A simple do-it-yourself gable roof truss system. Do-it-yourself rafters for a gable roof: calculations, installation, fastening, assembly. Roofing tool kit

In any pitched roof there is a system with inclined planes (slopes). The selection and calculation of the truss system must be done taking into account the supports necessary for it, as well as the type of roof, dimensions and shapes of the structures to be covered. Having calculated the truss system of a gable roof, you can choose the right size of the rafter leg, as well as ensure the high strength of the roof.

Types and arrangement of the gable roof truss system

This system should be chosen from the conditions and the number of supports, as well as the distance between them.

For example, layered types of rafters will be supported by the load-bearing walls of structures (from the outside), as well as on additional. supports inside, if suddenly there will be more than four and a half meters between the main ones. In the lower part, the rafter leg rests on beams that transfer weight between the roof and the wall of the structure. As for the upper end, it is connected to the ridge type of run, as well as to another rafter leg.

The hanging truss system of a gable roof has a puff located at the level where the lower support nodes are located, and maybe higher than they are. There are no intermediate supports. As for the distance between the carriers from the outside, it should be up to six and a half meters. This option refers to a triangular farm, and between them the distance according to the plan is from 1.3 to 1.8 meters.

Coatings

Eternite types of roofing - fibrous or flat asbestos-cement sheets. They are cheap and easy to install.

Slate refers to slate roof options, they are made from natural materials of layered slates. Slate also includes ondulin and euroslate.

Metal coatings are used to cover residential buildings. They will reliably protect from the effects of the atmosphere, are not heavy and are easy in terms of installation work. These include aluzinc, galvanized and corrugated board.

Roll type refers to a soft roof. It has the property of not letting in moisture, and is very resistant to negative environmental influences. They are also easy to install. This includes roofing material, bito-polymer material, membrane roofing.

Some use wood roofing. But very rarely, because they are difficult in terms of installation.

Roof options that transmit light are made of glass, polymer.

We crate

It is the crate - the foundation of the roofs. It is made from beams or wooden boards. If a wooden, metal, tiled roof is being equipped, a beam is selected, the cross section of which is:

5 by 5 cm, if the distance between the rafters in the range of one meter is 1.1m).

5 by 6 cm, if the rafter pitch is from 1.2 to 1.3 meters.

6 by 6 if the step is 1.4 or 1.5 meters.

In other cases, boards can be up to 2.5 cm thick.

From wood, log options are used, which are cut down literally on one edge. In order to make layered rafters, a section of a round log with a diameter of 12 to 20 cm is more suitable.

How to calculate the desktop rafter leg?

Between the legs there can be a distance from a meter to one and a half. Their cross section must be determined in accordance with the calculations. For this, the strength and rigidity of structures are recognized. Therefore, you need to find out what is the constant load on the rafters, which includes regular loads and snow, per linear meter.

To carry out calculations, you need to know such data as:

• The step with which the rafter legs are installed
• What is the angle of the roof
• What are the dimensions of the roof

What parameters will be chosen and, in general, many coefficients, depends on the chosen material for the roof and its detailed composition.

It should be borne in mind that there must be a reliable pairing between the runs and the rafter legs. Thanks to this, the walls of structures will not be destructively torn open. If you have wooden structures, they need to be inspected periodically.

Variants of gable roofs are quite common today. But having properly equipped the roof, you will have a strong, beautiful and very durable housing!

Properly designed and assembled according to technology, the roof serves as a barrier that prevents cold air and moisture from entering the house. Outside, with the naked eye, we see only a small part of the structure - the roofing. But the roof frame, which is the most important component, performs the main supporting functions and absorbs the effects of wind and snow loads.

So that it does not deform as a result of operation, it is necessary to correctly calculate the cross-sectional value of its elements and determine the distance between them, taking into account the weight of the roofing material, slope and climatic conditions. In this article we will tell you what the gable roof truss system of a house is, what it consists of, how it is designed and assembled by hand.

The truss system for a gable roof of a house is a system of interconnected supporting elements, which together form the frame of the structure.

