Scheme of the rafter system of a gable roof. Installation of rafters on a gable roof. Determining the cross-section of rafter pairs

The gable rafter system is chosen by many owners of residential buildings. This is due to its high practicality and ease of creation. If you carefully examine the device rafter system gable roof, then the process of its formation can be done with your own hands. The resulting structure is highly reliable and durable, and also guarantees excellent protection of the structure from cold and precipitation.

Main elements of the system

The design of the gable roof truss system is considered simple. It consists of a variety of elements made from wooden elements, having different lengths, configurations and cross-sections. The main nodes include:

Mauerlat. It is represented by a beam with a square-shaped cross-section. Coniferous wood is usually used to create it. Its dimensions vary from 10 to 15 cm. It is laid along all load-bearing walls of the building. It is fixed to them using anchors or special rods. If you make and attach it correctly, it will evenly distribute the loads from the rafter legs along all the walls of the structure.
Rafter legs. They are created from timber with cross-sectional dimensions of 15x10 or 15x5 cm. When they are properly connected, a roof contour is formed in the shape of a triangle. It must be durable and reliable to withstand heavy loads from rain and wind. The rafter legs should be fastened at a distance of about 1 m from each other.
Sill. It is created from a square wooden beam, the cross-section of which is equal to . It is laid horizontally on a load-bearing wall located inside the building. Due to it, the load coming from the roof racks is evenly distributed.
Puff. This element applies if you select hanging structure. It is installed on top of the resulting triangle of rafter legs, which ensures its stability.
Racks. To create them it is used square beam. They are located in a vertical position. They bear the load from the ridge, after which it is transferred to the load-bearing wall located inside the building.
Struts. The installation of these elements is necessary to obtain a special transmission element located between the rafter legs and various load-bearing parts. Due to their reliable connection with a tightening, the creation of a strong structure is guaranteed.
Lathing. Assembled from bars or boards. Installed perpendicular to the rafter legs. It ensures the transfer of gravity from the roof of the roof to the legs of the rafters. It is advisable to use edged boards. If you plan to create a covering on the roof from soft roofing materials, for example, bitumen shingles, then the sheathing must certainly be continuous.
Horse. It is represented by the topmost element of the entire roof. Due to it, its two slopes are connected. Its assembly is carried out by connecting the legs of the rafters at the top of the roof. It must be located in a horizontal position.
Eaves. It protrudes from each wall of the building by about 40 cm. Its installation is due to the need to protect the walls from water flows resulting from precipitation.
Fillies. Provides the ability to create a roof overhang. They are used exclusively in situations where short rafter legs are used, so they are lengthened by fillets.

Important! The pitch between the legs of the rafters is selected in accordance with the weight of the roof, since the more weighty it is, the smaller this gap should be.

Thus, the design of the rafter system gable roof It is considered quite simple, so making this design with your own hands is not difficult.

Types of structures

The rules and features of the installation of this design depend on the chosen variety.

Types of gable roof rafter system:

All options have their own characteristics, so their characteristics are preliminarily assessed. If you plan to install the rafter system of a gable roof with your own hands, then a simple symmetrical design is chosen.

Important! The basis for obtaining an ideal result is competent calculations, and if they are incorrect, the roof will not be reliable and durable, and it will also be dangerous to live in such a house.

How to choose a material to create a system?

When choosing a material, the following rules are taken into account:

rafters are created exclusively from quality wood, which is free of any rotten areas, damage, knots or other defects;
to form the sheathing, edged boards are purchased;
all wood must be well treated with antiseptics and fire retardants.

Important! The presence of knots is allowed, but their length cannot be more than 1/3 of the thickness of the timber used.

