Rafter system gable roof designed for constructing a roof in the form of two rectangles located at a certain angle to each other in the upper part of the structure. This design is quite often used in the construction of private low-rise buildings and various buildings for domestic and commercial purposes. In industrial and commercial enterprises, a gable roof is installed on buildings for various purposes that have a significant length, several times greater than the width. The design contains two slopes of different lengths. A short slope with a large angle of inclination is installed on the front side, and a long one with a smaller angle of inclination on the rear side. This configuration allows the bulk of atmospheric precipitation to be directed to the non-working area of ​​the enterprise territory.

Figure 1. Diagram of fillies.

Construction of a gable roof is one of the low-cost options and does not require significant physical effort.

It is relatively simple to perform if you have a little experience working with wood materials.

Typical load-bearing elements of the system, specific terms

Figure 2. Sheathing diagram.

In the manufacture of parts of the gable roof rafter system, softwood lumber is used. It is undesirable to use hardwood due to its high specific gravity. Most elements have specific names that are understandable mainly to specialists:

1. Lezhen - timber with a section of 150x150 mm, 180x180 mm. Placed on the surface of the internal load-bearing wall. Designed to level the surface and distribute loads from the racks.
2. A rafter leg, or rafter, is a piece made of timber or thick boards. The main element of a triangular roof structure, bearing the main load from snow, rain, wind and other atmospheric phenomena. The distance between the rafter legs can be from 0.6 to 1.2 m. The pitch size mainly depends on the plumb line of the roofing material; in some cases, the characteristics of the roofing material should be taken into account.
3. Mauerlat is a square beam with a side size of 150-180 cm. It is laid on the surface of external load-bearing walls. When installing, it must be secured using anchor bolts or other reliable means. Distributes the load from the rafter legs to load-bearing walls.

All parts of a gable roof are connected to each other in different ways. Previously, structures were assembled mainly using staples, nails, and threaded rods. Now manufacturers of building materials offer a wide range of different brackets for assembling roofs of any configuration. Most parts are fastened with self-tapping screws of the required diameter and length, reinforced with special tenons in the brackets.

Return to contents

Additional elements of the rafter system

Figure 3. Diagram of an arch with three hinges.

In addition to load-bearing parts, additional reinforcing elements are used in structures:

1. Fillies (Fig. 1) - used to increase the length of the rafter legs. Installed in the lower part for the installation of eaves overhang. The thickness of the fillies is several smaller sizes rafters
2. A roof overhang, or eaves overhang, is a roof element that protrudes beyond the edge of the wall by about 40-50 cm. Designed to protect walls from precipitation.
3. The ridge is an element that connects all the rafter legs of the system at the top. Installed in a horizontal position.
4. Lathing (Fig. 2) - boards or bars installed to secure the roof. They are located perpendicular to the rafter legs, additionally performing the function of their fastening. They take the main force from the roofing material and distribute it to the rafters. It is advisable to use for the device edged lumber. If you have limited funds, you can use unedged, clearing it of bark. If the roof is made of soft material, the sheathing is made continuous. This option can be made from boards or plywood treated with protective materials against high humidity. When corrugated sheeting is used, the lathing is performed with a certain step, depending on the weight of the material and its design features.
5. Struts are elements made of timber or thick boards that strengthen the main structure. Distribute the force from the rafter legs to the supporting parts. The assembled structure of struts and ties is called a truss - an enlarged part with the necessary margin of safety.
6. Racks - made from pieces of lumber of rectangular or square cross-section. Installed in a vertical position under the ramp. Load from corner connection The roof rafters are distributed through the racks onto the internal load-bearing wall.
7. A tie is a block or board that secures the rafters in a hanging system. Creates a rigid triangle shape between the rafter legs, compensating for the force of spreading.

To make additional parts, you can use lumber with a cross-section similar to the load-bearing parts. In order to save money, you can calculate and purchase products of a smaller cross-section.

Return to contents

Two typical methods of constructing rafter systems

Figure 4. Connection diagram of the lower ends of the parts.

The rafter system of a gable roof can be arranged in two main ways:

• hanging rafter system;
• layered system.

The hanging system is used for buildings with a distance between external walls of less than 10 m, without an internal load-bearing wall in the middle of the building. With another building configuration, a layered rafter structure is used.

If the building has columns located along one of the central axes, it is possible to use combined option. The rafter legs located above the columns are mounted with emphasis on the surface of the columns, and hanging rafters are installed between them.

Return to contents

Hanging rafter system

In structures of this type, the installation of rafter beams is carried out on the surface of the external walls. The disadvantage of this method is that it creates a force that pushes the walls apart. To compensate for the load, the beams are tightened using tightening. The structure takes the form of a rigid triangle that retains its shape under load. In some cases, the role of tie bars can be performed by floor beams. This scheme is used when installing an attic in the attic space.

