You need to know the exact areas of the roof slopes not only in order to correctly calculate the amount of material to purchase, but also the amount of work for which you will have to pay when hiring a team. The dimensions of the roof, as well as the volume of work performed on it, are always calculated in square meters. The only difference is that when purchasing material, some corrections and coefficients are taken into account.
Table 1. Nuances when calculating coverage.
| Nuances in the photo | What to take into account: instructions |
|---|---|
| Whatever material you buy, when calculating it, you should always take into account the full area of the roof according to the existing project (or your calculations). Important! At the same time, it is impossible to subtract from it the areas occupied by superstructures: a chimney, a dormer or attic window, a mezzanine. And even vice versa, if they need to be lined with the same material, you should calculate how much it will take and add it to the total amount. |
| When measuring the parameters of the slope, you must remember that this is the size not between the ridge and the support point on the wall, but between the ridge and the outermost line, taking into account the overhang. |
| When calculating the material, the location of the gutter also matters. If it is not on the wall, but on the cornice, then 7 cm is added to the area of the slope. |
| The area of the walls of existing parapets on the roof, which require covering with the same material, is calculated separately. |
| When covering roofs with galvanized steel sheets, bypasses chimneys usually performed by installing folds that extend onto vertical surfaces. They do not need to be taken into account when measuring slope areas. |
| Sections of the roof in those places where it is adjacent to vertical structures do not need to be taken into account separately. |
Please note and like this, very important nuance. When the roof has an overly complex configuration, which complicates the measurement process, the area can be calculated not from the slopes themselves, but from their projection, using correction factors. But for this you need to know the exact parameters of the slope.
Table 2. Slope parameters.
| Slope degree | Correction factor |
|---|---|
| 7 | 1,014 |
| 8 | 1,02 |
| 10 | 1,031 |
| 13 | 1,054 |
| 15 | 1,077 |
| 18 | 1,118 |
| 22 | 1,202 |
| 30 | 1,41 |
Just a note. If the roof has several sections lying at different horizons, but not interconnected by the roofing material, the area of each of them is calculated separately.
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Calculation of areas in the traditional way
Now that general requirements and the amendments have been agreed upon, you can proceed directly to the calculations. Actually, they come down to determining the area of one or another geometric figure, which is what any slope represents. Many people can remember the principles of calculations from a school geometry course; you just need to use a tape measure and a calculator correctly.
Pyramid and arched elements roofs
Depending on the roof configuration, you will most often be dealing with a rectangle or parallelogram, triangles or trapezoid. Quadrangles of irregular shape can always be divided into a regular rectangle and one or two triangles, and calculated each separately. For those who are good at mathematics, it may be easier to use the formulas presented in the picture below.
Before you begin direct calculations, you should already have ready plan and sections of the roof indicating horizontal and vertical dimensions. Those who have construction documentation are lucky, and if they don’t have it, they will have to climb onto the roof with an assistant, armed with a notepad, pencil and tape measure.
Let's figure out in what case and what exactly needs to be measured, and how to make calculations.
Roof with one slope - or two identical ones
If you were able to measure the full length of the slope, which, as already mentioned, is the distance from the ridge to the edge of the overhang, then multiplying the result by the width, you will get the area. Alternatively, to determine the length of the slope, you can use the projection method, for which you need to know two of the three dimensions of the triangle formed by the slope. The formulas are presented below.
When calculating the length of the slope according to the projection, do not forget to add the length of the overhang to the total. Using the same principle, you can calculate a gable roof. If its slopes are the same, it is enough to calculate the area of one and double the result.
Hip and hip roofs
The peculiarity is that there are no rectangular slopes, but triangles and trapezoids. In hipped roofs there are only triangles, since there is no ridge in such roofs, and the slanted rafters are connected at one central point. Therefore, the principle of calculating areas is one and gable structures not applicable here.
Your task is to calculate the area of each slope, differing in configuration, separately, using the appropriate formulas. For triangles they are the same, but for trapezoids they are different - and there can be several methods of calculation.
If the house is square in plan, then with a hip roof all four slopes will be equal. If such a roof is made over a rotunda (a building with spherical walls), there can be 6 slopes with the same proportions. Therefore, having calculated the area of one, multiply the total by 4 or 6.
