We offer professional free calculation of the rafter system gable roof by using online calculator and the website, 3D visualization and detailed drawings. Detailed calculations of the roof and roofing, all materials, sheathing, rafters, mauerlat. Try the calculation 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 sheets 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 the standard parameters for rafters and sheathing, our article will help you “ Optimal cross-section, pitch of sheathing and rafters depending on the type of roof ».

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! Depending on how accurate the values ​​you enter, the online calculator will be able to calculate the gable roof so reliably.

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 in different angles review, 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.

When we talk about the roof of buildings, the word “slope” refers to the angle of inclination of the roof shell to the horizon. In geodesy, this parameter is an indicator of the steepness of the slope, and in design documentation it is the degree of deviation of straight elements from the baseline. Slope in degrees does not raise any questions, but slope in percentage sometimes causes confusion. The time has come to understand this unit of measurement in order to clearly understand what it is and, if necessary, without special labor convert it into other units, for example into the same degrees.

Calculation of slope as a percentage

Try to imagine ABC lying on one of its legs AB. The second leg BC will be directed vertically upward, and the hypotenuse AC will form a certain angle with the lower leg. Now we have to remember a little trigonometry and calculate its tangent, which will precisely characterize the slope formed by the hypotenuse of the triangle with the lower leg. Let us assume that leg AB = 100 mm and height BC = 36.4 mm. Then the tangent of our angle will be equal to 0.364, which according to the tables corresponds to 20˚. What then will be the slope as a percentage? To convert the resulting value into these units of measurement, we simply multiply the tangent value by 100 and get 36.4%.

How to understand the slope angle as a percentage?

If road sign shows 12%, this means that for every kilometer of such ascent or descent the road will rise (fall) by 120 meters. To translate percentage value in degrees, you simply need to calculate the arctangent of this value and, if necessary, convert it from radians to the usual degrees. The same goes for construction drawings. If, for example, it is indicated that the slope angle as a percentage is 1, then this means that the ratio of one leg to the other is 0.01.

Why not in degrees?

Many people are probably interested in the question: “Why use other percentages for the slope?” Indeed, why not just get by with just degrees. The fact is that with any measurements there is always some error. If degrees are used, installation difficulties will inevitably arise. Take, for example, an error of a few degrees with a length of 4-5 meters can take it in a completely different direction from the desired position. Therefore, percentages are usually used in instructions, recommendations and design documentation.

Application in practice

Let's assume that the construction project country house assumes the device. It is necessary to check its slope in percentages and degrees, if it is known that the height of the ridge is 3.45 meters, and the width of the future dwelling is 10 meters. Since the roof is in front, it can be divided into two right triangle, in which the height of the ridge will be one of the legs. We find the second leg by dividing the width of the house in half.

Now we have all the necessary data to calculate the slope. We get: atan -1 (0.345) ≈ 19˚. Accordingly, the percentage slope is 34.5. What does this give us? Firstly, we can compare this value with the parameters recommended by experts, and secondly, check with the requirements of SNiP when choosing a roofing material. By checking the reference books, you can find out that this level of inclination will be too low for installation (the minimum level is 33 degrees), but such a roof is not afraid of powerful gusts of wind.

The crowning achievement of building a house is always the roof, and what it will be like depends not only on the wishes of the homeowner, but also on how to calculate the angle of the roof.

What do you need before calculating the angle of the roof?

Installing rafter legs usually does not cause difficulties if you have the necessary fasteners, however, when checking the angle at which the slopes will be laid, you can make a mistake if you do not know some of the subtleties. For example, a very high roof in an area with strong winds will be constantly subjected to heavy loads and will eventually be destroyed with a high degree of probability. Therefore, to avoid this, sometimes it is worth giving preference to a low roof that is not too spectacular, but stable. There are many such examples, but let’s consider the factors themselves that influence the height of the roof. What might she depend on?

