Calculation of the rafter system of a gable roof. Calculation of a gable roof: principles for selecting proportions and counting consumables Gable roof with different slopes online calculation

Roof erection is one of the responsible construction processes, the quality of which directly depends on performance characteristics the roof itself and the entire building. Construction should begin with the calculation and design of the roof structure on paper. One of the most important data for calculation is the height of the ridge, in connection with which the angles of inclination of the slopes, the type of roof and the number of building materials. Let's figure out how to independently calculate the height of the roof of different structural types.

In this article

Preparation for calculations

Creating a roof plan and calculating a number of its parameters has important for subsequent installation. Paying in advance helps:

• Calculate in advance the amount of building materials needed and do not make any mistakes when purchasing them, up or down.
• Even at the design stage, think over and distribute various systems, such as drainage, snow retention, etc., and determine their place in the future project.

• house dimensions;
• plans for the use of under-roof space;
• the planned shape of the roof and the number of its slopes;
• slope angle;
• stress on roof structure: wind, snow, etc.;
• type of roofing.

In this article we will look at how to correctly calculate the height for the three most common roofing structures.

Calculating the height of a gable roof

The gable roof type is easy to design and construct. The design of this type implies the presence of two planes that stand on opposite load-bearing walls and, meeting at the ridge, form a triangle with equal sides.

Calculating the height of the ridge two pitched roof is directly dependent on the angle of inclination of the slopes.

The choice of roof slope should not be arbitrary. Its value depends on wind and snow loads, the rules for determining which are regulated by SNiP. The recommended slope for the regions of central Russia is 30-45°. Also, the choice of slope of the roof slopes is influenced by the selected roofing material.

Having decided on the slope of the slopes, you can calculate the height of the roof of the house. Its value is calculated using the well-known geometric formula:

a = b * tan α

where a is the desired value, b is the value of half the width of the house, tan α is the tangent of the selected angle, which can be found in a specialized table.

With a slope slope of 45°, the elevation of the ridge beam will correspond to the width of the house.

Calculation of a hipped structure

A roof with four slopes is the most resistant to wind loads. There are two types of hipped roof:

• Tent - all slopes converge at a single point at the top of the structure.
• The hip has two triangular and two trapezoidal slopes, the latter connected at the top by a ridge beam.

It is possible to calculate the height of the ridge for both types of roof using the formula used for the gable structure. However, to carry out a more thorough calculation and compilation detailed diagram it is also necessary to calculate the lengths of the rafters, and for hip roof- length of the ridge beam.

Calculating the rise of the ridge is most often associated with the desire to arrange a living room. For these types of hipped roofs, the elevation of the structure to create a living space must be at least 2.5 m.

Mansard roof design

A mansard or broken roof also has two slopes, the feature of which is a characteristic break. It allows you to increase the space under the roof and makes the broken structure one of the most suitable for creating an attic.

Calculating the height of a broken-type roof begins with calculating the angles of inclination of all pitched roof surfaces. Construction experts recommend determining the angles of inclination attic structure practical method using the golden ratio rule. To do this, you need to write a sketch of the future roof in a circle on paper. This method will allow you to avoid design defects in which the broken structure does not look aesthetically pleasing.

Design and calculations are important and fundamental stages in creating a roof. Their literate and correct execution is the key to constructing a reliable and aesthetically attractive roof that will last for many years.

Calculating the required roof height, as well as its area, is one of the most important tasks when planning and building a private house.

● From the height of the ridge The angle of the slope directly depends: the greater the height of the ridge, the greater the angle of the slope. If the angle of the slope is too small, then in winter a snow cap will certainly form on the roof, which not only threatens the roof, but also puts serious pressure on the entire structure. If the height of the slope is too high and, accordingly, the coverage area is significant, then due to strong gusts of wind it may simply not stand up.

● To the main ones types of pitched roofs include: single-slope, double-slope (aka gable), four-slope. In private housing construction, a gable roof is one of the most common. This is a fairly simple design - two slopes rest on separate and overlapping pairs (connected by rafter sheathing). At the ends of the roof there are two gables, which include the so-called " dormer windows", contributing to the illumination of the interior space in the attic.