Calculation rules

To make the rafter system of a gable roof reliable and of high quality, a lot of attention is first paid to competent calculations. They should affect all elements of the future design:

Load calculation. Any system is affected by two types of load. Permanent forces will regularly impact the structure, and this includes the weight from the roof covering, sheathing, thermal insulation material, waterproofing, additions and finishing materials used for the attic. Typically this load is 40 kg/m. sq. Variable loads can have different strengths, as they include wind, snow exposure and precipitation intensity. To calculate the load, the wind load of a specific region is multiplied by a special correction factor.
Determination of the angle of inclination. A roof with two slopes may have a different angle of inclination, and it is determined by the roofing material used. If a soft roof is installed, then a slope of 5 to 20 degrees is selected for it, or metal tiles vary from 20 to 45 degrees.
Calculation of snow load. May accumulate on the roof in winter a large number of snow. To avoid any problems with the structure, the frame must withstand these loads. To calculate, you need to multiply the weight of the snow by a correction factor.
Definition . The gap between these elements is usually selected in the range from 60 to 100 cm, and the final choice depends on the roof and the weight of the roof.
Definition . To do this, it is recommended to use the standard Pythagorean theorem.
Determination of the rafter section. This parameter is influenced by several important factors: the load on the roof, the type of materials used, the length of the rafter legs, as well as the pitch between them.

Important! When calculating loads, the possibility of a storm or tornado is additionally taken into account, since if the house is located in a region where such loads can occur, then a safety margin is made for the roof, read more:.

Types of rafters

Before the actual work on creating a gable roof with your own hands, you should make a special plan, which will contain a drawing and layout of the entire structure. In this case, it is taken into account which rafters will be used, since the following types can be used:

. Suitable for small buildings. Their installation involves fixing the legs to the load-bearing wall of the structure, as well as to the ridge girder. A peculiarity of the use of these elements is that the rafter legs are subject to a bursting force, and to reduce this influence, puffs are used. They can be made of wood or metal.
Layered. Suitable for roofs of any shape and size. The layered structure is used in conjunction with racks and beds. The bench is laid parallel to the fixed Mauerlat, so a certain part of the load is transferred to it. This allows you to tilt the legs of the rafters towards each other, which are additionally supported by the stand.
Combined. They are used when using unusual configurations of gable roofs.

After determining the basic design parameters, the calculation of the required amount of material begins. Next, you can begin to directly create the rafter system.

Installation of the structure

A do-it-yourself rafter system for a gable roof is created only after preliminary drawings and plans have been generated. The scheme of future contraction must be clear and correctly calculated. To do this, it is recommended to use special computer programs.

Important! In the presence of Money it is allowed to contact specialized construction companies for correct calculation.

Installation of a gable roof truss system is divided into successive stages:

To the walls of the building. Its installation is carried out along their entire length. If the house is made of logs, then the mauerlat acts as its upper crown. If cellular concrete or brick is chosen for the building, then it is mounted on top of the load-bearing wall along its entire length. It is necessary to splice the mauerlat, for which the beams are sawn at right angles and connected with bolts. It can be mounted offset to the side of the wall or in its center. Laying is done on a layer of waterproofing, for which roofing felt is usually used.
Creation of roof trusses. To do this, it is allowed to install beams on the roof or form a structure on the ground, after which it is raised to the roof. The second option is often chosen, since it is difficult to carry out work on the roof of a house. But to lift the constructed structure you will have to use special equipment. Before connecting the legs of the rafters, their correct size and location are checked.
. The formed pairs are lifted to the roof, after which they are laid on the Mauerlat. To do the job correctly, special cuts are made at the bottom of the legs. The process begins with the ends of the roof, located opposite to each other. To obtain an ideal result, temporary fasteners are used when installing elements. A rope is stretched between the fixed pairs, making installation of subsequent elements simplified. All rafter legs are mounted, and the correct pitch between them is checked. Next, a special ridge support is installed. All additional elements, used in the rafter system, are fixed by cutting and staples. It is allowed to lengthen the rafter legs if necessary.
Installation of the ridge. It is created using a competent connection on top of all rafter legs. To form it, different methods are used, and it is possible to use a support beam for this or you can work without it. If timber is used, it is permissible to place a ridge on it or use the cutting method.
The rafter system is considered completed, but in order for it to be strong and reliable, all elements must be thoroughly secured, so all temporary fasteners are eliminated, in place of which high-quality products are used to fix all parts of the system.
Installation of sheathing. This design is designed for easy movement on the roof, and also serves as a basis for laying the roof. Its type and parameters depend on the chosen roof. A continuous sheathing is created if a soft roof is chosen. has a distance between boards within 35 cm. For slate, this parameter is 44 cm.