As has already become clear, before calculating the angle of inclination of the roof, it is first necessary to take into account the climatic features of the region. So, for example, the sharper the gable roof, the worse it holds snow and the easier it flows off. rainwater. However, what are the consequences of such a steep slope, with strong wind, we already know. In places where the sun is hot, it is better to build slopes with a minimal slope or do without them at all, that is, to make a flat roof surface, which receives and transmits heat more strongly, the larger its area. The latter increases in proportion to the steepness of the slope.

The flatter the roof, the higher the likelihood that strong gusts wind and rain will drive moisture under the edges of the roofing.

Among other things, you should consider how the space under the rafter system will be used - as an attic or as a residential attic. In the first case, the allowed distance to the skate is less than the average height of a person. In the second case, it is necessary that there be enough comfortable space for movement, that is, the clearance in the center of the room should be at least 2.5 meters and, preferably, at least one and a half meters at the lowest point of the ceiling. A significant impact on the angle of the roof slope can be exerted by the covering material, which can only be laid at a certain degree of slope.

Calculation of the required amount of attic slope slopes

The most important thing in any room is its effective area, that is, one that can be used for arranging furniture and moving, as well as for storing things. In the attic, it can sometimes be difficult to use some areas of the space where the lowest point of the ceiling cladding is located. However, such places can be reserved for storing things by making built-in cabinets and cabinets there. Another thing is the free movement zone, its area directly depends on the height of the ridge, and therefore the angle of the roof.

Let's look at an example. Let’s say the width of the house is 9.5 meters. If you want space above your head within 3 meters, at least in the center of the room, then the angle between the slopes should be at least 35 degrees, since already at 30 the height of the ridge will be slightly more than 2.5 meters. However, it should be borne in mind that then the width of the space available for free movement (up to a two-meter ceiling level) will be slightly more than 3.5 meters. If you maintain the same height at the lowest points of the sloping ceiling, and at the same time make the roof angle 30 degrees, then the width of the room will be reduced to 2.4 meters. It will be most comfortable in an attic under a roof with an angle of more than 40 degrees, but it should be borne in mind that in such a structure, in comparison with a gentle slope (about 10 degrees), the wind load increases almost 5 times.

In general, the dependence of the roof inclination angle on the height of the ridge only facilitates the calculations of the rafter system.

However, for calculations you need to know the basics of geometry quite well. Most often, the cross-section of the roof structure on the side of the gables is a triangle, equilateral, isosceles, or another type. Accordingly, using the simplest formulas, you can calculate the length of any side and the angle adjacent to it, knowing the base and height. In this case, in addition to the measuring tape, we will need a Bradis table, since we will have to deal with tangents.

So, we look at the pediment and see equilateral triangle, consisting of two rectangular ones, one of the legs of which is common. There is a formula according to which the tangent of an angle A at the base equal to the ratio opposite side to the adjacent one, that is, Tg A = H/(L/2). In other words, in our case this is the height H, divided by half the base L. Let's take the same gable width of 9.5 meters, half of it will correspond to 4.75, by this value we divide the height of the ridge, which we consider comfortable, for example, 4 meters. As a result, we get 4/4.75 = 0.84, look at the Bradis table, look for the corresponding position in the tangent table and see that we need an angle of 40°.

How can the material affect the slope of the roof?

Any roof is a kind of layer cake made of hydro- and vapor barrier, insulation, sheathing and outer covering. All this is laid out on rafter system at a certain angle that limits the use of a particular material. You should mainly focus on the instructions offered by the manufacturer, which also relate to the requirements for the slope of the slopes. Roofing materials can be rolled, stacked (tiles and slates), sheets, as well as flexible pieces, and for each type there is a minimum roof angle.

For roll coverings, a slope of no more than 15 degrees is considered optimal, provided that the material is laid in 2 layers. If the roof is made of three layers, it should be even more flat, about 5 degrees, and additional sheathing is required to increase strength in case of increased temporary load (snow, rain). But there is an exception - a membrane covering, which can be used at any roof slope.

Prefabricated materials also do not tolerate steep slopes, for the simple reason that they can slide down under their own weight at the slightest prerequisite for this, such as a stormy gust of wind. However, the angle cannot be made too small, since in this case the mass of the roofing material will unnecessarily load support structures, that is, rafters, sheathing and other elements. An angle of 22 degrees is considered optimal, which is sufficient to ensure that during rain, moisture flows freely and is not blown under the joints by the wind.