● When calculating the height of a gable roof First of all, you need to decide what angle of inclination of the slopes will be the most rational. To do this, it is better to contact regulatory documents, which regulate this type of construction work:
SP 20.13330.2011 Loads and impacts. Updated version of SNiP 2.01.07-85*. This set of rules contains a formula for calculating the snow load for roofs with a gable roof and provides a formula for wind influence. The permissible angle of roof inclination may vary depending on the climatic and weather conditions of a particular region. For central regions RF permissible tilt angle is within 30-45º.

● After the angle of inclination is determined , you can begin to calculate the height of the roof ridge. Let's use some simple techniques from practical geometry.

Imagine the roof in the form of a triangle. Necessary ridge height will perform the function of an unknown leg A, which will divide the area of ​​the triangle into two more, but already right triangles. Formula for calculating leg: A = B x tgA. The second leg B is 1/2 the width of the house. Gable roof design It is usually carried out along the long side of the building. The tangent of the angle is determined from the table based on the value of the degree of slope.

Roof angle, in degrees Tangent tg A 5 0,09 10 0,18 15 0,27 20 0,36 25 0,47 30 0,58 35 0,7 40 0,84 45 1,0 50 1,19 55 1,43 60 1,73

We substitute the obtained values ​​into the formula: A = B x tg A and obtain the required height of the roof ridge.

● Let's determine the height gable roof For example:

The building has dimensions of 6x9 meters, the roof slope is 40 º . We divide the width - 6 m in half: 6: 2 = 3. This is leg B - its value = 3. From the table we determine that tg 40º = 0.84. For search optimal height ridge, we substitute all the original values ​​into the formula: A = 3 x 0.84 = 2.52. It turned out that the most acceptable height of the ridge is 2.52 m.

● Roof angle during the construction of a private house.

● Simple calculations required height of gable roof when designing a private house, they will help in the future to avoid serious problems in the operation of one of the main components of the entire structure.

The roof of a building is designed to hold external loads and redistribute them to load-bearing walls or supporting structures. These loads include weight roofing pie, the mass of the structure itself, the weight of the snow cover, and so on.

The roof is located on the rafter system. So called frame construction, on which the roof is fixed. It accepts all external loads, distributing them across supporting structures.

The rafter system of a gable roof includes the following elements:

• Mauerlat;
• Struts and braces;
• Side and ridge purlins;
• Rafter legs.

A rafter truss is a structure that includes all of the listed elements with the exception of the Mauerlat.

Calculation of gable roof loads

Constant loads

The first type refers to those loads that always act on the roof (in any season, time of day, and so on). These include the weight of the roofing pie and various equipment installed on the roof. For example, weight satellite dish or aerator. It is necessary to calculate the weight of all truss structure along with fasteners and various elements. To perform this task, professionals use computer programs, as well as special calculators.

Calculation gable roof is based on calculation of loads on rafter legs. First of all, you need to determine the weight of the roofing cake. The task is quite simple, you just need to know the materials used, as well as the dimensions of the roof.

As an example, let’s calculate the weight of a roofing cake with ondulin material. All values ​​are taken approximately; high accuracy is not required here. Usually builders perform calculations of the weight per square meter of roofing. And then this indicator is multiplied by total area roofs.

The roofing pie consists of ondulin, a layer of waterproofing (in this case - insulation on a polymer-bitumen basis), a layer of thermal insulation (weight calculation will be carried out basalt wool) and lathing (the thickness of the boards is 25 mm). Let's calculate the weight of each element separately, and then add up all the values.

Calculation of the roof of a gable roof:

1. A square meter of roofing material weighs 3.5 kg.
2. A square meter of waterproofing layer weighs 5 kg.
3. A square meter of insulation weighs 10 kg.
4. A square meter of sheathing weighs 14 kg.