21.02.2017 1 Comment

The rafter system of a gable roof is a simple design that can be installed with your own hands even by a novice developer. You just need to make preliminary calculations, familiarize yourself with the details and stages of roof construction, and calculate the materials needed for installation. When making calculations, it should be taken into account that the load-bearing capacity of a gable roof depends on the influence of loads from wind, snow, and the weight of materials on it.

To make the process of building a gable roof truss system as easy as possible for you, detailed information is presented below. step-by-step instruction for installing a rafter system with your own hands.

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Requirements for building materials

For the installation of a rafter system, the best option would be to use lumber from coniferous species wood - pine, spruce or larch, grades I - III.

The material for the rafters is taken at least grade II, the mauerlat is made from boards or timber of grade II, material of grade II is taken for racks and purlins, the sheathing is made from lumber of grades II-III, it depends on the roof. Crossbars and tie-downs are made of Grade I material. Grade III material can be used on linings and linings.

Note! The lumber must be dry with a moisture content of no more than 20%. Before installation, it should be treated with fire retardants and antiseptics against fungal diseases.

Lumber should be stored under a canopy, providing protection from the sun and moisture. Level the storage area and cover the lumber with pads for ventilation.

For installation you will need fastening elements: ties, plates, studs, bolts with washers and nuts, self-tapping screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when attaching the Mauerlat; they are secured with nails or self-tapping screws.

KR corners serve to attach the rafters to the mauerlat and prevent the rafters from moving.

All fastening material must be made of high quality material and have corrosion protection.

Tools for constructing a rafter system

To install a gable roof rafter system, you will need the following set of tools:

tape measures of different lengths 5, 10, 20 meters;
markers, pencils;
cord for tensioning;
hammers, for various purposes, nail puller;
scissors, for cutting;
roofing knife;
putty knife;
scotch;
hacksaws, electric saw, electric drill with various drills and attachments;
screwdriver with attachments;
markings, horizontal and vertical levels;
slats, rulers;
polyurethane foam;
safety belt and rope - for safe work.

Keep all tools on the roof in a tool bag for safety reasons.

Types of rafter systems for a gable roof

Sent rafters

They rest on the mauerlat and racks installed on the internal wall, with a pitch equal to the rafters. To provide rigidity for spans of 6 m, additional struts are installed.

Scheme of layered rafters of a gable roof

Hanging rafters

If the building is small in width, you can arrange a rafter system where the rafters rest on the mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Such roofs can sometimes be installed without a Mauerlat. The rafters are installed on the wall using spacers; in this embodiment, a bending moment acts on the rafters.

To unload, wooden or metal plates are installed. They securely strengthen the corner. For hanging rafters For a larger span, a headstock and struts are installed. For hanging systems, the rafters are made with a larger cross-section, and lumber is chosen at least grade I II.

Scheme of hanging rafters of a gable roof

Calculation of the rafter system

You can determine the cross-section of a gable roof beam required in a rafter system by collecting all the loads acting on it: the weight of the covering, sheathing, snow, wind pressure, precipitation.

Constant loads can be determined by the weight of 1 m 2 of roofing and sheathing. It is important that the weight per 1 m 2 of roofing be in the range of 40-45 kg.

Variable loads from snow and wind are calculated using tabular values of SNiP normative documents, depending on the height of the building and temperature zone. The load from snow is equal to its weight multiplied by a coefficient depending on the slope of the slope. All these calculations are performed during the project.

