How to calculate the height of the roof - how to calculate the correct height of the ridge of a gable roof. Calculator for calculating a gable roof Height of a gable ridge

The construction of a private house is completed with the construction of a roof. This is an especially important stage, since the reliability of the structure depends on the competent implementation of this process. The construction process itself can be conditionally divided into several stages, from the installation of the Mauerlat to the installation of the roof covering.

When installing the roofing material on the slopes at the point of their convergence in the uppermost part of the roof, as a rule, gaps are formed. Therefore, an element is needed that, on the one hand, will protect the under-roof space from the penetration of precipitation and melt water, and on the other, it will provide ventilation of the roof. This is the so-called ridge on the roof (photo below).

This element is defined as follows. The ridge of the roof of the house is the upper edge located horizontally at the junction of the slopes. It also includes those associated with this rib. Thus, it is a prefabricated structure consisting of a collection of several fragments. Installing a ridge on a roof requires a little theoretical training and basic building skills, that is, in fact, everyone can cope with this task.

Types of ridge construction

The ridge on the roof is formed by closing the planes of the slopes. It has two versions and depends on.
- A beam that is installed on vertical posts, resting on puffs either on the ceiling beams, or fixed on the gables. It supports the top of the rafters.
- A run (base of the ridge), laid at the top of rigid triangular trusses set one after another, made of rafter legs connected in pairs, which are interconnected by jumpers. A roof ridge log with a wide cross-section or two 5 cm thick boards sewn at an angle can act as a run.
From all this it follows that first of all we are dealing with a gable roof component. However, it can also be found in structures with a more complex configuration. For example, or, in which it is biased.

Relatively recently, asbestos cement was used to decorate the ridge; today, manufacturers often offer a galvanized roof ridge. Galvanized dimensions are usually standard: their length is about two meters, and the width of the shelves is 25-30 cm.

At the place of installation, there are three main options for the ridge:
- straight, which has become a gable roof. It is level-installed strictly horizontally;
- mortise, which cut into the inner joints of the roof slopes, below the main one;
- intersected, suitable for installation on multi-slope structures in places where planes cut into the main roof intersect.
How to calculate the height of the ridge of a gable roof

The desired value depends on several factors, but, as a rule, the type of attic is considered the determining one.

In the general case, the slope of the slope and the dimensions of the structure and, as a derivative, the type of material are taken into account. The calculations use data from a specially developed table, in which the width of the structure and the slope are related through the coefficient.

Let's say the width of the building is 8 m and the slope is 40 °. The height of the ridge of a gable roof is calculated according to the following scheme: half the width is multiplied by a coefficient, the value of which is found from the table. Thus, the height or distance between the top of the roof ridge and the ceiling is 4x 0.86 = 3.44.

Chimney height relative to the roof ridge SNiP

There is an opinion that regarding the ridge of the roof, it is determined solely by the desire of the homeowner and the exterior of the house. However, it is not. In fact, the efficiency of heating equipment, and the high-quality removal of combustion products, and the level of energy consumption depend on it.

A competent calculation of this parameter is based on
- at the location of the pipe in relation to the ridge;
- slope of the slopes;
- the presence of objects or trees near the house that are higher than it;
- intensity of wind and snow loads typical for a given area.
We give the optimal values of the required quantity for some structures:
- Flat roof. Regardless of the section, the height of the pipe must be more than half a meter.
- Pitched roof. Let L = distance from the ridge bar. At
- L = 1.50 m, the height of the pipe cannot be 50 cm of a purlin or a guardrail by more than 50 cm;
- 1.5 < L< 3 м, труба предполагается выше этих элементов;
- L> 3 m, then the parameter is determined by an imaginary line that is 10 ◦ with the horizon line.
How to do it yourself