Now let's calculate the total weight:

3.5 + 5 + 10 + 14 = 32.5

The resulting value must be multiplied by the correction factor (in this case it is equal to 1.1).

32.5 * 1.1 = 35.75 kg

It turns out that a square meter of roofing cake weighs 35.75 kg. It remains to multiply this parameter by the roof area, then you can calculate a gable roof.

Variable roof loads

Variable loads are those that act on the roof not constantly, but seasonally. A striking example is the snow in winter time. Snow masses settle on the roof, creating additional impact. But in the spring they melt, and accordingly, the pressure decreases.

Variable loads also include wind. This is also a weather phenomenon that does not always work. And there are many such examples. Therefore, it is important to take into account variable loads when calculating the length of the rafters of a gable roof. When calculating, you need to take into account many different factors affecting the roof of a building.

Now let's take a closer look snow loads. When calculating this parameter, you need to use a special map. The mass of snow cover is marked there different regions countries.

To calculate this type of load, the following formula is used:

Where Sg is the terrain indicator taken from the map, and µ is the correction factor. It depends on the roof slope: the stronger the slope, the lower the correction factor. And here there is an important nuance - for roofs with a slope of 60 o it is not taken into account at all. After all, the snow will simply roll off of them, and not accumulate.

The whole country is divided into regions not only by the mass of snow, but also by the strength of the winds. There is a special map on which you can find out this indicator in a certain area.

When calculating roof rafters, wind loads are determined using the following formula:

Where x is the correction factor. It depends on the location of the building and its height. And W o is the parameter selected from the map.

Calculation of the dimensions of the rafter system

When the calculation of all types of loads is finished, you can proceed to the calculation of dimensions rafter system. The work performed will differ depending on what kind of roof structure is planned.

In this case, a gable one is considered.

Section of the rafter leg

The calculation of the rafter leg is based on 3 criteria:

• Loads from the previous section;
• Remoteness of the railings;
• Rafter length.

There is a special table of sections of rafter legs, in which you can find out this indicator based on the criteria described above.

Length of rafters in a gable roof

For manual calculations you will need basic knowledge geometry, in particular the Pythagorean theorem. The rafter is the hypotenuse of a right triangle. Its length can be found by dividing the length of the leg by the cosine of the opposite angle.

Let's look at a specific example:

It is required to calculate the length of the rafters of a gable roof for a house with a width of 6 m, in which the slope of the slopes is 45 o. Let L be the length of the rafters. Let's substitute all the data into the formula.

L = 6 / 2 / cos 45 ≈ 6 / 2 / 0.707 ≈ 4.24 meters.

You need to add the length of the visor to the resulting value. It is approximately 0.5 m.

4.24 + 0.5 = 4.74 meters.

This completes the calculation of the length of the rafters for a gable roof. It was manual method completing the task. There are special computer programs designed to automate this process. The easiest way is to use Arkon. This is completely free program, which even a person with little computer knowledge can easily understand.

It is enough to simply specify the input parameters based on the size of the house. The program will independently perform calculations and show the required cross-section, as well as the length of the gable roof rafters.

The roof is an important structural part of the house, performing a number of essential functions. It protects against atmospheric attacks and removes precipitation, provides insulation and makes a significant contribution to the formation of your own building style. In order for such a significant structure to cope “excellently” with the entrusted work, it is necessary to thoroughly think through the project and scrupulously understand the dimensions.

Careful analysis and calculation of a gable roof is required by both independent craftsmen and country property owners who resort to the services of construction organizations. Let's figure out how to do this correctly.

The roof, which resembles an inverted letter V in cross-section, leads the list for a reason pitched structures. In terms of simplicity of construction and efficiency, the gable roof has practically no rivals. Tested in practice for centuries, they are the basis for the construction of most roofing structures.

Simple pitched planes do not require complex cutting of coatings and other materials, which results in an impressive amount of waste. No specific tricks are needed to implement intricate configurations. Precipitation does not last long inclined surfaces, so there is no need to strengthen the waterproofing. As a result, installing a gable roof is often cheaper than a single-pitch roof.