For corrugated sheeting and metal tiles, the minimum slope is 12 and 14 degrees, respectively, gentle enough for precipitation to drain from the roof without compromising its tightness at the joints. The steepness can increase to a greater extent without restrictions, however, taking into account the fact that a large roof area has a significant mass. Also, one should not forget about the wind load and high windage of roofs with an angle close to 45 degrees. The optimal tilt is about 27-30 degrees.

But at soft tiles, which consists of individual pieces of material standard size, the roof angle is related to the density of the sheathing. If the slopes are very flat, then the distance between the slats should be made as small as possible. This is due to the fact that snow masses can become an unbearable load for the coating. In the case when the steepness of the slopes is maintained within 30-40 degrees, the sheathing pitch is allowed to be larger, up to 45 centimeters.

It is difficult to imagine any building without a roof. The roof must protect the building from the effects of natural precipitation, have fire-resistant and waterproof properties, and ensure effective removal of precipitation. Durability of use of the building and its individual elements largely depends on quality roof. For achievement best results worth using more simple types pitched roofs: single-pitched, double-pitched, hip, half-hip, mansard.

The minimum slope of a metal roof should be 14 degrees.

Basic data

Schedule for choosing roofing material depending on the roof slope.

The permissible angle of inclination of a metal roof is usually measured with your own hands based on climatic conditions the area in which construction is taking place and the roofing material. The minimum inclination angle should be 110°, the maximum inclination angle can be determined by analyzing weather conditions, its value can be 45°. and more. For warmer, drier climates, a shallower roof is used. A steeper slope angle makes it possible to minimize snow accumulation and, accordingly, reduce the snow load. For example, a slope of 45° allows you to almost ignore the weight of the snow cover.

Along with this, the increased angle of inclination sharply increases the wind pressure on the roof. With a slope of 45°, the wind pressure is 5 times greater compared to 11°. Consequently, for a larger angle of inclination, there is a need for more slats to strengthen the sheathing and rafters. Its cost directly depends on the slope of the roof.

For a roof with a slope of about 40-45°, more materials are needed (about 1.5 times) than for flat roof, and for 60° 2 times more roofing materials are required. When choosing a configuration, it is important to remember that the angle of inclination directly depends. Taking into account the angle of inclination allows you to determine the materials for the roof, as well as calculate the layers of the roof and its area.

Roofing materials according to their properties (technical, economic, physical) are grouped 1-11.

They are shown on the graph by arc-shaped arrows. Slope lines show the slope of the slope. The highlighted (bold) line on the graph indicates the ratio of the full height of a given ridge h to half of its usual height of ½. The ratio 1/2 indicates that the vertical segment h is located on the horizontal segment ½ twice. The inclined line on the semicircular scale indicates the slope angle in degrees, and the vertical scale indicates the roof slope in %.

This is how the minimum slope for certain roofing materials is calculated. As an example, using this graph we will calculate desired angle slope for a given roof using metal tiles.

How to measure slope

On the graph we are looking for an inclined line with which arc-shaped arrow 2 joins. The intersection of the inclined line with the vertical scale determines the minimum acceptable slope for a given roof, which is 50%. We know that the slope of the slope is determined by the ratio of the height of the ridge to half of its depth. Let's do the calculation this way:

i = 10 meters (laying)

h = 4 meters (ridge height)

we get

i= h / (1/2) = 4 / (10/2) = 0.8

To measure the slope in %, this ratio is multiplied by 100

Thus, a slope of 80%, subject to construction standards, will ensure sufficient discharge of rainwater from the entire area. For roofing made of rolled polymer-bitumen, bitumen and mastic materials with a slope of 10°, a protective layer is required for the main waterproofing cover of gravel or stone chips, which has a frost resistance grade of at least 100. The same protective layer is used for roofing with the help of film roll materials with an angle of up to 2.5%. The gravel protection layer should be 1-1.6 cm thick, and the coarse-grained topping layer should be 0.3-0.5 cm thick.