The run is made of steel or wood. When building private houses, the second option is mainly used, since steel ones are rather heavy.
- The installation is carried out after completing the main stages of the roofing device. The basic principle of laying the ridge trim elements is in laying the extreme fragments from the side of the gables, through which the mounting cord is pulled. The lace is leveled and temporarily fixed to opposite gables. It will serve as a guide for the rest of the fragments.
- It is recommended to carry out the work together. After installing and fixing the first structural element, proceed to the next one. Fragments are laid with a spacing of about 20 cm, which makes it possible to achieve better waterproofing of the structure. In the same way, all elements are laid and fixed along the slope.
Attention!
Particular attention must be paid to the fastening of the edge elements, since they are under the influence of maximum wind loads.
- However, just one fit, even if the shelf width is more than 20 cm, is not enough to provide sufficient waterproofing. In any case, there will be cracks through which drops of rain or snow blown by the wind can get under the roof. You can put a layer of glass wool in the groove, but try not to seal it too much, as this may interfere with ventilation.
- There is another way: instead of glass wool, use a self-adhesive foam tape (filler), which is laid along the edge of the shelf from the bottom side. But this material is quite expensive, and the result obtained is similar to the option using glass wool.
- A ventilation compartment must be provided without fail. Otherwise, the accumulation of condensation cannot be avoided, even if the roof has been reliably protected from moisture.
On a note
If, due to the peculiarities of the roofing structure, it is not possible to equip it or at least provide the required gap, then to combat attic dampness, windows are installed in the end parts.

How to fix the ridge to the roof: from corrugated board, on slate

The fastening method depends entirely on the material of the protective strip. Curly elements are often made of the same.

A mandatory procedure is the waterproofing of wooden roofing elements. Before starting the installation of finishing elements, the girder is covered with roofing tape.
- ... Let's take a closer look at how to install a ridge on a corrugated roof.
- The roofing device assumes that there is a gap of about 5 cm between the covering and the top in the area of the ridge, which provides ventilation. In the same area parallel to the axis on both sides of the roof, lathing bars are additionally mounted.

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The calculation of the rafter system should not be done after the construction of the house box, but even at the stage of manufacturing the building project. It must be remembered that for very important and prestigious structures, such works are recommended to be ordered by professional architects, only they will be able to perform the correct calculations and guarantee the duration and safety of the structure's operation.

Although this is one of the simplest types of systems for residential buildings, there are several types of construction. The variety allows you to increase the options for the use of roofs in the construction of houses according to standard or individual exclusive projects.

Gable roof truss system type	Architectural features and short description
	The most commonly used option has two completely identical rectangular slopes. The loads between the individual elements are distributed evenly, regardless of their location. The number of additional stops is not limited, the specific decision is made depending on the plans for the use of the attic space. Calculations can be done using free programs posted on construction sites.
	The ridge is displaced to one side of the house or slopes with different angles of inclination. A more complex roof rafter system for calculations. If, in a simplified version, one slope can be calculated and the obtained data is automatically applied for the second, then this option cannot be used for an asymmetric rafter system. Advantages - original appearance. Disadvantages - the complexity of calculations and installation and a decrease in the used attic space.
	It is most often used during the construction of attic rooms, it allows you to significantly increase the volume of attic rooms. Difficulty calculations are in the middle category. Rafter system with an external break. Systems with an internal break are rare, apart from the original appearance, they have no advantages.

Structural elements of the rafter system

We will give a list of all the elements that need to be calculated for each specific case.

The simplest element of the rafter system can be made from a bar of 150 × 150 mm, 200 × 200 mm or boards of 50 × 150 mm and 50 × 200 mm. On small houses it is allowed to use paired boards with a thickness of 25mm or more. Mauerlat is considered an irresponsible element, its task is only to evenly distribute point forces from the rafter legs along the perimeter of the facade walls of the building. It is fixed to the wall on a reinforcing belt using anchors or large dowels. Some rafter systems have large spreading forces, in these cases, the element is calculated for stability. Accordingly, the optimal ways of fixing the Mauerlat to the walls are selected, taking into account the material of their masonry.