What if there is no project and the roof is being erected on a small building? You need to look at the construction of a house in the neighborhood, which is being carried out according to a design whose roof area is the same as your building. The gable roof rafter system will serve as a model.

Dimensions of timber for rafters

At the top point a ridge is laid that connects the rafters. The height of the ridge depends on the slope of the roof. The slope is affected by the choice of coating material. The minimum sizes are:

for tiled roofs, slate 22 gr.;
for metal tiles - 14 g;
ondulin - 6 g;
corrugated sheeting - 12 gr.

The optimal angle is 35-45 degrees. tilt, ensures rapid discharge of water and snow. In regions with strong winds, the roofs are made flat and then the angle of inclination is within 20-45 degrees.

The height can be determined using the formula: H=1/2Lpr*tgA. Where A is the angle of inclination, L is the width of the building.

The task is simplified when using a ready-made table. The coefficient depends on the width of the building and the angle of inclination. Multiply the coefficient by 1⁄2 the width of the building.

The rafters are made from pine or spruce bars, with a section of 50x100 mm, 50x150 mm.

The size of the rafters depends on the pitch. The pitch of the rafters is smaller, a larger number is installed, and the cross-section will decrease. The distance between the rafters on a gable roof ranges from 600 mm to 1800 mm, it all depends on the design of the roof and the materials used for its construction.

Table of rafter sizes, depending on the step of their installation

Length rafters, mm	Distance between rafters, mm	Rafter beam cross-section size, mm
up to 3000	1200	80×100
up to 3000	1800	90×100
up to 4000	1000	80×160
up to 4000	1400	80×180
up to 4000	1800	90×180
up to 6000	1000	80×200
up to 6000	1400	100×200

The roof does not end at the level of the walls; it is extended outward by 500 mm. The rafter leg can protrude, or a board or block can be built up. In this case, moisture does not get on the wall and the foundation is not poured.

Step-by-step installation of a gable roof truss system

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

Mauerlat.
Lay down.
Racks.
Rafters.
Struts.
Puffs.
Lathing.

Mauerlat installation

Fastening the Mauerlat to a monolithic reinforced concrete belt

Mauerlat evenly distributes the load on the walls of the building; its installation can be done in several ways:

attached to the wall through a reinforced concrete belt with studs;
studs are inserted into the masonry;
simple and common way to simple roofs, fastening with wire rod.

For it, take timber with a cross section of 100×100 mm, 150×150 mm or 200×200 mm. Which section to choose depends on the size of the roof and its covering. The Mauerlat is joined along its length; to do this, make 100 mm cuts, 500 mm long, fold the bars and fasten them with pins.

In the corners, the mauerlat is tied with notches into the floor of the timber, fastened with staples or bolts. U wooden buildings, Mauerlat is the last crown. On brick walls, make a monolithic reinforced concrete belt with a cross-section of 400×300 mm. Along the belt, place threaded pins 12 mm in diameter, every 120 mm, for fastening.

Drill holes with a diameter of 12 mm in the Mauerlat, lay them so that the pins go into the holes. Tighten the top with nuts. First, we lay two layers of roofing felt or roofing felt under the block. WITH outside brick the walls and mauerlat. Lay the Mauerlat on a horizontally and vertically level base. You need to check with a level that the surface is horizontal. Check diagonals. If necessary, level with pads.

Installation instructions for beds, racks, rafters, struts and tie rods

The installation of a gable roof rafter system with your own hands is carried out in the following order:

Install the beam with the rafters in place.
Mark the installation step of the rafter legs.
Prepare according to the size of the rack.
Install them if there is a need to secure them with spacers.
Lay the purlin. Check geometry. Install fasteners.
Try on the first rafter leg and mark the cutting areas.
Mark the points and install the rafters at the beginning and end of the roof, stretch the cord between them in order to align the remaining elements along it.
Having installed the rafter leg, we first attach it to the mauerlat, then to the ridge purlin, to each other.
Screw each second leg to the mauerlat with wire.