The designs of hanging rafters can be made in various options:

1. A simple version of an arch with three hinges (Fig. 3) - the structure is a rigid triangle, two sides of which are the rafter legs. The main load creates the bending force of the parts. The force on the third side is aimed at stretching the structure, so instead of wooden part You can use a steel tie. The connection of the lower ends of the parts can be assembled in various ways (Fig. 4), by inserting beams into the tie, using wooden elements or metal brackets.
2. Reinforced structure (Fig. 5) is a gable rafter system used for constructing roofs of large industrial buildings with a distance between walls of more than 6 m. This system is not suitable for use in small residential buildings. A design feature is the distribution of the weight of the tightening on the ridge. Since it is almost impossible to find solid lumber of the required length (6 m or more), the tie is made from lengths. The connection of all elements is carried out by direct or oblique insertion. The central piece is called the headstock. The connection of the headstock with the tightening is done by collet twisting with the ability to adjust the tension.
3. The device of an arch with a tightening in the upper part of the rafter beams (Fig. 6) is used when installing in the attic space of the attic. At the same time, the tensile force in the rafter beams increases. The lower ends of the beams are attached to the mauerlat bars. The fastening should limit the sideways movement of the beams along the beam, but allow sliding across. This ensures uniform load distribution and stability of the entire system. The rafters must form an overhang.

Many options for installing hanging systems have been developed. Most are used for relatively small buildings without supporting structures inside the buildings. For buildings bigger size you need to use a layered rafter system.

Perhaps the main decoration of any house is the roof, without which it is difficult to imagine any structure. The roof gives a private home a holistic appearance and defines his style. However, first of all, it acts as engineering structure, designed to protect people from the destructive effects of the external environment.

Today, the use of various architectural elements in the construction of houses, undeservedly forgotten earlier, is returning to fashion. For example, mezzanines, bay windows, and attics are becoming more and more common, giving the building a stylish and interesting exterior. At the same time, you can achieve a noticeable increase in internal space at a relatively low cost of money.

The roof truss system is considered the most strong, durable structure. It is characterized by ease of installation, ease of adjustment and the ability to withstand heavy loads, with a relatively light weight. The rafter system is a special structure, with a triangle at the base. Its rigidity is achieved by fastening the rafters and the roof frame together. The most common options are made from wooden logs or beams, however, there are also systems made from galvanized steel.

Types of rafter systems

Experts distinguish several types of rafter systems. They are accepted classified by roof shape and type:

• hipped;
• tri-slope;
• gable;
• hip;
• half-hip;
• broken

Gable rafter system roofing is the cheapest and simplest option. The main advantages of this design include simplicity, reliability and the ability to withstand significant loads. At the same time, it is worth describing some disadvantages. Namely, the impossibility of implementing any special design solutions due to the simplicity of the shape of such a roof. However, this minus can easily be compensated by decorating the house with various decorative elements. The second drawback can be called more significant - inner space small in size, significantly different from the parameters sloping roof.

The most common and recognized among lovers of interesting architectural solutions is sloping roof truss system. In this case, there is an opportunity for the manifestation of imagination, of course, subject to established construction standards and strength characteristics. This design can be regular or asymmetrical in shape and is determined based on the structure of the house itself, as well as the design and layout of the interior of the room.

Sometimes you can get an extremely interesting room under the roof by correctly installing the rafter system and organically using a second light or mezzanine. In order to maximize, at relatively low financial costs, usable area home and make it cozy, it is very important to be able to effectively and fully use the available space.

Features and requirements for the rafter system

The size of the rafters, which are elements that determine the strength and slope of the roof, must be calculated individually for each private house, taking into account the total area and geometric shape roofs, as well as the distance between the walls. Depending on the results obtained, it will be possible to determine the appropriate cross-section of the beams. As a rule, this figure is about 1 meter.

In practice they use two types of rafters:

1. An inclined structure, which rests on the walls of the house along the entire perimeter, and in the center it is supported by an additional or intermediate support. It is advisable to use if the distance between several supports is no more than 6.5 m.
2. Hanging rafters, fixed at the top at the ridge and resting on each other. This system is particularly reliable when connecting walls to each other.

In general, the design of the rafter system directly depends on the type of material from which the house is made. For example, for a building built of brick, a rafter system is recommended that rests on a separately constructed support made of small-section beams or a mauerlat. As a support for rafters wooden structure The top crown of the log house is best suited, and for frame-type houses the top frame is used.

Main parts of the roof truss system

The basis of the roof on which it is made installation roofing pie And internal lining premises, is precisely the rafter system. It is often also used as a basis for communications and engineering systems. The set of various components and elements that make up the roof truss system performs the function of transferring power loads directly from the roof to the load-bearing walls of the structure. The main parts include:

• Hanging and inclined rafters.
• Mauerlat.
• Ridge and side girders.
• All kinds of connecting elements, such as struts, diagonal braces, spacers.

As a rule, the load on the roof truss structure is very high. It is determined individually, taking into account design features roofs and local wind and snow loads. The installed rafters must guarantee the retention of such loads, and also have the necessary strength margin to withstand possible gusts of wind or snowfall.