It is made of wood or metal in accordance with the calculation of the loads that will affect them during operation. The roof truss frame performs the following functions:

1. Gives roof slopes the necessary slope. The traditional shape in the form of an equilateral rectangle of a gable roof is given precisely by the rafter frame, which forms a slope between the base of the roof and its ridge. The angled surface allows snow and water to slide freely off the ramp.
2. Distributes the load from the weight of the roofing cake. The weight of a roofing pie, taking into account the snow load, can reach up to 500 kg / m2, so a gable roof is subjected to intense load, especially in winter. The rafters of a gable roof evenly distribute the weight that falls on them, and then transfer the load to the load-bearing walls and foundation of the house.
3. Serves as a basis for fixing thermal insulation and roofing material. The rafter frame of the roof serves as a kind of skeleton of the structure around which its “body” is built. Thermal insulation should be installed between the rafter legs, and a roofing covering is fixed on the crate, which protects against moisture penetration.

Please note that the design of the gable roof truss system is quite complicated to design and assemble, especially if the master does not have enough experience. Indeed, in order for it to be able to withstand heavy loads, it is necessary to correctly calculate the cross section of the rafters and the pitch of the rafters, taking into account the slope and length of the slopes, the roofing material used, and also draw up a drawing according to which the assembly will be performed.

Types of truss systems

Rafter systems differ in many factors, their composition depends on the layout of a wooden or brick house, the total weight of the roofing pie, the material from which the frame is made, and the type of roofing.

An important characteristic of the structure is their bearing capacity, which determines how much weight they can withstand without deformation. According to the characteristic features, the following types of truss systems are distinguished:

Layered

A rafter frame of a layered type is a frame whose rafters have 2 points of support. The upper end of the leg rests on a ridge run, mounted on vertical posts fixed to the inner wall. And with the lower end it is installed on the Mauerlat.

The assembly of a rafter system of a layered type on a gable roof is possible only if there is at least 1 load-bearing partition or capital column inside the house. This design is often called non-thrust, because the second point of support of the rafters compensates for the bursting load on the walls of the house, which is assumed by the hanging frame installation scheme.

Rafter legs of a layered type experience only a bending load, which can be eliminated by various struts. The layered truss system allows you to cover houses up to 14 meters wide.

hanging

The hanging truss system is distinguished by the fact that its rafters rest only with their lower end on a Mauerlat beam mounted on external load-bearing walls. The upper end of the rafter legs of this design does not rest on anything, but, as it were, hangs in the air, which causes 2 types of load: bending and bursting.

The bursting load of such an arrangement of elements on the outer walls is so great that it has to be compensated with the help of numerous crossbars and ties, due to which the rafter pairs are tied together.

The device of a gable roof with hanging rafters consists of triangular trusses, the rigid form of which is not subjected to loads. It is believed that the complexity of the hanging circuit is much higher.

Do-it-yourself do-it-yourself rafter system of a gable roof is mounted without difficulty, if you correctly calculate the pitch of the rafters, that is, the distance between the rafters and the size of their cross section.

Combined

Combining the best of both systems, it is recognized as the most reliable. It is used in cases where, indoors, not walls, but columns are used as a support inside the house. Then the hanging and layered rafters can be alternated to strengthen the structure with additional elements, without increasing the consumption of building materials.

Important! A sliding rafter roof is another type of frame, which differs in that the rafter legs are installed on the Mauerlat not with a rigid mount, but using a movable support. The sliding mount allows the roof to change dimensions within the power reserve during the shrinkage of a wooden house.

Design

The device of the truss system of a gable roof of any of the listed types is a combination of auxiliary and supporting elements. They evenly distribute the weight of the roofing cake, and also compensate for the bursting and bending loads that occur between them.