A roof with two slopes can be an independent object or part of a complex of structures of a similar or different shape. The simplest version does not have built-in dormer windows and canopies over entrance porch, i.e. there are no additional fractures, ridges and accompanying valleys.

The absence of convex and concave corners deprives the master of the “pleasure” of suffering through a number of difficult operations. Again, the owners will not receive imaginary pleasure from leaks, which often appear at the joints of pitched roof elements.

In principle, no one is stopping lovers of fancy architecture from equipping two slopes with numerous built-in structures. True, there are climatic restrictions: in areas with high amounts of winter precipitation, the construction of roofs with numerous components is undesirable. In the grooves formed by the excesses, favorable conditions for accumulation of snow deposits. You will have to clean them off more quickly than usual, and excessive zeal in removing snow can cause damage to the coating with all that it entails.

However, adherents of simple and clear forms should not relax either. The angle of the roof configuration must be ideally selected and calculated, otherwise it will not be able to flawlessly perform the entrusted work.

Despite the deceptive simplicity, there are pitfalls in determining the optimal shape of a structure. It is impossible to overcome and bypass them without knowledge of technological subtleties, because all the parameters of the structure are interconnected:

• The width of a gable roof depends on the dimensions of the box and the type of coating, which in turn affects the selection of the steepness of the slopes.
• The roof slope depends on climatic features construction area and type of roofing material.
• The combination of the above circumstances, width and slope, determines the height of the structure, which ultimately may not meet architectural requirements and aesthetic considerations.

The impeccably designed roof has all the proportions chosen perfectly. Its width and height determine the rise and slope required to drain sediment in a particular area. It is not possible below technical reasons, the higher is expensive and unwise unless the unique architecture requires it.

Please note that as the steepness increases, the construction budget increases. Roofing material is selected according to the slope. Based on its weight and specifics, they design and calculate rafter frame. The calculation of the rafter frame is carried out taking into account the listed parameters and taking into account the loads acting from the outside on the structure.

The interdependence of the proportions of the roof, the complexity of the rafter frame structure and the nuances of selecting the coating makes it necessary to determine best shape through banal selection. If something does not fit, the supporting structures are replaced or strengthened. Fortunately, there is now a sufficient assortment on the construction market, and all sorts of methods have been developed to strengthen the structure.

If you are afraid of the upcoming calculations and data shuffling, it is better to resort to a win-win solution - standard project. It’s not for nothing that abroad all the houses of one locality are equipped with roofs equal height and covered with a material of equal color and characteristics. Typing allows you to maintain landscape identity and reduce design costs.

However, even a standard design solution is not a panacea for technical problems and aesthetic shortcomings. We must not forget about the individual dimensions of the box over which it is planned to build a roof. Compatriots deny equalization in height and steepness, therefore it is still advisable for us to understand the proportions of the roofing structure.

Step-by-step calculations

The configuration and dimensions of any pitched roof are determined by the rafter frame. Slopes are laid on the edges of the rafter legs, forming a dihedral angle. They construct rafter systems from rolled metal and wood, and use industrial-made structures and lumber in construction.

Let's look at the options available to put in the effort independent master, i.e. construction method of constructing a roof frame from lumber.

Stage #1 – choosing the type of rafter system

The method of constructing a gable roof is indirectly related to the dimensions, but without taking into account the difference in the design of structures it will be difficult to understand the geometric parameters.

Two traditional technologies are used in the construction of gable roofs:

• Layered, according to which the top and bottom of the rafters have a strong point of support. The lower support is the walls of the house, equipped with a Mauerlat. The top of the layered rafter legs rests on a purlin that forms the ridge. The purlin is supported on a support system specially constructed for it, on interior wall or on stone gables of boxes erected before the roof structure. The layered method is mainly used when arranging large houses with internal load-bearing wall or next to the columns.
• Hanging, according to which the tops of the rafters rest only on each other. The walls serve as support for the bottom, as in the previous case. The hanging rafter legs form an equilateral triangle, the base of which is called a tie. Taken together, such a system does not create thrust, i.e. does not transfer the bursting load to the walls of the box. Rafter triangles are installed either ready for installation, i.e. assembled on the ground, or constructed from individual rafters on site. The absence of an upper support makes adjustments to the scope of use: the hanging method is used in the arrangement of only small buildings with small spans.