In order to determine the main parameters of the components of the roof truss system, it is necessary perform special calculations. They will help to accurately determine the profile, length and cross-section of each of the structural elements, as well as the features of the interaction of the parts with each other. The strength of the entire structure largely depends on how tightly the units of the roof truss system are connected. Recommended use the following types of connections:

What type of connection is applicable for specific system, can be determined based on the design load, design features and materials used.

Installation principles

Installation work carried out in three main stages. In particular, location-aware markup window openings, hoods, chimneys, mounting the Mauerlat and reliable fastening it to the supporting support. Next, the trusses are erected and, finally, the ridge is installed.

Installation should begin by laying the Mauerlat on top of the walls and attaching the rafters directly to it. They must be installed in the desired position and secured at one end to the support, and at the other to ridge beam. For reliability, the connections can be additionally secured to each other with studs with a diameter of 8 -12 mm.

During construction truss structure most common an error is an incorrect calculation rafter sizes, which can lead to sagging of the roof.

It is necessary to provide for each element and node and understand the technology at the preliminary stage. At the same time, it is also recommended to plan the eaves overhang with a length of 60 cm, which will reduce the effect of weather phenomena on the walls of the house.

For wooden structures, which may dry out over time, most the right option there will be fastenings bolted connections , capable of adding rigidity to the entire structure.

If you follow all the basic rules, installing a roof truss system can be done relatively easily. However, it is important to strictly adhere to the chosen technology to avoid the risk of various problems.

A good foundation does not mean that the house will stand “faithfully” for many years. Another extremely important component is a reliable and high-quality roof rafter system. Let's figure out how it works in the case of a pitched roof, what types there are and what elements it consists of.

Roof rafter systems

What should be the rafters for roofs?

Here are several types of rafters that are most often used in modern construction:

• metal ones are difficult to change, but this material is durable;
• wooden ones are easy to use and change, but require additional processing;
• wooden I-beams (made of timber and OSB) are smooth with a maximum length of up to 12 meters, but the cost is higher than a conventional wooden system;
• reinforced concrete cannot be changed at all, but they are distinguished by their long service life;
• mixed or combined systems.

Each of them has its own pros and cons, which include strength, price, ease of installation, the possibility of small changes associated, for example, with inappropriate dimensions, interaction with environment. This material will discuss the most popular material for making rafters - wood. Let us highlight the main tasks that are set for structures of this type.

First, and most importantly - strength each element. The roof should not deform or move. The basis of the rafter design is a triangle. It is in the form of a triangle that trusses (frames) are made, attached in parallel. Fixed and rigid, they “head” the entire structure.

Low weight. A heavy roof is extremely bad. Therefore, most elements are made from wood. If the weight of the roofing system is large, then it is reinforced metal frame. The base is coniferous wood with low moisture content.

What requirements the tree should respond:

• 1-3 varieties. No chips, knots or cracks.
• Wooden elements should not be less than 5 cm in thickness, and with an area of ​​up to 45 square meters. cm.
• The maximum length of coniferous timber timber should not exceed 5-6 m.
• Mauerlat and purlins are made exclusively from hard wood.

Main structural elements of rafters

Any owner planning the construction of a rafter system must be aware of what it consists of.

1. Mauerlat. The basis of the entire structure. Using this element, the correct load is set on everything load-bearing elements Houses.
2. Rafter leg. The slope of the slope is affected, gives the roof an attractive appearance, and reliably secures the structural parts of the system.
3. Puff. Does not allow the legs to “diverge”. Holds them firmly at the bottom.
4. Run. Attaches the rafter legs at the top of the system (ridge girder) and on the sides (side girder).
5. Lathing. Mounted strictly perpendicular to the beams. Made from cut timber or boards.
6. Posts/Struts. They “add” even more durability to the legs.
7. Overhang. Protects the main structures of the building from various natural precipitations.
8. Horse. The place where the ramps are fixed.
9. fillies. Create an overhang. Necessary when the rafters do not have the required length.

Details of rafter systems using the example of a gable roof, which can be used for various designs roofs

Let's look at such a component of the rafter system as a truss. It is made flat, and, in addition to stretching, it includes braces and the beams themselves. All these parts are fixed in such a way that the load on the main structures is vertical.

In the case where the span is quite large, the truss is made of several components. The bottom of the truss is the attic ceiling. The exact number of farms is determined after serious calculations at each specific site.

Types of rafter systems for different types of roofs

All design options are determined by two main types of rafter systems: hanging and layered.

Hanging

Ideal for gable roof types, with small spans - up to 5 m, without internal partitions. The lower support is the Mauerlat. In such a system, tightening is used, which reduces the thrust of the structure on the main supports of the building.

Hanging roof structure

The hanging rafter beams are located below - they also act as floor beams. In the case where the floors were made of reinforced concrete structures, they can also be tightening the system.