The cross section, length and pitch of the rafters are determined using an engineering calculation that takes into account the weight of the roofing pie, the climatic conditions in the construction region, and the slope of the structure. The composition of the truss frame of a gable roof usually includes the following elements:

1. Mauerlat. Mount the Mauerlat beam on the outer walls of the house, on which the roof slopes rest. It serves to soften the pressure on the supports and evenly distribute the load from the weight of the roofing cake. It is made of a durable beam with a section of 150x150 mm or 200x200 mm and is attached to the upper belt of the walls using anchor bolts or long metal studs.
2. Sill. This is an analogue of the Mauerlat, only it is installed on internal load-bearing walls, and vertical stands must be placed on it for mounting a ridge run.
3. rafter legs. This term refers to the elements of the frame, which are made of boards with a cross section of 150-40 mm and are installed at an angle to the base of the roof, forming the angle of inclination of the slope. What to do the distance between the rafters, their length and thickness is determined by calculation, taking into account the total load to which they are subjected during operation.
4. puff. A puff is called beams that are placed horizontally and connect the legs of one rafter pair to each other in order to reduce the bursting load on the outer walls of the structure. A crossbar is a puff installed under the very ridge of the structure.
5. Racks. A stand is a vertical beam placed on a bench to support a ridge run. It is easy to determine what distance should be between the racks, because it repeats the step of the rafters.
6. Struts. Diagonally located supports that support the rafter legs in the middle or at the bottom, preventing their deflection, are called struts.

Please note that only the calculation of temporary and permanent loads to which they will be subjected during operation can determine how to properly position the elements of the truss system. Calculating the total weight of the roofing cake helps determine the correct distance between the rafters, calculate their length and the required thickness.

The calculation of the gable roof truss system is based on the fact that in the frontal dimension it has the shape of an equilateral triangle, the sides of which can be easily calculated using simple trigonometric formulas.

These simple calculations help determine the optimal distance between the rafters, their thickness and length. The design calculation is performed in the following sequence:

• Determine the design and slope of the roof. There are various ways to choose the type and slope of the roof structure. This parameter depends on the climatic conditions and performance characteristics of the selected roofing material.
• Determine the total load on the structure. To do this, they sum up the constant loads (the weight of the roofing, their weight of the frame, thermal insulation and floors) with the temporary loads (snow load, wind load), multiply by a correction factor that takes into account the slope of the slopes, and then add 10-15% to this figure to the frame had some margin of safety.
• Calculate the length of the rafter legs. To do this, use the Pythagorean theorem, because the truss truss is an equilateral triangle. It turns out that the square of the length of the rafter leg is equal to the sum of the squares of the height of the blood and half the length of the laying. Knowing how to calculate the length of the rafters, you can calculate the height of the ridge.
• Determine the section of the elements. The optimal section of the elements is selected according to the tables in accordance with the length of the rafter legs and the distance between them. The higher these indicators, the thicker the rafter should be.

Remember that before you calculate the rafters on the roof, you need to decide on the basic design parameters. In particular, it is necessary to know exactly the height of the ridge and the slope of the roof, as well as the dimensions of the room to be covered. The result of the calculation of the roof elements should be a detailed diagram of the truss system, reflecting their dimensions and the angles between them.

We calculate the angle of inclination

The angle of inclination of the slopes is selected not depending on aesthetic preferences, but based on weather conditions, taking into account the roofing material. Steeper slopes of 40-45 degrees are built in areas with a large amount of snow cover, and more gentle slopes of 10-20 degrees in places with strong gusty winds.

Keep in mind that the steeper the slope, the higher the consumption of materials, the greater the total cost of the roof. Be sure to take into account the requirements of the material:

1. Tiles, slate require a slope of at least 22 degrees, otherwise, precipitation seeps through the joints between the elements.
2. The metal tile is laid at an angle of at least 14 degrees, as it suffers greatly from gusts of wind, it can deform or even fly off.
3. Soft roofing allows a slope angle of up to 5-10 degrees, making it possible to cover slopes of any geometry with it.
4. Ondulin is considered one of the most reliable materials and can even be used for roofs with a slope of less than 6 degrees.
5. Profiled sheets cannot be laid at an angle of less than 15 degrees, however, even slopes with an acceptable slope should be treated with a sealant for better waterproofing.

Assembly technology

Before mounting the roof frame, it is necessary to calculate the parameters of its elements, based on the calculation of the total load on the structure, and also create a detailed drawing reflecting its results.