The rafters are fastened to the mauerlat using notches, stop corners and a hemmed support bar. Secure with nails or staples.

Methods for attaching rafters to the Mauerlat

Install the support posts on the beds or pads and overlays. A log is a beam 50×100 mm or 50×150 mm, laid on the middle wall along a layer of roofing felt. Place under the linings brick pillars, 2 bricks high.

The rafter legs are connected to each other at the ridge. Let's consider the common connection nodes of the rafter system:

They make cuts at one leg and cut down at the other. Insert one leg into the cut of the other and fasten with a bolt.
Install overlays, wooden or metal.
Using notches in the purlin, they are secured with nails or bolts.

Methods for connecting rafters on a ridge

To ensure the roof's resistance to wind loads, tie-rods, struts and purlins are installed. The tightening is a 100×150 mm block, purlins and struts are made from a 50×150 mm or 100×150 mm block.

With the installation of contractions, the reliability of the rafter structure increases. The sections of the timber are the same as the rafters. They are attached to the legs with bolts or nails. The device of struts adds rigidity to the structure. They are installed tightly to the surface of the rafters

The lumber has a standard length of 6 m. The rafters can be longer. Then you need to dock them. There are several connection methods:

Fasten by placing bars on both sides at the junction, connecting them with nails in a checkerboard pattern.
Connect with an overlap, one part of the rafters to another, at a distance of 1 meter, fasten with nails in an alternating order.
Make a cut obliquely, cut out part of the rafter legs, connect them, strengthening them with bolts.

Sheathing device

Lathing is installed along the roof rafters. It serves to distribute the load from roofing material and snow onto the rafters. Plays the role of an air gap between the roof and the rafter system.

The design of the sheathing depends on the roofing material used:

under soft tiles make the sheathing continuous, lay an anti-condensation film on the rafters, press it on top with a counter batten, nail the sheathing onto it, then OSB boards and underlayment carpet, lay tiles on top.
Under the roof made of corrugated sheets, the sheathing should be sparse. The pitch of the sheathing depends on the brand of corrugated sheeting, its thickness and the angle of inclination of the roof.
The lathing for standard slate should be made in increments of 500 mm from a bar of 75×75 mm or 50×50, as well as boards from 30×100 mm. It is necessary to take into account the design features of the roof, when final choice suitable option.

The lumber from which the sheathing is made is first or second grade pine. It is advisable to take the width no more than 14 cm. With a wider width, the boards may warp and damage the roofing. The length of the nails should be three times the thickness of the sheathing. Lay the boards along the ridge. Install the first board of greater thickness to the height of the roofing.

Install continuous sheathing along the roof slope.

The first layer is to place a board along the ridge from it at a distance of 500-1000 mm to the next one and so on. Lay the second layer of sheathing along the rafters. Place the joint between the boards only on the rafters at intervals. Sink the nail, head and all, into the flesh of the wood.

Cornice overhangs

They are installed to protect against precipitation and play an aesthetic role. Eaves overhangs are arranged tightly without gaps. The final stage of installing the roof.

Diagram of the eaves overhang of a gable roof

Gable

The gable roof has two gables. They have the shape of a triangle, with the apex at the ridge and the sides coincide with the slopes of the roof. The gables support the rafters and enclose the attic space. They protect from wind and precipitation and provide stability to the roof.

In wooden buildings, the pediment is framed. In brick buildings, frame or brick. Gables made of brick or gas block are erected before the roofing is installed. They require very precise execution.

Frame pediments fit into the finished opening when the rafter system is already assembled.

The frame is made of bars or boards. The frame elements are connected on tenons or in the wood floor, all fastened with nails. They are sheathed by nailing boards, lining or siding, maintaining the color scheme in the decoration of the building facade. To construct a window opening, an additional frame is made under it according to the size of the window. If the attic is insulated, then the gable also needs to be insulated. The insulation is placed in the middle of the frame. Mineral wool insulation with reduced flammability is used. On the outside, the frame is covered with a hydro-windproof film or windproof membrane, with inside a vapor-proof film or a vapor-proof membrane is nailed under the finishing material.