Schemes of rafter systems of both types include a minimum structural elements when covering boxes up to 8-10m wide.

When constructing larger spans, there is a danger of deformation of the rafter legs. To eliminate sagging and deflection wooden parts from lumber, install reinforcing elements: struts, contractions, side girders, etc.

Additional details provide rigidity and stability large structure, but increase the load. We have already discussed how the total load is determined and produced.

Stage #2 – width calculation

Both types of wooden rafter systems are constructed on floor beams or on a mauerlat. How the roof width is calculated depends on the type of base:

• When mounted on floor beams, they form the eaves overhang, i.e. determine the dimensions of the roof.
• When installed on a Mauerlat, the width of the roof is determined by adding three values. You need to sum up the width of the box and two projections of the width of the eaves overhang. However, the calculations use only the load-bearing part of the roof width, equal to the width of the box.

Mauerlat function in frame buildings performs top harness, which at the same time connects disparate elements into a single frame. IN wood construction The mauerlat is the upper crown, folded with timber or logs.

In the case of using the “beam” scheme of the device, so-called matrices are used - bars or logs laid under the upper crown of the foot as an overlap.

The eaves of roofs mounted on a mauerlat can be formed directly by rafter legs, fillets sewn to them or a brick protrusion. The last option, naturally, is used when constructing brick walls. The choice of overhang width is dictated by the type of roofing and the material from which the walls are made.

• For slate roofing no more than 10cm;
• For bitumen shingles in the range of 30-40cm;
• For metal tiles 40-50cm;
• For profiled sheet 50cm;
• For ceramic tiles 50-60cm.

Walls made of logs and timber require enhanced protection from slanting rain, so the overhangs above them are usually increased by 10-15 cm. If the maximum width of the overhang recommended by the manufacturer is exceeded, it is necessary to take measures to strengthen it.

It is possible to install external struts on walls or support pillars, which can simultaneously play the role of structural elements of a terrace, porch, or veranda.

Stage #3 - determining the slope

The angle of inclination of the slopes is allowed to vary within wide limits, on average from 10º to 60º with permissible deviations in both directions. Traditionally, both planes of a gable roof have equal angles of inclination.

Even in asymmetrical designs for residential buildings, they are mainly located under equal angle, and the asymmetry effect is achieved by constructing slopes of different sizes. Most often, differences in the slope of the main parts of the roof are observed during the construction of country houses and household facilities.

The procedure for determining the optimal slope of a gable roof is significantly influenced by three factors:

• The type of covering, coupled with the weight of the sheathing intended for it. The type of roofing material determines the installation technology and the method of constructing the base for its fastening. The denser the roof is, the lower the slope can be. The fewer overlaps and joints between the covering elements, the lower the roof is allowed to be. And vice versa.
• The weight of the roof together with. A heavy coating located at an angle to the horizon presses on the base only with its projection. In short, the higher the slope, the less mass is transferred to the floor. Those. Under a heavy roof you need to build a steep roof.
• Climatic specificity of the region. A high slope facilitates the rapid removal of snow and water, which is highly desirable in areas with significant levels of precipitation. However, high slopes are very sensitive to the effects of winds that tend to overturn them. Therefore, in regions with characteristic strong winds, it is customary to build flat structures, and in areas with abundant precipitation, roofs with a high slope.

In the regulatory documentation used in calculating angles for the construction of gable roofs, there are units that can confuse home builders who are inexperienced in roofing. The simplest quantity is expressed in dimensionless units, the most understandable – in degrees.