You can determine the area of the trapezoidal slope in three ways as shown in the photo below.
Roofs, most often mansard, can also have a half-hip design. They differ from hip ones in that, due to very small side triangles, large slopes do not have a trapezoidal shape, but an irregular hexagon configuration. Its area is calculated by dividing it into two figures: a rectangle and a trapezoid. In the picture this division is shown with a red line.
Calculate the area of each figure separately and then add it up.
Roofs with spherical configurations
The most aesthetically pleasing from an architectural point of view are combined ones, in which there are elements of different shapes. As a result, they make up a coating of a rather complex configuration, each section of which must be calculated separately. Including, on the roof there can be not only planes, but also spherical surfaces: a cone or hemisphere, which are usually designed over rounded walls or extensions in the form of towers.
In any case, the calculation of their area is also determined using mathematical formulas.
Calculate the area of the roof, floor, volume of concrete for the foundation and take into account other details of the house design when low-rise construction you can do it yourself, without using complex architectural design programs.
The desire to rationally use the space under the roof and the desire to emphasize individuality lead to the appearance of roofs of complex shapes.
Construction technologies provide architects and designers with ample opportunities to implement projects of any complexity. They allow you to design houses in any style while maintaining the optimal price-quality ratio. The desire to rationally use the space under the roof and the desire to emphasize individuality lead to the appearance of roofs of complex shapes. If previously domes, spiers, turrets and mezzanines were a feature of large architectural projects, now such architectural details can be found on country houses and cottages. Sometimes the design of a roof can be more complex than the house itself.
The covering of each house performs two main functions: protective and aesthetic. The roof protects the building from precipitation and is pleasing to the eye.
The choice of roof slope depends on the snow load in the region. The smaller it is, the stronger the coating should be. Accordingly, the cost increases. But an increase in the angle of inclination increases the roof area and its cost.
The variety of roof designs can be reduced to several main types. They are:
- single-pitched;
- gable;
- hipped;
- roofs of complex configuration with numerous slopes.
Four slopes, in turn, can be divided as follows:
- hip;
- half-hip;
- tent
If a building is being built according to a project made in any architectural design program, calculating the roof area will not be difficult. But the fact is that the design and actual dimensions of the structure can vary, sometimes quite significantly.
When determining the actual dimensions, it is important to take correct measurements. If truss structure If the roof is ready and the roof area is calculated to determine the need for roofing materials, then the inclined part can be measured along the rafter leg. When measuring, you need to take into account the eaves overhang. It can be lateral or frontal. Side overhang is structural element, protecting the walls of the building from precipitation. As a rule, it is 50-100 cm, but not less than 50 cm. The front overhang protects the gables of the building.
In low-rise construction, houses are often built without a design at all. Sometimes the decision about what type of roof will be made with the walls ready.
Moreover, choosing the angle of the roof is also a matter of aesthetics. If you plan to build an attic, then the angle of the roof is selected based on considerations of a comfortable height. For the attic it is 150 cm.
In this case, the quadrature can be calculated using the actual dimensions of the walls. The length of the sloping part of the roof can be determined by the angle of the roof.
Calculating the square footage of even the most complex roof configuration can be reduced to simple arithmetic operations.
Shed roof
If we designate the length of the building as A, the width as B and the overhang as C, then the quadrature S can be easily calculated using a simple formula: S= (A+2C) × (B+2C).
But a flat roof is more in demand in the southern regions. In conditions middle zone Russia, and especially in Siberia and the Far East, a flat roof requires complex engineering solutions on the design of drains and reinforcement from snow loads. To avoid this, the coatings are made with a slope. The area of the sloping roof increases. If the slope goes along side B, the inclined side is designated D, then its length can be calculated using the formula: D=B/cos α, where α is the angle of inclination. In this case, the formula for calculating the area of a sloping roof will look like this: S= (A+2C) × (B/cos α+2C).
A single-pitch roof is not difficult to calculate and install, but is more often used in the construction of outbuildings.
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Gable roof
The gable roof is most often used in low-rise construction during the construction one-story houses. Its installation is simple. In addition, its convenience lies in the resulting two gables, which provide access to the attic of the house.