Timber prices

They form the silhouette of the rafter system and perceive all acting loads: from wind and snow, dynamic and static, permanent and temporary.

They are made of boards 50 × 100 mm or 50 × 150 mm, they can be solid or extended.

Boards are calculated according to bending resistance, taking into account the data obtained, species and types of wood, the distance between the legs, additional elements to increase stability are selected. The two legs connected together are called a truss, and they can have puffs in the upper part.

Tightens are calculated in tension.

Runs

One of the most important elements of a gable roof rafter system. Designed for maximum bending forces, made of planks or beams corresponding to the load section. A ridge girder is installed in the highest place, side ones can be mounted on the sides. The calculations of the runs are quite complex and must take into account a large number of factors.

They can be vertical and inclined. Inclined work in compression, attached at right angles to the rafters. The lower part rests on floor beams or concrete slabs; options for resting on horizontal benches are acceptable. Due to the stops, it is possible to use thinner lumber for the manufacture of rafter legs. Vertical stops work in compression, horizontal ones in bending.

Beds

Stacked along the attic, abut against several load-bearing walls or interior partitions. Purpose - to simplify the manufacture of a complex rafter system, the creation of new points of transfer of loads from various types of stops. For the bed, you can use beams or thick boards, the calculation is done according to the maximum bending moment between the support points.

Lathing

The type of lathing is selected taking into account the technical parameters of the roofing and does not affect the performance of the rafter system.

What kind of lathing is needed for corrugated boarding? When to mount wood and when metal? How to choose the right lathing pitch and what factors should be taken into account?

Construction boards prices

Construction boards

Stages of calculating a gable roof

All work consists of several stages, each having a great impact on the stability and durability of the structure.

Calculation of the parameters of the rafter legs

Based on the data obtained, the linear parameters of the lumber and the pitch of the trusses are determined. If the loads on the rafters are very large, then for their even distribution, vertical or corner stops are installed, the calculations are repeated taking into account the new data. The direction of the action of the forces, the magnitude of the twisting and bending moments, changes. During the calculations, three types of loads must be taken into account.

Permanent. These loads include the weight of roofing materials, battens, insulation layers. If the attic space is exploited, then the mass of all coating materials of the inner surfaces of the walls should be taken into account. The data on roofing materials are taken from their technical characteristics. The lightest of all metal roofs, the heaviest of all natural slate materials, ceramic or cement-sand piece tiles.
Variable loads. The hardest effort to calculate, especially at a time when the climate is changing dramatically. For calculations, data are still taken from the SNiP reference books of the outdated sample. For his tables, information from fifty years ago was used, since then the height of the snow cover, the strength and the prevailing direction of the wind have changed significantly. Snow loads can be many times higher than those in the tables, which has a significant impact on the reliability of the calculations.

Moreover, the height of the snow changes not only taking into account the climatic zone, but also depending on the location of the house on the cardinal points, the terrain, the specific location of the building, etc. The data on the strength and direction of the wind are also unreliable. The architects have found a way out of this difficult situation: the data are taken from old tables, but to insure reliability and stability, a safety factor is used in each formula. For critical truss systems on residential buildings, the standard is 1.4. This means that all the linear parameters of the elements of the system increase by 1.4 times, and due to this, the reliability and safety of the structure is increased.

The actual wind load is equal to the indicator in the region where the building is located, multiplied by the correction factor. The correction factor characterizes the features of the location of the building. The maximum snow load is determined using the same formula.
Individual loads. This category includes specific efforts that affect the rafter system of a gable roof during an earthquake, tornado and other natural disasters.

The final values are determined taking into account the likelihood of the simultaneous action of all of the above loads. The dimensions of each element of the rafter system are calculated using a safety factor. Using the same algorithm, not only rafter legs are designed, but also jumpers, stops, stretch marks, purlins and other roof elements.

