m and a width of one ramp of 4 m. We calculate the area of one ramp, multiplying the length and width by 28 m ² . The total area of the roof is 56 m ² . Suppose that 80 m ^{2 of} material are wrapped in one roll. Approximately 10 m ² of them will go to the floors. But even in this case it is already clear that one roll is enough for work.

In cases with more complex forms, use online calculators to calculate the roof of the house. The program will greatly facilitate your work.

Calculation of cost

To calculate the approximate value of the material, you must multiply the price for its unit by its required quantity. It is recommended to increase the received cost by 10%. You should also take into account the various spare materials, the cost of transportation and other services that you are going to use.

Conclusion

Finally, I would like to remind you that before you start any work, spend more time calculating the roof of the house - a program that is able to perform calculations in complex forms, will greatly facilitate your life and save money.