Important additions:

• You should not use legs as the main support element for the roof overhang. More best option- filly (provided that the overhang is no more than 1 m wide). The leg, with this solution, transfers the load along its entire plane to the Mauerlat.
• When the wood has a moisture content of more than 20%, you should prepare in advance for the fact that after drying the system will begin to “walk.” The solution is to use bolts as fasteners, which can always be tightened. But, an even more “advanced” option is “powerful” mounting screws.
• Must be secured to the top of the roof wind board(should go from the Mauerlat itself to the top of the ridge). The corner is organized from the attic. This is needed to create the maximum strong roof, resistant to wind loads.

Layered

They are used for roofs with spans of 9-15 m. At the top, such rafters are attached to a ridge girder, at the bottom - to a mauerlat.

Layered rafter system

If the span is more than 15 m, then instead of a ridge girder, two side girders are installed, which are additionally attached to the posts. In the case where an attic will be created, a wall is used as a support for the layered beams.

Peculiarities:

• Any structural part of such a system should not be thicker than 5 cm.
• The surfaces of the elements must be as smooth and processed as possible.
• You need to be very careful when calculating the loads on each structural element.
• The Mauerlat must be positioned strictly horizontally relative to the vertical supports.
• Symmetry must also be adhered to when installing struts with racks.
• High-quality ventilation is the key to ensuring that your rafter system does not rot in the future.
• At the points where elements connect to stone or brick, good waterproofing is needed.

Depending on the roof shape chosen by the developer, its frame will also be different. We suggest you study various options for the most popular upper structures Houses.

Shed roofs

Manufactured at an angle of 13-25 degrees, such roofs have the simplest (in terms of manufacturing and installation) rafters. In the case of a small building with spans up to 5 m, a layered system is used. In cases where spans are more than 5 m, trusses are additionally used.

Gable

Also a pretty simple option. Especially when an attic or attic floor. Tilt angles - 15-63 degrees. If the main partitions are located at a distance of up to 6 m (relative to each other) - install hanging rafters. For running house sizes of 6x6 or 9x9 meters, we recommend using the following roof design diagrams.

Recommended installation diagram for a hanging truss system for a gable roof

When increasing the size of the house, it is necessary to modify (strengthen) the structure. In such cases, it is necessary to use layered technology.

Options for a gable roof for spans of more than 10 meters: the use of a layered rafter system

Hip or hipped

Rules for the construction of a hip roof rafter system

With tilt angles of 20-60 degrees, and spans of no more than 13 m. Required condition- internal reinforcing elements. For roofs of this type, trusses are used, or rafters are installed for layered roofs.

broken roof

Installation of sloping roof rafters

In its lower part it can have a slope of up to 60 degrees, in its upper part it can be flat. Due to this feature, the attic area becomes somewhat larger. The same types of rafters are used as in the version with hipped roofs. But it is recommended to use trusses.

Additional items

To create the strongest possible roof, each component part of the structure must be very firmly connected to the frame and other elements. In this case, it is extremely important to take into account the strength of the wind and the direction of possible mechanical loads.

Moreover, you should also pay attention to the wood. It may crack due to drying out. Therefore, it is important to create a design in which each element will “work” as harmoniously as possible.

Previously, all structural elements of rafters were secured with notches. But this was not a very “cheap and economical pleasure”, since it was necessary to take wooden elements of a large cross-section.

Methods of attaching rafters to the mauerlat and ridge girder

So, today, not notches are used for fastening, but special bolts and dowels:

Metal linings with anti-corrosion coating are another fastener option. They are mounted on system elements using serrated plates or nails. The advantages of such fastenings are as follows:

1. Low consumption per unit of wood.
2. Easy to install.
3. High fastening speed.

Perforated fastening elements: corners, plates, beam support

Features of installation of the rafter system and mauerlats of gable roofs

Installation diagram of the rafter system in the case of a gable roof

I - mauerlat, II - rafter leg, III - ceiling.

Using narrow rafter legs is a “direct path” to sagging of the system in the future. To prevent this, you need to use a special grid - reinforcement, which includes struts, racks and crossbars. To create it, you need to take wood 2.2 cm thick and 15 cm wide, or use wood plates with a minimum diameter of 13 cm.

Roof rafters - Basic structure stingrays It consists of elements that can be connected to each other by crossbars, spacers, racks, etc. The material for the support beams, in addition to the most common one - wood, can be anything - metal, reinforced concrete or mixed.

Table for calculating the rafter system depending on the distance between each other and the length

The wood (timber) must have a cross-section from 40 by 150 to 100 by 250 mm. This figure depends on the distance of the legs from one another, and the number of sediment loads for a particular area (calculation is carried out separately).

The board should not have more than 5 cm in cross section. Width is directly proportional to length. For example, if your board is 5 m in length, then its width should not be less than 13 cm. The main material of the roof sheathing is also important. When choosing it, you should pay attention to the presence of knots, chips and cracks. If you can’t find the most even pieces of wood, then maximum length knots should not be more than 1/3 of the thickness of the wood.

The last step in installing roof rafters is to securely fasten each element. Staples and metal corners are the most optimal elements for these purposes. But, in modern construction, bolts are increasingly being used.