The process of selecting the best parameters for a gable roof is always a search for a compromise between the desired shape of the frame, the desire to obtain a beautiful high structure and the requirements for ensuring the strength and stability of the roof. In addition, the size of the gable roof will have to be tied to the weather "tricks" of the local climate and their own financial capabilities.

What determines the height of the ridge of a gable roof

To obtain a durable and beautiful structure, first of all, it is necessary to choose the optimal angle of inclination of the gable roof. This is a basic parameter, it must be selected based on the following criteria:

The strength of the rafter system, the higher the angle, the less load on the frame from snow, precipitation is removed faster and more efficiently;
The presence of strong winds, the correct angle helps to reduce the pressure on the roof slope;
The height and dimensions of the attic space. The larger the volume of the air cushion in the attic, the warmer the gable roof will turn out. If you correctly calculate and plan the height of the ridge beam, the attic can well be turned into an additional living room.

Important! In addition to the listed conditions, it is necessary to take into account the weight of the structure, the longer the rafters and overhangs of a gable roof, the greater its weight, which loads the walls of the house, and the higher the cost of construction.

What is the angle for a gable roof is the optimal ridge height

In contrast to the design process, in direct construction it is rather difficult to work with angular values. To directly determine and accurately set the slope of the slope, you need an accurate measuring technique. Instead of the angle of inclination of the rafter beams, it is easier to use linear quantities, for example, the length of the rafters, the size of the span or the height of the ridge. In this case, the desired angle of inclination can be easily calculated using trigonometric formulas by measuring the height of the ridge and the distance between the rafter supports on the Mauerlat.

Climatic and technological restrictions on the height of the ridge of a gable roof

For areas where the main factor is open space, respectively, strong wind loads, the height of the ridge is most often calculated based on the recommendations of the manufacturer of the roofing material.

In such conditions, the main factor determining the stability of a gable roof is the wind load. Rainwater and sleet do not pose a particular threat due to the sweeping effect of horizontal air currents, so there is no need to increase the angle of inclination of the roof structure. Moreover, with a considerable height of the ridge, the windage of the gable roof and the pressure on the walls of the building sharply increase.

Experts do not recommend reducing the height of the ridge beam to a minimum. Firstly, it significantly reduces the thermal insulation properties of the gable roof and reduces the amount of usable space in the attic.

Secondly, the roof with a reduced ridge height is no longer pressed by the air currents against the building box, but tend to overturn or tear it off from the supporting surface. This situation is much worse than the situation with windage, since the gable roof is not designed for excessive internal pressure. Thirdly, certain types of roofing material cannot be laid on roof slopes with an extremely low ridge height. If such a situation arises, it is better to seek advice from specialists in a specific type of roofing material, who will help to calculate the safety factor and the method of installation.

If a large amount of precipitation is recorded on the ground in the form of wet snow, the height of the ridge of the gable roof and, accordingly, the steepness of the slopes is calculated according to the following scheme:

The maximum amount of wet snow that has fallen in a given area over the past decades is determined;
Based on the future dimensions of the house box and financial capabilities, determine the maximum size of the rafters and the load-bearing capacity of the roof frame with the specified thickness of the snow cover. The number of rafters, lifting height and pitch are calculated based on the methodology outlined in SNiP 2.01.85 "Loads and Impacts";
If the size of the timber for the rafters turns out to be prohibitively large, it is necessary to increase the height of the ridge, but so that the angle of inclination of the gable roof does not exceed the optimal values for the selected roofing material.

When calculating the load on the rafters, it is assumed that with a ridge height that provides an angle of inclination of more than 60 °, the weight of the snow mass on the surface of the gable roof can be ignored. When the ratio of the ridge height above the Mauerlat horizon to the distance between the lower supports of the rafters is less than ¼, the snow pressure on the roof is taken into account in full. In an intermediate position, with an increase in the angle of inclination of the gable roof from 20 ° to 60 °, the correction reduction factor changes monotonically from 0.7 to 0.1.