To simplify the calculation, two pitched roof at home you need to imagine it as a combination of 2 lean-tos. A gable roof necessarily has an angle of inclination, and it is not always the same.
Let's denote the slopes S1 and S2.
Let us denote the angle for the slope S1 as α, for S2 as β.
We denote the projection of the inclined side of the slope S1 as B.
We denote the projection of the inclined side of the slope S2 by F.
In this case, the formula for calculating a gable roof S will look like this:
- S1= (A+2C) × (B/cos α+ C).
- S2= (A+2C) × (F/COS β+ C).
- S= S1+S2.
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Hip roof
A hip roof is somewhat similar to a gable roof. It has no pediments. 2 of its sides are in the form of a trapezoid, and 2 of its sides are in the form of a triangle. There are also half-hip roofs, which have 4 sides in the form of a trapezoid and two small gables. Calculation of a rather complex figure of a hip model comes down to determining the components that are simple in shape. These are a trapezoid and a triangle.
The area of the triangle is: S= (b × h)/2, where b is the base, h is the height.
The area of the trapezoid is: S= (a + b)/2 × h, where a and b are the upper and lower bases, h is the height.
If the hip roof is symmetrical, then the formula by which you can calculate its area will look like this.
The area of the triangular component is S1, the area of the trapezoidal component is S2.
Let's denote the lower bases as A and B.
To simplify, let’s immediately add the length of the overhangs to their dimensions.
The ridge part, or the upper base of the trapezoid, will be denoted by F.
We denote the projection h1 for the triangular component by E.
We denote the projection h2 for the trapezoidal component by K.
Let us denote the inclination angle of the triangular component as α, and for the trapezoidal component as β.
For the trapezoidal component: h2= K × cos β.
The total area of the triangular part will be: S1= ((A × h1)/2) × 2.
The total area of the trapezoidal part will be: S2 = ((B+F)/2×h2) × 2.
The total figure (Stotal) will be equal to: Stotal. = S1+ S2.
It can be seen that calculating the quadrature of a hip roof is not very difficult.
When carrying out any construction work, including roofing, requires an accurate calculation of the material, both main and auxiliary. Thanks to a thoughtful approach to defining required quantity finishing coating roofing, as well as components and consumables(insulation, waterproofing, lathing, fasteners) you provide yourself with several advantages at once:
- You buy everything at once in one place, guaranteeing a complete color match of the material. The need to purchase additional material from another place, from another batch, can lead to the difference in shades being clearly visible on the finished roof. Why do you need this?
- An accurate calculation of the roof will help avoid the need to subsequently purchase additional material, and this requires time, effort, additional expenses(there is a difference between bringing everything you need in one car or hiring special transport several times).
- Roofing calculations from specialists are a guarantee of the absence of a large amount of unnecessary surplus. Then you also need to do something with them (sell them, remove them from the site), and this is also a waste of time and money.
Before starting roof construction, it is necessary to calculate the material. There is an online calculator specifically for this on our website. Its main purpose is to help the buyer estimate the approximate cost roofing material. Knowing the amount of metal tiles, corrugated sheets, flexible tiles, which will need to be purchased to cover the roof, you can calculate the approximate cost of the roof (excluding discounts and possible bonuses).
Also, the roof calculation calculator will allow you to calculate the approximate cost of the roofing work itself, since knowing the amount of material you can calculate this value. Knowing these numbers, you will be able to fully prepare for such an important and responsible event as purchasing material and concluding a contract for roofing work.
Calculation results
Above the roof layout there are switches for product profiles; they will allow you to select the required profile, taking into account its working width and restricted lengths. To view the layout of sheets on a ramp, select the ramp by clicking on it. Use the arrows to change the length of the sheets according to your needs for the selected slope.Calculation results
Below are the parameters of your roof and the amount of material required, taking into account the prohibited lengths and overlaps of the sheets. You can then add the item to your cart and, if necessary, cancel any items in your cart.How does the online roof calculator work?
The first determining factor when calculating a roof is its shape. When filling out the fields online calculator and you can choose the type you need, this step will be the very first. You will be able to calculate single-pitch, gable, four-pitch hip, mansard roof etc.