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

To prevent it from deforming as a result of operation, it is necessary to correctly calculate the cross-sectional size 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 rafter system of a gable roof of a house is, what it consists of, how it is designed and assembled with your own hands.

A rafter system for a gable roof of a house is a system of interconnected supporting elements that together make up 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 rafter frame performs the following functions:

1. Gives the roof slopes the necessary slope. The traditional shape in the form of an equilateral rectangle of a gable roof is given by the rafter frame, which forms the slope between the base of the roof and its ridge. The angled surface allows snow and water to slide freely off the slope.
2. Distributes the load from the weight of the roofing pie. The weight of the roofing pie, taking into account the snow load, can reach up to 500 kg/m2, so the gable roof is subject to intense loads, especially in winter period. The rafters of a gable roof evenly distribute the weight that rests on them, and then transfer the load to the load-bearing walls and foundation of the house.
3. Serves as a basis for attaching 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 should be fixed to the sheathing, which protects against moisture penetration.

Please note that the design of a gable roof truss system is quite complex to design and assemble, especially if the craftsman lacks experience. After all, in order for it to be able to withstand intense loads, you need 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 carried out.

Types of rafter systems

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

An important design characteristic is their load bearing capacity, which determines how much weight they can support without deformation. By characteristic features The following types of rafter systems are distinguished:

Layered

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

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

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

Hanging

The hanging rafter system is distinguished by the fact that its rafters rest only with their lower end on a mauerlat beam installed on the external load-bearing walls. The upper end of the rafter legs of this design does not rest on anything, but seems to hang in the air, which is why 2 types of load arise: bending and expansion.

The thrust load of such a layout of elements on the external 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 structure of a gable roof with hanging rafters consists of triangular trusses, the rigid shape of which is not subject to loads. The complexity of the dangling circuit is believed to be much higher.

The rafter system of a gable roof can be easily installed with your own hands 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 columns, rather than walls, are used indoors as support inside the house. Then hanging and layered rafters can be alternated to strengthen the structure due to 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 using a rigid fastening, but using a movable support. The sliding fastening allows the roof to change dimensions within the range of movement during the shrinkage of the wooden house.

Design

Construction of a rafter system for a gable roof of any of listed types is a set of auxiliary and supporting elements. They distribute the weight of the roofing pie evenly, and also compensate for the bursting and bending loads that arise 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, climatic conditions in the construction region, as well as the slope of the structure. Part rafter frame A gable roof usually includes the following elements:

1. Mauerlat. Install 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 pie. It is made of durable timber with a cross-section of 150x150 mm or 200x200 mm and is attached to the upper chord 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 supports must be placed on it for mounting the ridge girder.
3. Rafter legs. This term refers to frame elements that are made from boards with a cross-section of 150-40 mm and are installed at an angle to the base of the roof, forming an angle of inclination of the slope. The distance between the rafters, their length and thickness are determined using calculations that take into account the total loads to which they are subjected during operation.
4. Puff. A tie is called a beam that is placed horizontally and connects the legs of one rafter pair to reduce the thrust load on the external walls of the structure. The crossbar is a tie installed under the very ridge of the structure.
5. Racks. A stand is a vertical beam placed flat to support the ridge girder. It is easy to determine what distance should be between the racks, because it follows the pitch of the rafters.
6. Struts. Diagonally located supports that support the rafter legs in the middle or at the bottom, preventing them from bending, are called struts.

Please note that determining how to correctly position the elements of the rafter system can only be done by calculating the temporary and permanent loads to which they will be subjected during operation. Calculating the total weight of the roofing pie helps determine the correct distance between the rafters, calculate their length and required thickness.

The calculation of the rafter system of a gable roof 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 calculations are performed in the following sequence:

• Determine the structure and slope of the roof. Exist various ways choice of type and inclination roofing structure. This parameter depends on climatic conditions and performance characteristics selected roofing material.
• Determine the total load on the structure. To do this, sum up permanent loads (the weight of the roofing, the weight of the frame, thermal insulation and ceilings) with temporary loads (snow load, wind load), multiply by correction factor, taking into account the slope of the slopes, and then add 10-15% to this figure so that the frame has some margin of safety.
• Calculate the length of the rafter legs. To do this, they use the Pythagorean theorem, because the 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 cross section of elements. The optimal cross-section of elements is selected from tables in accordance with the length of the rafter legs and the distance between them. The higher these indicators are, the thicker the rafters should be.

Remember that before you calculate the rafters for 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 being covered. The result of the calculation of roof elements should be detailed diagram rafter system, reflecting their sizes and angles between them.

Calculating 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 constructed in areas with a lot of snow cover, and flatter 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 higher the final cost of the roof. Be sure to take into account the requirements of the material:

1. Tiles and slate require a slope of at least 22 degrees, otherwise precipitation will seep through the joints between the elements.
2. Metal tiles are laid at an angle of at least 14 degrees, since they suffer greatly from gusts of wind, they can become deformed or even fly off.
3. The soft roof allows an inclination angle of up to 5-10 degrees, making it possible to cover slopes of any geometry.
4. Ondulin is considered one of the most reliable materials and can be used even for roofs with a slope of less than 6 degrees.
5. Corrugated sheets cannot be laid at an angle of less than 15 degrees, however, it is advisable to treat slopes even with an acceptable slope with sealant for better waterproofing.