Optimal gable roof ridge height

Often, the decision to increase the height of the ridge is made not to reduce the load on the roof, but to increase the usable space of the attic. The benefits of such a modification, at first glance, are obvious. You can increase the amount of usable space and equip, for example, an attic and even a balcony. It is relatively easy to assess changes in the shape and size of the under-roof space using the diagram shown in the figure.

Before making a decision, try to calculate the geometry of the consequences of the increased skate height. Consider, as an example, the change in the characteristics of the height and dimensions of a gable roof for the smallest building measuring 6x4m and a wall height of 2.5m. A sketch of the roof structure is shown in the figure.

With the optimal height of the ridge above the floor slab of 2 m, the length of the rafter beam will be 2.9 m. In this case, the usable space under the gable roof will be only 4x1.8x0.5 m. This is enough for ventilation and roof insulation work. The width of the usable space, if desired, can be increased to 1.5 m. On this area, you can organize a bedroom or a rest room, for which, in fact, the attic is used.

An angle of inclination of 45 ° with a ridge height of 2 m ensures optimal structural strength, if you choose the right material and calculate the beam consumption for the construction of rafters, you can get a very moderate cost of the rafter system, primarily due to the absence of struts and struts.

You can try to increase the width of the attic comfort zone from 0.5 m to 1.5 m. In this case, the height of the ridge and the angle of inclination of the gable roof will increase to 3.6 m and 60 o, respectively. The space available for use has increased from 1.5 m to 2.5 m, the comfort zone, or the area within which you can walk without bending, is 1.5 m, which is quite consistent with the average parameters of the attic for a country house.

The length of the rafters has increased from 2.9 m to 4.2 m. It is assumed that the cost of the timber for the gable roof frame will increase by 30% due to the need to install additional load-bearing elements - beams and struts. If the loads and the method of fastening are correctly calculated, the structure will be as strong as in the previous version.

Alternative option

Even a cursory comparison of the two options, without trying to calculate the exact characteristics, allows us to draw certain conclusions.

The size of the usable area of the attic in a broken roof version is larger than that of a two-slope scheme with an increased ridge height by 15%, the amount of timber and roofing materials was spent more by 19% and 7%, respectively. The cost of work for a broken circuit is 30-33% higher. The gable roof structure is 0.8 m higher, but at the same time the center of gravity of the frame is below the center of pressure, which allows it to be more stable in strong winds, despite the fact that the angle of inclination of the rafters is 60 o higher than the angle of the upper row of the sloping roof.

In addition, large air "bags" above the ceiling and in the side walls of the duplex version of the attic insulate and soundproof the room well. For a long stay in the attic room, a broken pattern is more suitable due to the increased comfort. Whereas for a country house or a bath, it is quite realistic to use the design of a classic gable roof with an increased height of the ridge beam.

The given comparison is valid only for small-sized gable and broken circuits. As the size of the house increases, the gable version of the roof with an increased height of the ridge beam becomes much more expensive than the cost of a similar-sized broken pattern.

Conclusion

It should be noted that the calculation of the required ridge height greatly depends on the type of roofing material. The vast majority of roofing materials, from tiles to ondulin, fit perfectly on a slope with an angle of inclination of 60 °. Due to the fact that the roof slope is a single plane, the laid roof has a significantly higher resistance to any form of precipitation. Broken structures often suffer from rainwater leaks during heavy rain and wind precisely on the break line.

The roof is an important structural part of the house, performing a number of the most important functions. It protects from atmospheric attacks and removes precipitation, provides insulation and makes a solid contribution to the formation of your own building style. In order for such a significant structure to cope with the entrusted work perfectly, it is necessary to thoroughly think over the project and scrupulously deal with the dimensions.

A careful analysis and calculation of a gable roof is required both for independent craftsmen and owners of suburban property who use the services of construction organizations. Let's figure out how to do it right.