Having a frame diagram in front of you, it is much easier to qualitatively install the gable roof truss system. The assembly technology of the structure implies the following sequence:

1. First, a Mauerlat is laid on the upper belt of the outer walls, on which the slopes will rest, and a bed is mounted on the inner partitions, if the system is layered. These elements must be firmly fixed with anchor bolts or studs.
2. Then the rafters are fastened. They are fixed with nails to the Mauerlat, and are also interconnected using a metal lining. It is worth recalling that in the rafters they make a drink under the Mauerlat beam, and not vice versa. First, the installation of rafters located on the edge is carried out in order to set the level along which the rest of the pairs will be aligned.
3. After installing the rafters, auxiliary supporting elements should be installed that will support them - struts, puffs, contractions. To more securely fix the crossbar, its end is made with a protrusion half the thickness of the beam and it is hemmed to the rafters, fixing it with nails in several places.
4. A crate is nailed over the rafter legs, on which the roofing material is fixed. The material and pitch of the lathing is selected in accordance with the characteristics of the roofing material and the slope of the roof.

Remember that a well-designed and high-quality assembled truss system is a guarantee of strength, reliability and durability of a gable roof. Therefore, do not neglect the help of professional roofers and designers when creating a roofing design for your home.

Video instruction

The truss system of any object is equivalent to the value of the load-bearing structural elements of the house. The roof plays the role of a node under which the stiffening ribs of the building are assembled. Accordingly, when installing the roof with your own hands, it is required to give the maximum value to all structural units, even when using a simple option - gable.

Advantages of gable roofs

There are a lot of options for pitched truss systems. Among them, simple symmetrical is especially popular. Why? Here are her virtues:

• On the basis of a gable roof, variations are created to reflect the special architecture of the building.
• Simple calculations, easy to understand.
• The one-piece design creates favorable conditions for the dryness of the internal space and the unhindered flow of water, snow and ice.
• The maintainability, strength and durability of a gable roof are much higher than other options.

Depending on the size, homeowners always have the opportunity to equip the under-roof space, make it a full-fledged floor or attic. In a word, a gable roof is the right and profitable solution for any object, whether it is a residential building, a summer house or a bathhouse.

Elements of the truss system

Depending on the type of roof, structural elements vary. Without knowledge of the appointments of each, it is impossible to arrange a reliable coverage at home. Let's analyze in detail:

Mauerlat

The basis of the truss system. It is a beam with a section of at least 150 mm, or an I-beam channel, if the roof structure is metal. It is located on the bearing walls of the object. Its purpose is to distribute the load of the system evenly throughout the structure of the house.

Rafter leg

Structural basic unit of the system. Together with others, it forms a truss system - strengthening the strength of the entire roof. It is made of a wooden beam, which is not inferior in cross section to Mauerlat or profile pipes.

Rafter rack

Vertical bar or pipes. Depending on the variant of the gable roof, the pillars can be located in the center and / or on the sides. They take part of the weight of the entire truss system, which is why the cross section is 150 mm.

Rafter girders

Horizontal beams laid on racks and under the ridge to support the rafter legs. They provide structural rigidity and relieve stress on trusses.

Puffs and braces

Connecting beam for rafters. The action is similar - relieving the stress of a beam or metal and making the structure rigid.

lying down

Mounting support for racks and struts. To securely connect these two elements, you need a large cross-section beam - 150 mm or a thick-walled pipe of impressive diameter.

Lathing beam

Elements laid perpendicular to the rafters. Serve to install the selected roofing and create a multilayer protective cake. The cross section is small - 40–50 mm.

If the planned roof structure is made of wooden beams, you should carefully consider the quality of the wood upon purchase - the beam should not have knots interspersed, be made of soft wood.

Also, wood must have natural moisture, otherwise it will begin to dry right in the system structure, cracking, deforming the roof model, depriving it of reliability and safety.

Calculation of the truss system

A gable roof is a complex structure. The project takes into account many factors - natural nuances, wind, constant and variable loads. It is extremely difficult to make calculations on your own, without special knowledge about the climate of the area, the characteristics of the material for the manufacture of the system, and the nuances of pressure distribution.

Ideally, the calculations are at the mercy of professionals, you can independently choose only the material for coating - the following parameter depends on its type:

Tilt angle

The minimum angle of inclination of the roof relative to the parallel of the earth is 5 degrees. However, its dependence comes from the chosen roofing material. In this capacity, traditional slate, profiled sheet, flexible and metal tiles are used.