Moreover, on roofs with a slope of up to approximately 2.5% using elastomeric film materials in rolls made with loose masonry, a weighting layer of gravel is required at the rate of 50 kgf/sq.m.

On roofs made of bitumen-polymer or bitumen coatings in rolls with a slope angle above 10% upper layer The waterproofing cover is made from coarse-grained powder. On roofs made of mastic materials with an angle greater than 10%, a protective layer of paint compositions is provided.

When creating a roof from asbestos cement sheets, as well as corrugated sheets and metal tiles with a slope of up to 20% over the entire area, it is necessary to seal the joints. No more than 5% deviation from small-piece materials can be allowed. By making these calculations, you can find out the area of ​​the attic or attic.

Units and tools

To the base metal structure Built-in digital display with control elements.

The magnitude of the slope in all drawings can be indicated in degrees or as a percentage, and it itself is indicated by the letter “i”. IN currently There are no strict rules on how to designate this value. The unit of measurement is degrees or percent (%).

The slope angle is measured in two ways:

1. A special inclinometer.
2. In a mathematical way, using calculations.

An inclinometer is a special rack with a frame, which has an axis between the slats on which the pendulum is mounted, and its own division scale. When this rod is located in a horizontal position, the pendulum on its scale is deflected by zero degrees. To measure the slope of the slope, the instrument rod is placed perpendicular to the ridge, in a vertical position.

The scale determines the deflection angle of the pendulum, which indicates the slope of this slope of a given roof in degrees. This determination method is used very, very rarely. On this moment Many geodetic instruments have been developed to determine these quantities and special inclinometer levels, both drop and electronic.

Mathematical calculation

1. Vertical height (denoted as H) - the height from the top point of a given slope (usually counted from the ridge) to the lowest point (the so-called cornice).
2. Laying is a horizontal interval from the lowest point of a given slope to its highest point.

The slope of the roof (its value) using mathematical calculation is found as follows.

The inclination angle of an individual slope i is expressed through the ratio of the measured roof height H to the installation distance L. Thus

To accurately determine this value as a percentage, the ratio i is multiplied by 100. Then, to determine its value in degrees, we convert the percentages to degrees.

To fully understand this method, here is a visual calculation:

height is 3.0 m,

laying length is 5 m.

Using the formula we calculate i:

We calculate interest

Convert to degrees. We get 31 degrees.

During the construction of the roof, it is necessary to pay equal attention to both aesthetic factors and design. We propose to consider how to calculate the angle of inclination of a roof made of corrugated sheets, metal tiles and slate, as well as how to determine the optimal slope of a hip and pitched surface.

Requirements for slopes

The slope of the roof is the angle formed between the rafters and the overlapping plane (roof covering material).

Photo - Roof angle

Experts often calculate this indicator using a simple equation:

Here we see the following values:

• h – by traditional definition, this is the height, in in this case, this is the determination of the height of the ridge board above the floor material;
• L is the distance that is covered by a given section of the roof, or in other words, the width of the building. It is important to remember that if you have broken roof, then this value varies from one slope to another, so the calculations become a little more complicated.

As an example, if your house is 10 meters wide and the ridge is 4 meters high, then the size of the roof slope will be:

(1/10*2) / 4 = 0.2, or if you need to convert this number into a percentage, then multiply it by 100, you get 20%. The angle is also expressed in degrees; its value does not change due to conversion, and now all systems are equally popular. It is preferable to use degrees, because... in them we see the real magnitude of the geometric value.

In order not to get confused yourself and not to complicate the work of the builders (if you order a service from a certain company), you can use our table, in which, knowing the data in percentage or degree of slope, you can select the appropriate angle:

The roof must be designed together with the entire structure, but as you understand, during the construction process, you can deviate a little from the received readings. If such a need arises, you can change the height of the ridge to change the slope angle. After you have calculated the required slope, you need to calculate what height of the ridge will be optimal for you. To find out these values, we again need a table that determines the height coefficient of the ridge board:

To process the value obtained in the table, you must multiply the degree from half the overlap, which was determined in the first table, by the coefficient from the second. The resulting value characterizes the height of the roof ridge. Exactly the same action is carried out to determine the recommended height of the ridge pitched roof, only in this case it is necessary to expect to take the full overlap area.