The roof, which resembles an inverted V in section, is leading in the list of pitched structures for a reason. In terms of simplicity of construction and economy, the gable roof has practically no rivals. For centuries, proven in practice, laid the foundation for the construction of most roofing structures.

Unpretentious pitched planes do not require complex cutting of the coating and other materials, which results in an impressive amount of waste. No specific tricks are needed to implement intricate configurations. Precipitation does not linger on inclined surfaces, so there is no need to reinforce waterproofing. As a result, the device of a gable roof is often cheaper than a gable 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 awnings over the entrance porch, i.e. there are no additional fractures, ridges and associated valleys.

The absence of convex and concave corners deprives the master of "pleasure" to suffer with a number of difficult operations. Again, the owners will not get the imaginary pleasure of the leaks that often appear at the joints of the pitched roof elements.

In principle, no one bothers lovers of fancy architecture to equip two ramps with numerous built-in structures. True, there are restrictions on climatic characteristics: in areas with a high volume of winter precipitation, the construction of roofs with numerous components is undesirable. In the gutters formed by excesses, favorable conditions are created for the accumulation of snow deposits. They will have to be cleaned faster than usual, and excessive diligence in the field of snow removal can cause damage to the coating with all the consequences.

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

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

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

An impeccably designed roof has perfect proportions. Its width and height determine the rise and slope required to drain precipitation in a particular area. The lower is impossible for technical reasons, the higher is expensive and unreasonable if the unique architecture does not require it.

Note that as the steepness increases, the building budget goes up. Roofing material is selected according to the slope. Focusing on its weight and specificity, the rafter frame is designed and calculated. 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 structure of the rafter frame and the nuances of the selection of the coating makes it necessary to determine the best shape by means of a banal selection. If something does not fit, the supporting structures are replaced or reinforced. Fortunately, the assortment on the construction market is now plentiful, and all kinds of methods have been developed to strengthen the structure.

If the upcoming calculations and data shuffling are intimidating, it is better to resort to a win-win solution - a sample project. It is not for nothing that abroad all houses of one settlement are equipped with roofs of equal height and covered with materials of equal color and characteristics. Typification allows you to maintain landscape identity and reduce design costs.

However, even a typical design solution is not a panacea for technical troubles and aesthetic shortcomings. We must not forget about the individual dimensions of the box, over which it is planned to erect a roof. Compatriots deny the equalization in height and steepness, therefore it is still desirable for us to deal with the proportions of the roofing structure.

Step-by-step calculations

The configuration and dimensions of any pitched roof is set by the rafter frame. Slopes are laid on the edges of the rafter legs, forming a dihedral angle. Rafter systems are built from rolled metal and wood, industrial structures and lumber are used in construction.

Let's take a look at the options available to apply the efforts of a do-it-yourself wizard, i.e. construction method for erecting a roof frame made of 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 structure of the structures, it will be difficult to understand the geometric parameters.

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

Naslonnaya, according to which the top and bottom of the rafters have a strong fulcrum. The walls of the house, equipped with a Mauerlat, serve as the lower support. The top of the layered rafter legs rests on the girder that forms the ridge. The running beam is supported on a support system built specifically for it, on an internal wall or on stone gables of the box, erected before the roof device. The nesting method is mainly used when arranging large houses with an internal load-bearing wall or a row of columns.
Hanging, according to which the rafters tops rest only against each other. The walls serve as a support for the bottom, as in the previous case. Hanging rafter legs form an equilateral triangle, the base of which is called a puff. Taken together, such a system does not create a thrust, i.e. does not transfer the bursting load to the box walls. The rafter triangles are either installed ready-to-install, i.e. assembled on the ground, or constructed from separate 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 of structural elements when overlapping boxes up to 8-10m wide.

When arranging spans larger, there is a risk of deformation of the rafter legs. In order to exclude sagging and deflection of wooden parts from lumber, reinforcing elements are installed: struts, contractions, side girders, etc.