Also included in the online roofing cost calculation are other parameters that affect the amount of material - the need for insulation, additional elements (overhangs, gutters, etc.). The greatest attention, of course, should be paid to the size of the roof. In order to get the most accurate calculation possible, when specifying dimensions, check the drawing.
As a result, the online house roof calculator will give you all the necessary numbers, taking into account the choice of the type of metal tile profile and the cost of all the necessary materials at the Roofing No. 1 company. The program will calculate the total roof area, the cost of the finishing coating, additional elements, fasteners, as well as the cost additional elements, if you indicate this when filling out the form (insulation, waterproofing, drainage system, soffits). Also, the roofing cost calculator will calculate the amount for installation work"turnkey". The total amount will reflect all your expenses, both for the purchase of materials and for the installation process.
How to buy materials after roofing calculations?
You can order and buy everything you need for roofing installation right here, without leaving the calculator page. The order will be automatically generated in the shopping cart, you will be able to make all the changes you need, refuse some goods or services and calculate the final cost. You can pay for your purchase directly through the website using bank card, non-cash transfer. Cash payment is made at the company office.
This is very convenient, allows you to save your time and money, and also purchase everything you need for the roof in one place, without tedious trips in search of the necessary materials.
This online calculator allows you to get a fairly accurate preliminary calculation, which is especially suitable for those who are planning to build a roof of a simple shape. If you have a project for a complex, multi-slope roof with skylights, to calculate the cost, it is best to contact the specialists of the Roofing No. 1 company.
During construction, people face a lot of different problems. One of them is arranging the roof and calculating the amount of material required for its construction. You can find out only if you correctly calculate the area that needs to be covered.
Peculiarities
It will not be possible to calculate the roof area using some universal formulas. For a simple pitched roof, such calculations are the simplest, but there are always nuances, ignoring which leads to dire consequences.
Calculating area always involves:
- accurate height measurement;
- determining the degree of inclination;
- determining the volume of required building materials and fasteners for them (as the final stage).
Design forms
The area of a pitched roof is calculated depending on what geometric figure the proposed roof corresponds to - most often these are isosceles triangles, trapezoids, rectangles and parallelograms. But it is important to consider that almost all roofs still consist of several slopes.
The lean-to option is calculated using the formula for a rectangle.
If there are two slopes, you just need to apply the same formula to each of them and summarize the results.
A roof of four slopes is calculated as the sum of a pair of trapezoids and a pair of triangles with equal sides.
If the form is very complex, you will need to spend more time, but the basic principles remain roughly the same. The first step is to break it down into simple geometric shapes. Then the same formulas are used to calculate the area of any of them as in the standard case. We must not forget that the length of the slopes is measured from the final lines of the eaves to the ridge elements.
When the area is of irregular shape, it is advisable to divide it into even smaller fragments in order to radically simplify the calculations.
Do not subtract chimneys and ventilation ducts , windows built into the roof and other similar elements. When calculating the area of a flat roof for laying built-up roll materials The area of parapets is taken into account separately. It is necessary to take into account how the overhang will be located - along the perimeter, with a closed parapet or with a lower overhang and a three-sided parapet.
In the very in simple form square flat roof can be taken equal to the total area of the building, with the addition of overhangs and other elements extending beyond the contour. But such a calculation scheme is acceptable only if there are actually no angles.
With due diligence, it will not be difficult to calculate the area of the pediment yourself. To do this, there will be no need to even turn to online calculators. The configuration of the pediments is closely related to the geometry of the slopes: thus, triangular options most often accompany the formation of roofs with two slopes. When installing the structure, before preparing the rafter frames, the area and height of the gables must be calculated with special care.
Produce necessary calculations, as always, using “school” formulas helps. It is advisable to use electronic calculators only for self-testing.
The lengths of the end walls, divided in half, are multiplied with the tangent of the angle, which creates the slope and base of the roof. For a non-residential space under the roof, the height will be much lower than for one actively used by people. A triangular wall is calculated by multiplying the height of the pediment itself and the length of the roof base. This result should be reduced by 50%. In the case of a “trapezoid” wall, take ½ of the total length of the bases and multiply it by the height. The pentagonal pediment is conventionally divided into an upper triangle and a lower trapezoid - this simplifies the calculation.
