When drawing up an estimate for the construction or renovation of a house, one of the most important tasks is the correct calculation of the roof area. This article will talk about how to calculate the roof area, what characteristics are taken into account and how the calculation is made for different roofing materials.
Most often, developers are faced with the following questions when calculating the area of \u200b\u200bthe roof - how to calculate the area correctly, taking into account the very shape of the roof, as well as a large number of complex elements, such as attics.
To calculate the area most correctly, perform the following steps:
- Do not subtract additional elements from the total area (chimney pipes, ventilation holes, dormers and roof windows, etc.);
- Know exactly how to calculate the roof slope from the bottom of the ridge to the edge of the eaves;
- Firewall walls, overhangs, parapets, etc. are calculated;
- Consider for which material the area is calculated.
Important: when calculating the roof area, it should be noted that rolled roofing materials and tiles reduce the length of the slopes by 70 cm.
Before calculating the roof area, it is desirable to break it down into its constituent elements in the form of geometric shapes (trapezoids, triangles, etc.), for each of which a separate calculation is made, after which the total area is obtained by adding the obtained values.
After the areas of individual slopes have been calculated, it is necessary to find out what slope the roof has relative to the ground by multiplying each individual element by the cosine of its angle of inclination.
If there is a fairly simple roof area - how to calculate it (for example, a gable roof, the slope of which is 30 °)? The task is further simplified, it is enough to multiply the area of \u200b\u200bthe slope by the cosine of the angle.
In the case of more complex roofs, it is recommended to use special calculator programs that reduce the risk of errors that lead to problems during operation.
Factors Considered in the Roof Area Calculation Process
When thinking about how to calculate the area of \u200b\u200bthe roof, you should first take into account the type of this roof itself.
So, for a combined type of roofs, which is most often used in the construction of outbuildings, the calculation of the area usually comes down to multiplying the length of the building by its width.
In the case of residential buildings, attic and attic types of roofs are usually used. These types require more complex calculations due to differences in configuration - flat, multi-gable, gable, four-slope, hip, etc.
The calculation of the roof area in this case begins with the calculation of the angle of its inclination (11-70 ° depending on the climate of the area).
Calculation of the total roof area
In order to calculate the area of a roof before buying material to cover it, a fairly large number of different factors should be taken into account, for example, the key features of different types of roof structures.
However, many options require the calculation of the amount of material in pieces or sheets instead of square meters.
In order to calculate the amount roof material in pieces, it is necessary to have accurate data on the height of the roof and its slope.
To perform the calculation, a simple formula is used. In the case of a soft or galvanized roof, a completely different formula is used:
S = (2 x a + b) x (2 x a + c) / cos (m),
Where S is the roof area, a is the width of the overhangs, b and c are the length and width of the house, m is the angle of inclination. All indicators used should be taken on slopes.
You should also consider in more detail the various options for calculating the roof area, depending on the type of coverage.
- slate roof. The number of sheets required to cover the roof is calculated using simple mathematical formulas, this requires data such as the length and width of the house, as well as the width of the roof eaves.
- The calculation formula is as follows: Roof area = (2 x eaves width + house length) x (2 x eaves width + house width) / cos (slope angle).
- Example: if the dimensions of the house are 10x15 m, the angle of inclination is 30 °, and the width of the overhang is 0.5 m, then the area will be equal to (2x0.5 + 15) x (2x0.5 + 10) / cos (30) = 16 x 11 / 0.87 = 202.2 m2.
- The calculation of the area of the metal-tiled roofing also has its own characteristics. You need to know the following quantities: the sum of the lengths of ridges, overhangs and valleys, cornices, the length and width of the building, as well as the number of ridges and their total length. In addition, when calculating the area of \u200b\u200bthe roof, the number of slopes and their type should be taken into account.