If you have a hip or envelope roof, then the end sides are measured from the middle, to the place on which the slope rests. To determine the height of the ridge along a certain section of the roof, it is necessary to draw special marks along the length of each wall where the roof slope runs or install beacons made of nails or screws. It is advisable to place them clearly in the center of the wall. Between the beacons, which are located opposite each other, you need to stretch a thread or mounting tape.

Using a meter or level, we find the center of the string and mount a thin strip on it, which will be located at an angle of 90 degrees in relation to the ceiling. Be sure to check this with an angle, level or construction protractor. After moving the rope along the plank, you can measure the angle of the wall and see where the optimal roof slope is. Once you have identified a location, mark it with a marker, chalk or nail. If you saw off the bar in this place, then you will have ready-made template, with which you can cut any number of ridge boards that fully meet your requirements.

Calculating the angle of inclination of a roof is quite a complex and painstaking job; even the slightest flaw can cause poor ventilation, water runoff, and destruction of the roof and under-roof space.

Video: roof installation

Is a roof slope necessary?

Many believe that a gable roof will in any case perform its functions, regardless of its angle of inclination, material, etc., but still, it is better to listen to the advice of experts and find out which value is optimal for you.

Installing a sloped corner roof has its advantages and disadvantages. Which dignity has the angle of a seam, sand, mansard, sloping or simple gable roof in the chalet style:

1. When water hits the roof, it flows down without lingering on the surface of the building. This significantly increases the durability of the roof, promotes its self-cleaning and strength;
2. For a country house or cottage, it is very important to calculate what pressure the snow exerts on the roof surface, but if the angle of your roof is 45 degrees or more, then this indicator is not taken into account, because snow practically does not linger on the roof surface;
3. There is no need to install a complex drainage system; water is drained from the surface of the roofing material due to the angle of inclination and the force of attraction;
4. You can install an under-roof space of any shape; it is possible to organize greenhouses in the attic, separate living rooms or verandas;
5. Alpine roofs are known to have a very high structural pressure, which requires a special selection of fasteners. If you choose the correct permissible angle of inclination of the rafters of a hipped or alpine roof, then they can be mounted with simple self-tapping screws and nails;
6. This is especially convenient in Khrushchev-era buildings, where there is no drain at all, because... when organizing water drainage, you can build a separate utility room, which will serve as an attic, like in a private house.

But not everything is as good as it seems. The fact is that the organization of the roof slope also has negative sides:

1. Very high consumption of roofing material, soft bitumen shingles, ondulin for a sloping roof is necessary almost twice as much as for a flat one;
2. Along with the amount of roofing materials, their weight will also increase.
3. When there is wind, a large load will be generated, which will negatively affect the entire structure of a private house, gazebo, garage, bathhouse and any other room;
4. It is also necessary to understand that when pitched roof, calculating the size of the drain will be slightly complicated by the fact that the pressure of the water flow will be much higher than with a simple flat surface. Water will flow down the coating with greater speed and pressure;

In addition to all the factors listed above, the roof slope must comply with GOST. There are no strict requirements regarding the canopy, ridge height, slope, but the angle must be at least 14 degrees, although in utility rooms(hangar, balcony, dacha), you can deviate from this value.

1. In Russia, especially in middle lane, winters are quite cold, so it is necessary to take into account average annual precipitation (snow, water, hail) when calculating the roof angle;
2. Snow accumulates most on surfaces with a roof slope of 20 to 35 degrees;
3. To count correct angle, it is also necessary to take into account the material, its quantity and properties. For example, steel has much less flexibility than polycarbonate, so build from it difficult angles it will be heavier;
4. The main disadvantage is that the covering on a sloping roof is very susceptible to various loads, so take care to strengthen the rafter system;
5. To protect the building from the possibility of water leakage, cover the roof from the inside using sandwich panels, film or corrugated sheeting;
6. For dormer window you need to calculate the level of inclination that follows the slope of the roof.