The second version conveys the ratio of the height of the roof to half its width. To determine it, a line is drawn from the central point of the ceiling to the top of the roof triangle. A real line is drawn on the house diagram, imaginary on the site. The value is indicated either as a percentage, or in the form of a mathematical ratio such as 1: 2.5... 1: 5, etc. The percentage is trickier and more inconvenient.

Stage #4 - determining the height of the ridge

A roof with two slopes may or may not have an attic at the request of the owner. It is not allowed to install gable roofs in attic spaces. useful premises. This is what it exists for. However, the height of the attic used for maintenance and inspection of roofs at an angle is not arbitrary.

According to the requirements of the fire service, there must be at least 1.6 m from the top to the ceiling. The upper limit is dictated by the aesthetic beliefs of the designers. They claim that if the height of the roof is greater than the height of the box, then it seems to “press” on the building.

The height of the ridge top for those arranged on beams hanging roofs The easiest way to determine this is by drawing:

• Draw a diagram of the house box to scale.
• We are looking for the middle of the upper floor.
• From the middle up we lay the axis of symmetry.
• We put half the width of the roof in any direction from the middle - we get the extreme point of the overhang.
• Using a protractor from extreme point We draw a straight line over the overhang at an angle recommended by the roofing manufacturer. The point of its intersection with the axis will be the top of the roof. Let's measure the distance from the top to the ceiling and get the height.

To get a complete picture, you need to draw the second slope on the diagram in a similar way. Parallel to the lines of the drawn slopes, two more lines must be drawn at a distance equal to the thickness of the rafter legs on the same scale.

If you are not satisfied with the roof configuration, you can “play” with the height on paper, changing the position of the apex point and the slope of the roof within reasonable limits. The same manipulations can be carried out in one of the drawing programs.

When drawing the outline of a roof constructed using layered technology, the thickness of the purlin beam should be taken into account. With impressive power, it will slightly shift the position of the slopes.

Craftsmen believe that calculations of the elements of the rafter system for the construction of a gable roof can generally be reduced to calculating only the cross-section of the purlin. This is the most loaded element; all the others have the right to be thinner. For example, if calculations show that for ridge girder If you need material 100x150mm, then for rafters, supports, struts, 50x150mm boards are enough.

The process of finding the height of structures with overhangs formed by fillies is not much different from the method described. It’s just that the slope angle is drawn not from the extreme point of the overhang, but from the lower attachment point of the rafter to the mauerlat. In any case, it is better to select variations in the slope and size of the gable roof planned for construction on “paper” than on the construction site.

Stage #5 – calculation of material consumption

A normal owner thinks about the construction budget ahead of time. True, the preliminary estimate, by definition, will contain inaccuracies. The process of erecting a gable roof will impose its own adjustments on the initial calculation of the material, but it will help to find out the volume of the main expenses.

The preliminary estimate should include:

• Beam for installing a mauerlat. IN housing construction lumber with a cross-section from 100×150mm to 200×200mm is used. The footage is calculated around the perimeter of the box with a 5% margin for processing and connections. Similar material is purchased for the device of the bench, if it is designed.
• Board for making rafters. Most often, for the manufacture of rafter legs, material with a cross-section from 25×150mm to 100×150mm is used. The footage is determined by multiplying the length of the outer edge by the quantity. The material is purchased with a margin of 15-20%.
• A board or block for making struts, ties and supports with a section of 50×100, 100×100mm, depending on the project. You also need a reserve of about 10%.
• Material for sheathing. Its consumption depends on the type of finishing coating. The sheathing is constructed either solid, if it will be made, or sparse under corrugated sheets, metal tiles, ordinary tiles, slate, etc.
• Rolled waterproofing, the footage of which determines the type of roof and the steepness. High roofs are covered with a waterproofing carpet only along the overhangs, ridge and in convex or concave corners. Gently sloping ones are covered with a continuous carpet.
• Finish coating. Its quantity is calculated by summing up the areas of the slopes. If there are embedded dormer windows, then their areas are also calculated. They just calculate it as a rectangle, and not in fact. The amount of stock for installation is recommended by the coating manufacturers.
• Material for cladding gables and overhangs.
• Corners, plates, screws, staples, nails. Anchors and studs are needed, their quantity will be determined by the project.