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

Stage # 2 - calculating the width

Both types of timber truss systems are constructed over floor beams or over Mauerlat. How the roof width is calculated depends on the type of base:

When mounted on floor beams, it is they who form the eaves overhang, i.e. determine the dimensions of the roof.
When installed on a Mauerlat, the roof width 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, in the calculations, only the load-bearing part of the roof width is used, which is equal to the width of the box.

The function of the Mauerlat in frame buildings is performed by the upper strapping, at the same time connecting the disparate elements into a single frame. In wooden construction, the upper crown, folded with a bar or log, serves as a mauerlat.

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

Eaves overhangs of roofs installed on a Mauerlat can be formed directly by rafter legs sewn to them by fillets or a brick ledge. The latter option, of course, is used in the construction of brick walls. The choice of overhang width is dictated by the type of roofing and the material from which the walls are folded.

For slate roofs no more than 10cm;
For bituminous 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 beams require enhanced protection from slanting rains, so the overhangs above them are usually increased by 10-15cm. If the maximum value of the overhang width recommended by the manufacturer is exceeded, measures must be taken to strengthen it.

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

Stage # 3 - defining the slope

The angle of inclination of the slopes is allowed to vary in the widest range, 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 asymmetric structures for residential buildings, they are mainly placed at an 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 way the base is arranged for its fastening. The denser the roof is, the lower the slope can be. The fewer overlaps and joints between the elements of the covering, the lower the roof is allowed to be. And vice versa.
Roof weight 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 rapid removal of snow and water, which is highly desirable in areas with significant rainfall. 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 shallow structures, and in areas with abundant precipitation, roofs with a high slope.

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

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

Stage # 4 - determining the height of the skate

A roof with two slopes may or may not have an attic at the request of the owner. In the attic spaces of gable roofs, it is not supposed to arrange useful premises. For this there is. However, the height of the attic used for maintenance and inspection of roofs from an angle is not arbitrary.

According to the requirements of the fire service, the distance from the top to the overlap must be at least 1.6 m. The upper limit is dictated by the aesthetic beliefs of the designers. They argue 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 hanging roofs arranged on beams is easiest to determine by the drawing method:

We draw a diagram of the box of the house to scale.
We are looking for the middle of the upper floor.
From the middle up, we lay the axis of symmetry.
On either side from the middle, set aside half the width of the roof - we get the extreme point of the overhang.
Using a protractor from the extreme point of the overhang, draw a straight line at an angle recommended by the manufacturer of the roofing. Its point of intersection with the axis will be the top of the roof. Let's measure the distance from the top to the overlap and get the height.

To get a complete picture, you need to draw a second ramp 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 configuration of the roof, you can play with the height on paper by 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 should be taken into account. With impressive power, it will slightly shift the position of the slopes.

Craftsmen believe that the 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 run. This is the most loaded element, all others have the right to be thinner. For example, if calculations show that a material of 100 × 150mm is required for a ridge run, then a board of 50 × 150mm is enough for rafters, supports, struts.

The process of finding the height of structures with overhangs formed by filly differs little from the described method. 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 rafters to the Mauerlat. In any case, it is better to pick up variations with the steepness and dimensions of the gable roof planned for construction on "paper" than on the construction site.

Stage # 5 - calculation of material consumption

A normal owner thinks ahead of time about the construction budget. True, in the preliminary estimate, by definition, there will be 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 amount of basic expenses.