They are guided by the following rule: the steeper the slope, the more textured the roof can be.
From 5 degrees for laying rolled protective insulation of the roof. The number of layers matters - up to 15 degrees three-layer coatings, above - two- and single-layer coatings.

• From 6 - ondulin.
• From 11 - slate.
• From 12 - corrugated board.
• From 14 to 20 - metal tiles.
• From 15 to 45 - soft roof.

Thus, the resulting precipitation - snow, water - will not linger on the surface, although complete cleaning requires one's own efforts or the involvement of specialists for the installation of the Anti-Ice system.

Determining the parameters of the rafters - step, length, section

The rarer the step, the more impressive the cross-section of the beam or the diameter of the pipes should be. As a rule, for load-bearing structures, this parameter is at least 150 mm, 100 mm - for country houses and related construction - gazebos, bathhouses, outbuildings.

Next, you need to set the number of rafters per slope: its length is divided by the installation step, which is from 60 to 100 cm + 1 extreme leg. Multiplying the result by 2 gives the total. Depending on the section of the beam, the amount of rafter legs and the installation step vary.

The length of the rafters is simply calculated if the school knowledge about the right triangle is left in the luggage. The rafter leg is equal to the hypotenuse of the resulting figure. The calculation is as follows: A² + B² = C², where - A is the height of the roof, B is half the length of the pediment, C is the length of the rafter leg. To the resulting value is always added from 30 to 70 cm for cornice overhangs.

Types of truss systems

Before getting down to work, it is important to choose a truss system option for a gable roof. There are few of them, each has its own advantages and disadvantages:

hanging

Suitable only for a standard roof width of 6 m, respectively, this is the length of the rafter leg. Fastening occurs by fixing the ends to the ridge run and the bearing wall. Be sure to install a puff that levels the stress and pressure of the structure.

In addition, they will play the role of load-bearing beams. Without them, the structure will disperse under weight. The advantages of the option are in the absolute dryness of the roof surface during the off-season, and in less deformation at the time of shrinkage.

Layered

The option is suitable for any roof width. Reliability and stability is ensured by fixing the bed to the Mauerlat. Thus, the pressure is leveled by the rack, which reduces the tension in the rafter legs. The advantage of the system is simplicity, but the design requires large investments - additional lumber is required to equip the beds.

hybrid

These systems are typical for multi-pitched roofs, where transitions are accompanied by numerous reinforcements, beams, posts, beds, slopes and other elements for the stability of the entire structure. The device is expensive and complicated, so only a professional should deal with the project and construction. At least curate it.

Do-it-yourself installation of a gable roof

So, when the option of the truss system is selected, lumber is purchased, a roof project is drawn up, you can get to work. You cannot deviate from the sequence of steps. This threatens to delay installation and loss of structural reliability.

Mauerlat mount

If the length of the beam for installing the Mauerlat is insufficient, an extension is made. Using the half-tree cutting method, the ends are connected. Additional fasteners are anchor bolts. Do not use self-tapping screws, dowels or nails - they are unreliable. Mounting to the wall is as follows:

• There must be a margin of at least 5 cm from the edge.
• Holes are drilled along the wall for inserting fasteners. Similar actions are carried out with a bar.
• Mauerlat is attached to the edge with steel studs. The fastening step is more often 2 times than the distance between the rafter legs. Subsequently, before installing the main units, they are guided by metal marks.

Important - before laying the Mauerlat, the edge of the wall is protected with waterproofing. Spread one layer even if the house is made of wood.

Making and fixing rafters

Roof trusses are convenient in that they can be assembled on the ground into a finished structure and moved to the roof. This will reduce installation time, however, the model is heavy and lifting equipment will be required, which, of course, will increase the cost of the project.