Calculating the area of an L-shaped roof with different slopes is also not particularly difficult. By its nature, it is formed from a pair of standard gable structures joined at right angles. To simplify calculations, the general configuration is divided into four similar rectangular trapezoids. The calculated areas are summed up and the final result is obtained.
You can simplify your work (eliminate measuring individual slopes and planes) if you have a carefully prepared plan in hand.
Calculation method
It will not be possible to calculate the square footage of the roof of a house correctly unless you figure out exactly what its shape is. In the absence of clear and unambiguous plans, you will have to prepare them yourself, drawing all the necessary drawings by hand. An equilateral trapezoid is calculated taking into account not only the width of the slopes, but also the lengths of the bases and height. The prepared roof plan must reflect all lengths, widths and heights with an error of no more than 1 cm. If it is possible to measure more accurately, you should definitely take this chance.
It is advisable to prepare a plan in several projections at once, and recheck each measurement and each step of the calculation. A mistake can be very expensive, in the literal sense of the word. Determine number square meters You can do it from the ground, from the roof itself, or from the attic.
To increase the accuracy of measurements and calculations, it is recommended to pay attention even to the asymmetry of the edge, to the excessive width of the ridge, to changes in the angles of inclination in different places. A roof sloped at an angle of 9 degrees is 10% larger in size than an identical flat one.
If the slope increases to 56 degrees, the conversion factor already reaches 1.8, and its approximate change with an increase in the angle by 10 degrees is 15%. Angles of inclination of slopes in houses covered with symmetrical gable roofs, are determined depending on the length of the base of the isosceles triangle formed by the slopes. To calculate the overlap, you need to multiply the length of the house by the length of the rafters.
The area of all slopes separately is determined as the length of the house with the addition of the front and eaves overhangs, multiplied by the length of the rafters + the length of the overhang. If the roof is pitched, there is no need to double the resulting number.
For the most accurate calculation of the footage of a triangle or any other geometric figure, the results obtained from the formulas must be increased by 10-15%. This will compensate possible errors and defects when laying roofing material. It will be somewhat more difficult to calculate the roof area for subsequent fire retardant treatment and for impregnation with antiseptic compounds. The methods are approximately the same, but you will also need to take into account the coefficients recommended by the fire inspection. They will allow you to compensate for both calculation errors and overconsumption of impregnating mixtures.
The problem is that the special impregnation is not applied to the roof, and on the sheathing and upper parts of the floors, rafters, trusses and crossbars. But rafters, beams and other similar elements have a much smaller area than the roof itself. And therefore, in most cases, to accurately predict the need for treatment with fire retardants, you will have to enter a coefficient of 1.2. It will successfully “absorb” all the irregularities.
The angle of inclination of the roof is calculated between the inclined rafters and the ceiling. When calculating the surface area that sheets of metal tiles, slate or corrugated sheets will have to occupy, we must not forget that one of the waves is spent on connections with adjacent sheets. Therefore, you will have to add another 10% to the resulting area after all the calculations and adjustments. It is also taken into account that sheet materials measured in linear meters, which will need to be first converted into square ones, and only then compared with the dimensions of the roof. Additionally, you can check yourself by using specialized online calculators directly from major suppliers of selected coverage.
If the roof does not have a wall gutter, add 7 cm to the slopes above the eaves. And in the case where there is a gutter, a cornice, and an overhang, the length can be reduced by 70 cm. It is additionally necessary to calculate the areas of parapets, a firewall and other structures that are not physically connected to the main covering. There is no need to take into account standing seams if individual parts are covered with roofing steel.
You can also ignore the bypass of the base beam roll coverings. Essentially, it does not play a role, just like the arrangement of aprons.
And one more thing about ignored details: there is no need to calculate the roof connections to:
- parapet;
- skylight;
- thermal seam;
- pipe;
- ventilation shaft;
- wall.
Coverings of parts of the same roof located in different planes and separated by other materials are calculated separately. If there is no building design or it raises certain doubts, it is better to measure all values in fact. The effort spent will be repaid a hundredfold; repairing or building from scratch will be much easier. Moreover, the centimeters not taken into account on large-scale plans and diagrams in reality turn into whole meters of error.