Assembly technology

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

Having a frame diagram in front of you, it is much easier to carry out high-quality installation of the rafter system of a gable roof. The technology for assembling the structure implies the following sequence:

1. First, the Mauerlat is laid on the upper belt of the external walls, on which the slopes will rest, and on internal partitions If the system is layered, install a bed. These elements must be firmly fixed using anchor bolts or studs.
2. Then the rafters are fastened. They are fixed with nails to the Mauerlat, and are also connected to each other using a metal plate. It is worth remembering that the rafters are cut to fit the mauerlat timber, and not vice versa. First, the rafters located on the edge are installed in order to set the level along which the remaining pairs will be aligned.
3. After installing the rafters, auxiliary supporting elements, which I will support them - struts, tightening, contractions. To fix the crossbar more reliably, its end is made with a protrusion half the thickness of the beam and it is cut to the rafters, fixing it with nails in several places.
4. A sheathing is nailed over the rafter legs, onto which the roofing material is fixed. The material and pitch of the sheathing are selected in accordance with the characteristics of the roofing material and the slope of the roof.

Remember that a well-designed and high-quality rafter system is the key to the 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

When constructing one-story houses, a roof with two slopes is very popular. This is due to the speed of construction of the structure. In this parameter, only a single-pitched roof can compete with a gable roof. The design of the gable rafter roof is not too complicated. And you will successfully master this work on your own.

Design of a gable roof truss system

A gable roof consists of two inclined surfaces that have rectangular shape. Thanks to this, precipitation, which is represented by rain and melt water, drains from the roof naturally. The gable roof has enough complex design. It consists of the following structural units: mauerlat, rafter system, fillies, ridge, roof overhang, bed, struts, tie-downs, sheathing and racks:

1. Mauerlat. This element performs the functions of transferring and distributing the load created by the rafter system onto the load-bearing walls of the house. To make the Mauerlat, timber is used, which has a square cross-section - from 100 by 100 to 150 by 150 mm. Better to use coniferous wood. The timber is placed around the perimeter of the building and secured to the external walls. For fastening, special rods or anchors are used.
2. Rafter leg. Rafters form the main frame of any roof. In the case of a gable roof, they form a triangle. The rafters are responsible for the uniform transfer of loads to the Mauerlat. First of all, those that arise from precipitation, wind and the weight of the roof itself. For the manufacture of rafters, boards are used that have a cross-section of 100 by 150 or 50 by 150 mm. Choose a rafter pitch of about 60-120 cm, depending on the type of roofing material. When using heavy coverings, place rafter legs more often.
3. Horse. This element connects the two slopes at the top of the roof. The ridge is formed after connecting all the rafter legs.
4. Fillies. They act as a continuation of the rafters and form the overhang of the gable roof. It is customary to install fillies if the rafter legs are very short and do not allow the formation of an overhang. To make this structural unit, take a board that has a smaller cross-section than the rafter. The use of fillies facilitates the construction of the rafter system, as it allows the use of short rafters.
5. Eaves. This part of the design of the gable roof truss system is responsible for draining water from the walls during rain and at the same time preventing them from getting wet and quickly collapsing. The overhang from the wall, as a rule, protrudes 400 mm.
6. Sill. It is located on the inner wall and serves to evenly distribute the load from the roof pillars. To make the bed, a timber is used, which has a cross-section of 150 by 150 or 100 by 100 mm.
7. Racks. These vertical elements are responsible for transferring the load from the ridge to the internal walls. To create this element, prepare a beam that has a square section of 150 by 150 or 100 by 100 mm.
8. Struts. They are needed to transfer loads from the rafters to the load-bearing walls. The struts and ties form a strong structure called a truss. Such a device is designed to withstand loads over large spans.
9. Puff. This structural unit, together with the rafters, forms a triangle. It does not allow the rafters to move in different directions.
10. Lathing. This structure consists of boards and bars. They are attached perpendicular to the rafters. Lathing is necessary to evenly distribute the weight of the roof covering and the loads created by weather conditions onto the rafters. In addition, sheathing is required to fasten the rafters together. When arranging a soft roof, moisture-resistant plywood should be used to create sheathing rather than boards and bars.

Types of gable roof rafter system

There are gable rafter systems with hanging and layered rafters. Ideally, the design contains a combination of them. It is customary to install hanging rafters if the external walls are located at a distance of less than 10 m. Also, between them there should no longer be walls that divide the space of the residential building. The design with hanging rafters creates a bursting force transmitted to the walls. It can be reduced if you make a tie made of wood or metal and place it at the base of the rafters.

The rafters and tightening form a rigid geometric figure- triangle. It is not capable of deforming under loads that appear in any direction. The tightening will be stronger and more powerful if it is positioned higher. The tie beams are the floor beams. Thanks to their use, the hanging rafter system of a gable roof serves as the basis for arranging the attic floor.