For budget construction, another method is suitable:

• At the bottom and top of the rafter legs, a gash is made to attach to the Mauerlat and the ridge run. This must be done separately with each unit, after lifting the wood up.
• Places for fixing are marked on the Mauerlat and a ridge run is installed: racks are installed along the gables, on which a beam is placed. If the length is not enough, it is increased, but in a different way, unlike the Mauerlat - a board is screwed to the junction from both sides.
• Depending on the chosen model of the truss system - layered, hanging - they make cuts in the ridge beam, Mauerlat or drill holes in them for fasteners.
• Next, begin the installation of rafter legs from opposite ends of the roof, gradually moving towards the middle. Between the corners of the extreme trusses, it is not bad to stretch the cord to exactly match the entire horizontal part.
• Between themselves, the rafter legs are connected by puffs and struts. Under the ridge part, at the angle formed by the rafters, wooden linings are stuffed, and the ends themselves are tightened with bolts.

More recently, professional builders have begun to use sliding fasteners for roof installation. Metal plates securely hold the bearing elements and at the same time move due to shrinkage. This cancels out its consequences.

The work of fixing the rafters is hard and long. You should calculate the time in advance - you can not leave the roof unfinished during the rainy season, otherwise the rigidity of the structure will be lost in the future due to absorbed moisture.

Gables and framing

The side parts of the roof - gables, are made in the form of ready-made shields from boards and are completely installed at the top. Difficulties should not arise - it is only important to carefully file them at the required angle. It is necessary to fasten the crate only after the final appearance of the roofing is known. For example:

• Under the corrugated board, the step of the crate beam will be 440 mm.
• The metal tile is fastened to the crate in increments of 350 mm.
• A soft roof needs a solid plywood coating.

It is important to note the places for the passage of the chimney - the crate should not come into contact with a brick or metal surface. The distance to the hot unit is at least 15 cm. Before installing the lathing, the finished roof is covered with waterproofing with allowances extending beyond the edges of the walls. Then the beam is mounted.

If it is decided to make a warming cake from above, then first the vapor barrier is strengthened from the inside, then the selected material is put into the boxes formed by the rafters. Next, waterproofing and wind protection.

Then it is required to re-mark the contours of the rafter legs with a bar 20 * 20 and then fill a new layer of the crate, along which the laying of the roofing material will take place - the formation of ventilation ducts. This method will save the capacity of the under-roof space if the owners are going to use it for a specific purpose.

Roofing material flooring

Regardless of the type of roofing raw material, installation starts from the edges of the roof and leads it up, laying one unit on top of the other. Thus, rain moisture will not get under the material.

The method of fastening depends on the type of material - soft tiles or tiles with a bitumen or polymer base are fused. Solid profiled sheets - ondulin, metal tiles - are fixed in pre-drilled holes to the crate, using rubber pads to seal and preserve the anti-corrosion layer.

As a result: the description of the installation of the truss system and the roof is easy only on the screen or paper. In reality, the process is complex and multifaceted. Therefore, if knowledge is not enough, it is better to invite professionals to work - their work is always guaranteed.

The calculation of the truss system should be done not after the construction of the box of the house, but even at the stage of manufacturing the building project. It must be remembered that for very responsible and prestigious buildings, it is recommended to order such work from professional architects, only they will be able to perform the correct calculations and guarantee the duration and safety of the operation of the structure.

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

Structural elements of the truss system

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

The simplest element of the truss system can be made from timber 150 × 150 mm, 200 × 200 mm or boards 50 × 150 mm and 50 × 200 mm. On small houses, it is allowed to use paired boards with a thickness of 25 mm 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 truss systems have large bursting forces, in these cases the element is calculated for stability. Accordingly, the optimal methods for fixing the Mauerlat to the walls are selected, taking into account the material of their masonry.

Bar prices

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

They are made from boards 50x100mm or 50x150mm, they can be solid or extended.

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

Puffs are calculated for stretching.

Runs

One of the most important elements of the gable roof truss system. They are calculated for maximum bending forces, they are made of boards or timber of the section corresponding to the loads. A ridge run is installed at the highest point, side rails can be mounted on the sides. Run calculations 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 against floor beams or concrete slabs, options for resting on horizontal beds 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 stops in bending.

lying down

They are laid along the attic space, rest against several load-bearing walls or interior partitions. The purpose is to simplify the manufacture of a complex truss system, the creation of new points for transferring loads from various types of stops. For beds, beams or thick boards can be used, the calculation is made according to the maximum bending moment between the support points.

crate

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

What crate is needed for corrugated board? When to mount wooden, and when metal? How to choose the right step of the crate and what factors should be taken into account?