You will also need shaped elements for arranging through passages through the roof, valleys, overhangs, and ridge. The sketch of the estimate presented is valid for a cold structure. For an insulated roof, you will need to purchase insulation and vapor barrier film, a block for counter lathing and material for lining the roof from the inside.

What is important to know for calculations and the dangers of errors

1. Types and shapes of modern roofs
2. Ridge run and slope angles
3. Calculation of roof heights of different shapes
4. Roof calculation using online resources
5. What to consider when starting roof calculations

The final stage of building any home (whether it is a spacious main dwelling or a small country house) is the arrangement of the roof. It is this that gives the exterior a presentable and complete appearance. But at the same time, it performs a very important function - it retains heat, creates a cozy, most comfortable and pleasant atmosphere inside. It is this element of any structure that, without exaggeration, is called one of the most important.

What does the height of the structure depend on and what is taken into account when performing pre-installation calculations

It is especially important to know how to calculate the roof height for a house, and to understand exactly how to do it correctly. That is why you need to spend some time studying this issue. Inaccuracies made in pre-installation calculations lead to serious problems, which are then too difficult to cope with. Often, to eliminate errors, you have to start roofing work all over again.

For example, if the slopes are made with a small angle of inclination, then winter snowfalls will cause serious damage to such a structure (due to the accumulation of snow, there is a risk that the roof will break). It is logical to assume that you can simply do a high skate and all problems will be solved. But this is not true either, because a roof that is too high is most vulnerable to gusts of wind.

• general square footage of the structure;
• climatic conditions (as you may have guessed, sloping roofs, which are optimal for warm continents, are not recommended in regions with snowy winters);
• material for roofing, as well as lathing;
• selected form;
• height of the main building;
• personal preferences and tastes of the owner.

The design parameters are largely influenced by a number of other factors, for example, there is a direct dependence on the layer of insulation installed or the installation of snow guards. The dimensions of the ridge are related to the characteristics of the rafter system, but at the same time they can increase the total area of ​​the roof and the amount of materials required for its arrangement.

Everything described above confirms the fact that the strength of the structure, the durability of its operation, aesthetics and harmony depend on the size of the roof. appearance the buildings.

What are the common types of modern roofing structures?

The type of roof has the most direct impact on the calculation and the formulas used for it, as well as on the amount and, therefore, on the consumption of material that needs to be purchased for roofing.

Today the following structures are most often erected:

• single-pitched (it is preferable to use it for outbuildings);
• gable (most popular for residential buildings);
• hipped. Also an excellent choice for residential buildings. There are a variety of options here: spectacular hipped ones (their characteristic feature is the same size and shape of all slopes) or complex hip ones (their feature is the participation of two triangular hips and two slopes with a break (trapezoid shape));
• attic (consists of two slopes, but always with a break). This break allows you to increase the area of ​​the attic.

Ridge and determination of rational slope angles

To calculate different roof shapes, the size of the ridge is used. This name refers to the upper, horizontally located edge of the structure, which was formed at the intersection of two roof slopes (inclined planes).

There is a ridge on all types of roofs, except hipped and domed ones.

If the design , then there is only one, but if it is complex, then two or more skates are formed. During the construction of the roof, the rafter legs rest on the ridge purlins, and based on what roofing material is chosen for the final covering, the base of the ridge is selected.

Knowing how to calculate the height of the roof correctly is necessary both for the construction of a reliable and robust construction, as well as in order to predict preliminary construction costs and plan the budget. When calculating the rational angle of inclination, the material from which it is decided to lay the roof is taken into account: some roofing coverings can be laid at an angle of up to 90 degrees, while others can only be laid at an angle of 15 to 60 degrees.

When choosing which slope of the planes to choose a roof for your home, you need to take into account functionality, general appearance the resulting structure (after all, you want to get an aesthetic structure) and climatic conditions. As practice shows, for European countries ideal solution you can call the angle 35-40 degrees.