In their design, layered rafters have a support beam, which is placed in the middle. It is responsible for transferring the weight of the entire roof to the intermediate columnar support or middle wall located between external walls. It is recommended to install layered rafters if the external walls are located at a distance of more than 10 m. If there are columns instead of internal walls, you can alternate between layered and hanging rafters.

DIY gable rafter system

The roof must be strong to withstand various loads - precipitation, gusts of wind, the weight of a person and the roofing itself, but at the same time light so as not to put much pressure on the walls of the house. A properly constructed gable rafter roof evenly distributes the load across all load-bearing walls.

Calculation of a gable roof

The choice of slope for a gable roof will depend on the material you have chosen for laying on the roof and architectural requirements:

• When erecting a gable roof, remember that it must slope at an angle of more than 5 degrees. It happens that the roof slope reaches 90°.
• For areas with heavy rainfall, and when the roofing does not fit tightly, steep slopes are made. In this situation, the angle should be 35-40° so that precipitation does not linger on the roof. But such an angle does not allow building a living space in the attic. The solution will be a broken roof structure. It will have a flat top part, and at the bottom there is a sharp slope.
• In regions with strong gusts of wind, flat roofs are installed. If constant winds prevail in the area, then make a slope of 15-20° for high-quality protection of the roofing.
• It is best to choose the middle option. Make sure the gable roof is not too steep. But the slope should also not be very gentle.
• When choosing a large roof angle, its windage increases, and, accordingly, the price of the gable roof rafter system and sheathing increases. After all, such a slope entails an increase in the roof area and, accordingly, the amount required material- construction and roofing.

When purchasing materials for constructing a gable roof, it is useful to calculate its area:

1. Find the area of ​​one slope of the structure, and then double the result.
2. Ideally, the slope is an inclined rectangle that is placed along a long load-bearing wall. To determine the area of ​​the slope, multiply its length by its width.
3. The length of the slope is equal to the length of the wall. In addition, the length of the roof overhang above the gable is added to the length. Remember that there are tabs on both sides.
4. The width of the slope is the length of the rafter leg. The length of the roof overhang above the load-bearing wall is added to it.

In order to correctly design the structure, it is recommended to carry out an accurate calculation of the rafter system of a gable roof, including determining the loads and characteristics of the rafters:

1. When erecting a roof for a standard building that has one floor, the design load on the roof will consist of two values. The first of them is the weight of the roof, the second is the load from external factors: precipitation and wind.
2. Calculate the weight of the roof by adding up the weight of each layer of the “pie” - thermal insulation, vapor barrier and waterproofing materials, rafter system, sheathing and the roofing material itself. Calculate the weight per 1 m2.
3. Increase results by 10%. You can also take into account the correction factor. In our case K=1.1.
4. If you plan to change the roof structure over time and increase its angle of inclination, then factor in a safety margin into the calculation. Immediately take higher loads than those you received at the time of calculation. It is recommended to start from a value of 50 kg per 1 m2.
5. When calculating the load exerted by atmospheric phenomena, take into account the climatic features of the area where the building is located. When making this calculation, take into account the slope of the slope. If the gable roof forms an angle of 25 degrees, then accept snow load, equal to 1.
6. If the roof is equipped with a greater slope - up to 60 degrees, the correction factor reaches 1.25. Snow loads for angles greater than 60 degrees are not taken into account.
7. The rafters transfer the entire load from the created structure to the load-bearing walls. Therefore, their parameters must be taken accordingly. Select the cross-section and leg length of the rafters, depending on the current load on the roof and the angle of the slope. Increase the obtained values ​​by 50% to ensure a high safety margin.

Mauerlat installation methods

The construction of any roof begins with the installation of the Mauerlat:

• If logs or beams were used to build the walls, then the top beam will act as a Mauerlat, as shown in the photo of the gable roof rafter system.
• If you used brick to build the walls, then wall up metal rods into the masonry. They must have a thread cut for attaching the Mauerlat. Install rods every 1-1.5 m. Choose rods with a diameter of at least 10 mm. Lay waterproofing between the masonry and the mauerlat.
• For walls made of ceramic or foam concrete blocks, pour concrete on top. Be sure to make the layer reinforced. It should have a height of approximately 200-300 mm. Be sure to attach metal rods that have threads to the reinforcement.
• For the Mauerlat, use a beam that has a cross-section of 15 by 15 cm. It will act as a kind of foundation for the rafter system.
• Place the Mauerlat on the top edge of the wall. Depending on its design, the Mauerlat can be laid along the outer and inner edges. Do not place it close to the very edge, otherwise the wind may blow it off.
• It is recommended to place the Mauerlat on top of the waterproofing layer. To connect all parts into one, use bolts and metal plates.
• To avoid sagging, make a lattice from racks, struts and crossbars. To do this, take boards measuring 25x150 mm. The angle between the strut and the rafter leg should be as straight as possible.
• If you use a rafter leg that is too long, install another support. She should rest on the bed. Each element is associated with two neighboring ones. The result is a stable structure around the entire perimeter of the roof.