The preliminary estimate should include:

A bar for the device Mauerlat. In housing construction, lumber is used with a cross section from 100 × 150mm to 200 × 200mm. The footage is calculated around the perimeter of the box with a 5% margin for processing and joining. A similar material is purchased for the bed device, if it is designed.
Board for the manufacture of rafters. Most often, for the manufacture of rafter legs, a 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 number. The material is purchased with a margin of 15-20%.
A board or bar for making struts, braces and supports with a section of 50 × 100, 100 × 100mm, depending on the project. You also need a stock of about 10%.
Material for the lathing device. Its consumption depends on the type of topcoat. The lathing is erected either solid, if it will be produced, or sparse for corrugated board, metal roofing, ordinary tiles, slate, etc.
Roll waterproofing, the footage of which determines the type of roof and the steepness. High roofs are covered with a waterproof carpet only along the eaves, ridge and in convex or concave corners. Gentle ones are covered with a solid carpet.
Finish coating. Its amount is calculated by summing the areas of the rays. If there are embedded dormer windows, then their areas are also counted. Only calculated as a rectangle, not after the fact. The amount of stock for laying is recommended by the coating manufacturer.
Material for covering gables and overhangs.
Corners, plates, screws, staples, nails. Anchors and studs are needed, their number will tell the project.

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

The online gable roof calculator will help you calculate the rafter tilt angles, the required amount of lathing, the maximum roof load, as well as the materials required for the construction of this type of roof at the given dimensions. You can calculate the roof from such popular roofing materials as slate, ondulin, ceramic, cement-sand and bituminous tiles, metal tiles and other materials.

The calculations take into account the parameters given in TCP 45-5.05-146-2009 and SNiP "Loads and Impacts".

A gable roof (also known as a gable or gable roof) is a type of roof that has two sloping ramps that run from the ridge to the outer walls of the building. This is the most common roof type today. This is explained by its practicality, low construction costs, effective protection of premises and an aesthetic appearance.

The rafters in the gable roof structure rest on each other, connecting in pairs. On the front side, gable roofs are in the shape of a triangle, such ends are called tongs or gables. Usually, an attic is arranged under such a roof, which is illuminated with the help of small windows on the gables (attic windows).

When entering data into the calculator, be sure to check the additional information marked with the icon.

At the bottom of this page, you can leave feedback, ask your own question to the developers, or suggest an idea for improving this calculator.

Explanation of calculation results

Roof angle

The rafters and roof slope are inclined at this angle. It is understood that a symmetrical gable roof is planned. In addition to calculating the angle, the calculator will inform you how the angle corresponds to the norms for the roofing material you have chosen. If you need to change the angle, then for this you need to change the width of the base or the height of the roof rise, or choose another (lighter) roofing material.

Roof surface area

The total area of the roof (including overhangs of a given length). Determines the amount of roofing and insulation materials that will be needed for the job.

Approximate weight of roofing material

The total weight of the roofing material required to fully cover the roof area.

Number of overlapped rolls of insulation

The total amount of insulating material in rolls that will be required to insulate the roof. The calculations are based on rolls 15 meters long and 1 meter wide.

Maximum load on the rafter system. The calculations take into account the weight of the entire roofing system, the shape of the roof, as well as the wind and snow loads of the region you specified.

Rafter length

The full length of the rafters from the beginning of the ramp to the ridge of the roof.

Number of rafters

The total number of rafters required to build a roof at a given pitch.

Minimum cross-section of rafters, Weight and Volume of timber for rafters

The table shows the recommended cross-sectional dimensions of the rafters (according to GOST 24454-80 Softwood lumber). To determine compliance, the type of roofing material, the area and shape of the roof structure, as well as the loads exerted on the roof are taken into account. The adjacent columns show the total weight and volume of these rafters for the entire roof.

Number of rows of crate

The total number of battens for the entire roof. To determine the number of rows of crate for one slope, it is enough to divide the resulting value by two.

Uniform distance between battens

Use the value shown here to install the battens evenly and avoid unnecessary overruns.

Number of battens in standard length

To frame the entire roof, you will need the number of planks shown here. The calculation uses the standard 6-meter board length.

The volume of lathing boards

The volume of boards in cubic meters will help you calculate the cost of the crate costs.

Approximate weight of crate boards

Estimated total weight of the sheathing boards. The calculations are based on the average density and moisture values for softwoods.