Prices for building boards

Building boards

Stages of calculating a gable roof

All works consist of several stages, each of which has a great influence 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 lumber and the truss pitch are determined. If the loads on the rafters are very large, then vertical or angular stops are installed to evenly distribute them, the calculations are repeated taking into account new data. The direction of the impact of forces, the magnitude of torque and bending moments change. During the calculations, three types of loads should be taken into account.

1. Permanent. These loads include the weight of roofing materials, lathing, insulation layers. If the attic is in use, then the mass of all finishing materials of the inner surfaces of the walls should be taken into account. Data on roofing materials are taken from their technical characteristics. The lightest of all metal roofs, the heaviest of all are natural slate materials, ceramic or cement-sand piece tiles.

   

2. Variable loads. The most difficult to calculate efforts, especially at the present time, when the climate is changing dramatically. For calculations, data are still taken from reference books of SNiP of an outdated model. For his tables, information was used fifty years ago, since then the height of the snow cover, the strength and the prevailing direction of the wind have changed significantly. Snow loads can be several times higher than those in the tables, which has a significant impact on the reliability of 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. Data on the strength and direction of the wind are just as unreliable. Architects have found a way out of this difficult situation: data is taken from outdated tables, but a safety factor is used in each formula to ensure reliability and stability. For critical roof systems on residential buildings, the standard is 1.4. This means that all linear parameters of the system elements increase by 1.4 times, and this increases the reliability and safety of the structure operation.

   

   The actual wind load is equal to the figure 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 same formula is used to determine the maximum snow load.

   

3. individual loads. This category includes specific efforts that affect the gable roof truss system during an earthquake, tornado and other natural disasters.

The final values ​​are determined taking into account the probability of the simultaneous action of all the above loads. The dimensions of each element of the truss system are calculated using a safety factor. According to the same algorithm, not only rafter legs are designed, but also lintels, stops, stretch marks, girders and other roof elements.

A gable roof is the best DIY option for an inexperienced builder. It is simple in execution, but at the same time reliable and can withstand significant loads from both wind and precipitation. She, of course, is not very beautiful, but in the baths she looks quite organic.

To do everything consciously, it is necessary to understand the structure of a gable roof and the purpose of all its elements. Let's start in order.

Mauerlat

This is a large bar attached to the load-bearing walls around the perimeter of the building. It is this element that accounts for most of the load from the roof. And it is the Mauerlat that transfers it to the load-bearing walls.

For this element, square bars with a size of 100 * 100 mm or 150 * 150 mm are used. They are connected to the walls with embedded studs. If the bath is wooden, then the upper crown usually serves as the Mauerlat. For all other types of walls, a reinforced concrete belt is made into which studs are embedded. Then the beam of the selected section is “put on” on the studs and attracted with nuts. Sometimes it is additionally fixed with long pins.

Since the thickness of the walls is often greater than the width of the mauerlat, it can be laid with bricks from the outside of the beam. This will make the system more reliable. Only wood needs to be wrapped with two layers of roofing material - to protect it from moisture and decay.

Rafter legs and skate

A ridge is a horizontal wooden block located at the top of the roof and connecting two slopes. Rafter legs or rafters rest on it and on the Mauerlat. Since the ridge has a rather large load, it must be made of a considerable section and wood of durable species should be chosen.

The height of the roof ridge is determined based on the slope of the roof and the width of the building. The angle of the roof slope is a value that depends on climatic factors: if there is a lot of snow in winter, then you need to make the slopes steeper. They will snow well. If there are strong winds in the region, the high roof will experience heavy loads and may be damaged.

For medium conditions, the optimal roof slope angle is about 35°-45°. They will not be heavily loaded by the wind, and the snow will not accumulate much. In addition, with such an angle, you can choose any type of roofing: any of the tiles, soft roofing, slate, metal tiles.