Examples of calculations that are easy to do yourself

Basically, if we are talking about simple designs roof, you will need very little to calculate the height of the roof: a calculator and a few for everyone known principles from the basics of geometry, which are taught in the school curriculum.

We take the basic principle of calculation from the rule that the length of one leg is right triangle will be equal to the length of the other if multiplied by the tangent of the angle formed with the base.

• we measure the width of the building (let’s say we have a four-meter house);
• we take the angle equal to 35 degrees (as recommended best option for European latitudes);
• We calculate the tangent, it is obtained for a given angle of 0.7002;
• 4 meters * 0.7002 = 2.8 meters.

If selected gable design, then in this case the height of the ridge is also very simple to calculate: the width of the house can be divided by “two” and then multiplied by the tangent of the angle formed by the slope of the slopes. For clarity, let us consider what is described above, how to calculate the height of a gable roof using the example of a house whose width will be 10 meters . So, for the calculations:

• we take the angle equal to 35 degrees;
• We calculate the tangent, it turns out to be 0.7002;
• 10 meters/2 * 0.7002 = 3.5 meters.

The most used today are hipped structures, and to calculate them you can use the same principle (formula) as for how to calculate the height of the ridge of a gable roof, but only the width of the house is divided not by two, but by four. Plus, when making calculations for a hipped roof, it is important to take into account the length of the ridge run, as well as the rafter system.

calculation of the roof height of a four-pitched structure

The most complex calculations accompany the arrangement of the roof mansard type, characteristic feature which can be called the presence of two slopes with a break, which from the outside makes it general form as if “broken”. Arrangement sloping roof will increase the functional area of ​​the attic. Based on the calculation hip roof The example of calculating the height of a gable roof, already discussed above, is based on, but do not forget that the roof has not one angle of inclination, but several. Before moving on to settlement operations, you need to decide on them. Practice shows that it is best to choose the following angle values:

• for the lower one - over 40 degrees;
• for the rest - less than 40 degrees, but definitely more than 15.

To simplify calculations, but at the same time quickly obtain the most accurate result, experts prefer to use the “ golden ratio ", for this, in the drawing the outline of the roof is inscribed in a circle. By resorting to this successful rule, you can easily solve the problem of how to correctly calculate the height of the roof, and most importantly, avoid inaccuracies in the calculation, which in practice will lead to the fact that the overall appearance of the structure will be unaesthetic, inharmonious and simply ugly.

Where to go for help: online resource and consultants

If the roof being built is of a complex shape, then it requires more voluminous, time-consuming calculations. For calculations, data on the cross-section of the rafters, the pitch between them, and the span of the rafter structure are used. In addition, the dimensions of roof windows, chimneys, the presence of parapets and overhangs are taken into account; it will be necessary to analyze the possibility of supports and the endurance of the foundation.

Today, anyone who does not know how to calculate the height of a roof can do this by turning to assistants who can be found on the Internet. These could be specialists who are ready to provide you with such services online, or a special Internet resource called a “calculator”, in which case the site visitor enters the requested data and the system performs calculations based on them.

When choosing who to turn to for help, remember that – the design is not cheap, so it does not tolerate errors and inaccuracies. The correctness of the calculations made must be guaranteed. For beginners, calculating hip, hip and hipped roofs turn out to be quite complex, so it is better to entrust them to a design specialist with experience in this field. You can only do calculations related to single-pitch structures for outbuildings and garages, or simple gables built to cover a small country house.

Calculations of roof parameters

- This the most important stage concerning the construction of the roof. It is its result and accuracy that influences how reliable the structure will be, how long it will last, and whether it will have an attractive and harmonious appearance. There is no need to waste time and effort double-checking the results and making sure they are accurate. This is a guarantee that you will have the most durable home, designed for many years of use and providing comfort, coziness and warmth.

Accurate and correctly calculated data will help to avoid unnecessary costs for the purchase of materials, and this is reasonable savings during construction.