- When covering a roof with flexible soft materials, the following roof calculation formula is applied: Roof area = (2 x eaves width + house length) x (2 x eaves width + house width) / cos (angle of inclination). It should be taken into account that the coverage area ridge roof and valleys are calculated separately, and the amount of material used also depends on what type of tile is used. When calculating soft roofs, the following principles are used:
- All elements of the roof structure should be taken into account;
- Sometimes it is required to carry out an additional calculation of the height of the roof and the calculation of the rafter system;
- It is also important to take into account the overhangs of the cornices, the overlap of the ridges and the size of the overlap.
Example: if the dimensions of the house are 5x10 m, the angle of inclination is 45 °, and the width of the overhang is 0.5 m, then the area will be equal to (2x0.5 + 10) x (2x0.5 + 5) / cos(45) = 11 x 6 / 0.70 = 94.2 m2.
- In recent years, the use of environmentally friendly materials for the construction of roofs has become increasingly popular.Such materials include materials made of wood, such as shingles, gon or shipdel, which are varieties of tiles made of wood 40x (9-10) cm in size. When calculating the roof area for such material, it is important to consider that the wooden tiles are laid in 3 layers, and for 1 m2 surface takes up to 80 coating elements. To calculate the area, standard mathematical formulas for the areas of figures are used.
- The roof area for covering with corrugated board is recommended to be calculated by qualified specialists. If it is necessary to independently perform calculations, it is important to take into account the number and type of roof slopes. In the case of a simple gable roof, the area is calculated by multiplying the length by the width. Since the width is determined by the ridge, the resulting value is multiplied by two. In the case of more complex roofs, the areas of each slope are calculated separately. The calculation of the required amount of material is carried out in accordance with the dimensions and characteristics of corrugated sheets. This takes into account the following factors:
- The dimensions of the roof elements, taking into account the holes;
- overlap areas;
- Overhangs and ceilings of skates.
- Hip roofs are a type of pitched roofs and are made in the form of a tent or tent. At the same time, the area of \u200b\u200bthe roof can be calculated by finding out what values \u200b\u200bthe small areas of individual elements have, of which there are only four: two hips in the form of triangles and two in the form of trapezoids. Calculations of the areas of hip roofs are one of the most complex, therefore, special calculator programs are usually used to perform them.
Important: without performing the necessary calculations, in no case should you start cutting the elements of the roofing.
How to perform an area calculation
In order to start calculating the roof area, you will need the following materials and tools:
- Detailed roof project;
- Calculator;
- Roulette;
- It is also desirable to have a special program for the calculation.
Before you begin to perform the calculation, you should decide what material will be used to cover the roof. Next, you should divide the entire covered area into conditional triangles that simplify the calculations.
With the help of a tape measure, all the necessary parameters are measured. When calculating areas, the slope coefficients can be determined using the following formulas and values:
- for a slope of 9 ° (2-12 or 1:6) - a coefficient of 1.01;
- for 14° (3-12 or 1:4) - 1.03;
- for 18° (4-12 or 1:3) - 1.05;
- for 23° (5-12 or 1:2.4) - 1.08;
- for 27° (6-12 or 1:2) - 1.12;
- for 34° (8-12 or 1:1.5) - 1.2;
- for 40° (10-12 or 1:1.2) - 1.3;
- for 45° (12-12 or 1:1) - 1.41;
- for 49° (14-12 or 1:0.86) - 1.54;
- for 53° (16-12 or 1:0.75) - 1.67;
- for 56° (18-12 or 1:0.67) - 1.8.
In the case of a complex roof, on which elements such as ledges, ridges, skylights, etc. are present in large numbers, the geometrical projection of the roof is drawn up as accurately as possible. All measurements are made either directly on the roof surface, or from the ground, or from the attic.
Before calculating the roof area, it is divided into separate geometric shapes, the areas of which are calculated separately.
When making calculations, it is important to remember that different coefficients are used to calculate areas for different slopes.
Useful: after performing the calculations, it is recommended to add 10% to the resulting total roof area in order to cover the errors that could be made in the calculations.
As can be seen from this article, when building a roof, it is quite possible to calculate the roof area of \u200b\u200ba house on your own, the main thing is to carefully check all the indicators.
It is also desirable to use special programs for calculating the area, which minimizes the risk of possible errors in the calculation.
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