Also remember, the higher the ridge is raised (the steeper the slopes), the larger the roof area will be. And this will lead to the fact that the cost of purchasing roofing materials and the amount of work will be large.

Knowing the slope angle and the width of your bath, you can calculate the height of the roof ridge. To do this, the width of the building must be divided by two (if the ridge is in the middle, and not shifted to one side or the other) and multiplied by the slope angle tangent (the first formula in the figure). In order not to look for the necessary coefficient in mathematical tables, it is written out and summarized in a simple table.

Multiply half the width of the house by this factor. Get the height of the ridge for your bath. For example, the width of the bath is 4 meters, the angle is 35 °. We consider: 4 m / 2 * 0.76 \u003d 1.52 m - the height of the ridge from the ceiling.

Now about the rafter legs. They are made from pine or spruce bars, or better - larch. Section 50*150 mm or 50*100 mm. The choice of bar thickness depends on:

The length of the rafter leg is also calculated according to the mathematical formula: the height of the ridge is divided by the sine of the angle of inclination (the second formula in the figure). The sines of the tilt angles are also in the table. Find the right value and count. For example, for the ridge we found is 1.52 m and the angle of inclination is 35 °, the rafters will need 1.52 m / 0.57 = 2.67 m.

Roof overhang and filly

But the roof does not end exactly above the load-bearing wall. It extends beyond the walls by about 40 cm. This ledge is called the roof overhang. This is done so that the water flows further from the foundation, does not wash it away. Therefore, the rafter legs are taken longer. If their length is not enough, they are grown with boards, which are called "fillies".

Types of truss systems

Rafter systems come with hanging or layered rafter legs. The hanging ones rest only on the outer walls of the building (on the Mauerlat or the upper crown). In order to increase the reliability of the system, so as not to ruin the walls, they are connected by puffs (also called a jumper or crossbar). This type of rafter system is suitable for buildings of small width (less than 10 m) and in cases where there is no load-bearing wall running in the middle.

The second type of system is with layered rafters. They rest on a ridge beam and a mauerlat, but the load from the roof is also distributed to the middle load-bearing wall, through vertical bars - girders, which are installed with the same pitch as the rafters and rely on the lower puff.

Do-it-yourself installation of gable roof rafters

For most of the baths, the system is made with hanging rafter legs - the dimensions allow this. In this case, less consumption of lumber and less time is required for its arrangement. In this case, most of the work can be transferred to the ground.

They make one triangle from the rafters according to all the rules and sizes. They try it on, and then make the right amount of its exact copies. Finished rafters with puffs and crossbars, fastened and measured, are raised to the roof. There they are set strictly vertically in the designated places and are fixed to the Mauerlat and the ridge.

An example of how to make a gable roof with hanging rafters, see the video.

With a roof slope length of more than 4.5 meters, to increase the reliability of the system, vertical racks are installed, which support the rafter leg at one end, and rest against the floor beam with the other. This is done regardless of the type of installation of rafters: both hanging and layered. They also install slopes that make the structure even more rigid.

In any case, the rafters will need to be attached to the ridge beam, as well as to the Mauerlat. The figure below shows the mounting options for the ridge.

It will also be necessary to attach the rafters to the Mauerlat. How to do this - see the photo below.

Lathing device

Making a gable roof with your own hands ends with the installation of a crate for roofing material. To do this, a waterproofing film or membrane is rolled out on the outside of the rafters. Lay it in a horizontal direction. Starting from the bottom, moving up. The second and all subsequent rows are laid with an overlap of at least 15-20 cm. They are fixed with small nails or staples from a staple gun.

There are two ways - with or without a counter-crate. The counter-lattice is stuffed along the rafters, and on top there are already lathing bars. Thus, an air gap is formed between the waterproofing and the roofing material. This option is better from the point of view that such a roof will dry out better and faster. And this is very important for baths.

Without a counter-lattice, the bars are packed immediately over the waterproofing. There is also a gap here, but it is smaller, therefore, ventilation will be worse. But this option is also acceptable: less consumption of materials and work, too.

After the manufacture of the crate, it remains only to fix the selected roofing material.

Results

Now you know how to make a gable roof with your own hands. Of all types, this is the simplest option that a non-specialist can make.