Fastening rafter legs

Most the best option gable roof rafter system - a combination of inclined and hanging rafters. This design allows you to create a reliable gable roof and reduce the cost of building materials. Consider the following recommendations when working:

1. Use only the highest quality wood as material. Beams that have cracks and knots should absolutely not be used.
2. The rafters have standard sizes- 50x150x6000 mm. When beams are longer than 6 m, it is recommended to increase the width of the board so that the beams do not break under their own weight. Take boards 180 mm wide.
3. First make a template for the rafter leg. Attach the board to the floor beam and the end of the ridge beam. Having outlined two lines, saw off the board along them. The template is ready.
4. Cut the rafters according to this template. After this, make the top cut on them.
5. Take the resulting workpiece and bring it to the floor beam to mark the bottom cut in place.
6. Install all rafters. At the same time, remember that after installing one leg, you must immediately install the opposite one. This way you will quickly remove the lateral loads on the ridge beam.
7. If the slope is too long, then standard boards will not be enough to make a rafter leg. In this case, you can join two boards together. To do this, sew on them a piece of wood of a similar cross-section. It should have a length of 1.5 - 2 meters. According to the gable roof rafter system diagram, the joint should always be at the bottom. Install an additional stand under it.
8. Attach the rafter leg to the ridge beam using nails. To attach the rafters to the floor beam, use self-tapping screws. Metal mounting plates are also suitable. In addition, a few nails are added.
9. If you are building a structure entirely from hanging rafters, then skip the next stage. When erecting a structure with layered rafters, you need to think about the supports that are installed on the floor. To reduce the deflection of the rafters, correctly calculate the location of such supports.
10. If you are building a gable mansard roof, the intermediate posts will become the frame for the side walls.
11. When performing this work, maintain a certain pitch of the beams. Set its size at the design stage.
12. After installing the rafters, attach the ridge. It is placed along their upper edge. For fastening use metal corners or staples. And the most popular are bolts.

Rigidizing the structure

After installing the gable roof rafter system, strengthen it using the technology presented below:

• For small buildings, such as saunas, cottages, utility buildings, and roofs with a simple hanging rafter system, connect each pair of rafters from below using a tightening, and from above using a crossbar.
• For large buildings that are also lightweight, choose a light roof. The walls must support it.
• If the house is 6-8 m wide, then the structure should be strengthened. Place the support in the middle. Such racks are called headstocks. Place them at each pair of rafter legs.
• If the span of the walls reaches 10 meters, then reinforcing beams will be needed. The struts act as additional support for the rafter legs for tightening. They are attached to each rafter - closer to the ridge or in the middle of the rafter leg. Fasten them to the lower end of the headstock and to each other, as shown in the video about the gable roof rafter system.
• In situations with long roofs, the gable beams should be relieved. This is done by installing braces. The top end should rest against the corner of the gable. The lower one is mounted on the central floor beam. For fastening, use a beam that has a large cross-section. This way you can prevent them from breaking if there are strong gusts of wind.
• In areas where winds prevail, the rafters must be resistant to such influences. Strengthen them by installing diagonal braces. The boards are nailed from the bottom of one rafter to the middle of the next.
• For greater rigidity, when creating the most critical fastenings, it is better not to use nails. Use pads for this and metal methods fasteners Nails cannot provide high-quality fastening, since wood can dry out after some time.

Lathing of the rafter system

The final stage of installing a gable roof rafter system is the creation of sheathing. It is on this that you will lay the roofing covering. Carry out the work in the following sequence:

1. Select dry timber for sheathing. There should be no cracks or knots on it. Nail the beams from below. Attach two boards near the ridge so that there are no gaps. The sheathing must withstand the weight of the upper roofing material and not bend under the weight of the workers.
2. If you are installing a soft roof, make two layers of sheathing. One is sparse, the second is continuous. The same applies to roll roofing. To begin, place boards parallel to the ridge beam that are 25 mm thick and no more than 140 mm wide. A small gap is allowed - no more than 1 cm. Lay a continuous layer on top. To do this, it is better to use roofing plywood, slats or boards of small thickness. After this, check that there are no errors left on the sheathing - irregularities and knots. Also check that there are no nail heads sticking out.
3. Place one layer of timber under the metal tiles. It should have a cross section of 50 by 60 mm. Proceed in the same way when using slate or steel roofing sheets. Maintain a step between the beams, depending on the roofing you choose - from 10 to 50 cm. Hammer the nails closer to the edges of the board, and not in the middle. Drive the hats in deep. This way they won’t be able to damage the roof later. If you are making sheathing for metal tiles, then remember that the connection of the timber at the same level should fall on the rafter.

When you have installed and strengthened the rafter system of the gable roof, you can begin installing the roofing pie. Place between rafters thermal insulation material, a layer of vapor barrier and waterproofing. When using insulation in slabs, calculate in advance the pitch of the rafters for its installation. At the final stage, attach the roofing material.