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Thanks to its simple design, ease of maintenance and durability, ensuring long-term operation, a gable roof is the most common solution when arranging houses.

Types and features of a gable roof

The shape of the gable roof is determined at the design stage. It largely depends on the further use of the attic space. There are three main types of gable roof:

Symmetrical. The most common option provides reliable device and uniform load distribution. There is virtually no risk of rafters bending down. A significant drawback is the impossibility of arranging an attic. Sharp corners form areas of the attic that are unusable.
Simple asymmetrical. The formation of one angle exceeding 45° ensures an increase in usable area. This allows you to organize additional living rooms. Uneven distribution of load on the foundation and load-bearing walls causes difficulties at the stage of calculations for installing rafters.
Broken. The fracture of a gable roof can be internal or external. Thanks to non-standard design it becomes possible to use the attic space to arrange a full second floor. Calculations for installing rafters become much more complicated.

Calculating the correct angle of inclination is a key task prior to installing rafters for a gable roof. The climatic features of the region are taken into account. The presence of frequent and heavy rainfall necessitates the need for a steep slope of the gable roof. Installation of flat slopes is preferable in case of significant wind loads. With a possible range from 5 to 90 o, the most common roof option is one with a slope of 35 to 45 o, characterized by savings in material consumption and uniform load distribution.

Rafter system options

Mauerlat and rafter system - load-bearing elements gable design. The rafters themselves consist of several parts:

rafter legs and tie rods connecting them and imparting rigidity;
vertical racks;
crossbars;
ridge and side girders;
longitudinal struts, in regions with significant snow and wind loads is performed additional installation diagonal struts;
spacers;
bed and sheathing.

Advice ! The rafter layout necessarily includes the installation of a chimney and a ventilation shaft.

For the selected gable structure, there are three options for installing rafters. Let's look at the features of each method.

If the roof width is less than 6 pm, the option of installing hanging rafters is considered. The process involves fixing the leg between the ridge girder and the supporting wall. This ensures a reduction in the impact of bursting force on the rafter legs. The connection of rafter elements is carried out using tightening made of wood or metal. Their installation below allows them to serve as load-bearing beams. An indispensable condition is a reliable fixation of the tightening, since it is subject to bursting forces.
Layered rafters are not limited to the size of gable structures; they include beams and posts. A significant advantage of this type of rafters is ease of installation. The practicality of the design is overshadowed by the presence of a stand.
Complex configurations of gable roofs require the installation of combined rafters.

Having determined suitable look rafter system, proceed to calculating the amount of material. In this case, each element of the roof needs a separate drawing and recording of the obtained calculation results.

Calculation of the rafter system

In fact, the rafter system is triangular elements connected together, characterized by maximum rigidity. If the gable roof has a broken structure, the irregular rectangles need to be divided into separate components, followed by calculation of the loads for each part. On final stage the data is summarized.

Determination of permanent and temporary loads

An integral condition for installing rafters is determining the loads on a gable roof. They are divided into constant, variable and special. Components of quantities permanent loads- weight of the sheathing, finishing materials attic, insulation and other elements that generally form the weight of the roof. On average, this load on the rafters is 40-45 kg m2.

Advice ! Calculation of the strength of a gable structure provides for a 10% margin.

Based on the indicators in the table indicating the weight of individual roofing materials, you should adhere to a maximum load of 50 kg per 1 m 2 of roof area.

The very name of variable loads indicates their inconsistent action. This includes wind force, snow cover and other types of intense influence of weather conditions. A gable roof is like a sail; an incorrectly calculated angle of inclination can provoke its destruction under the influence of strong wind. To calculate this parameter, we turn to the indicators specified in SNiP “Loads and impacts”, taking into account related factors (location of the house on open space or among high-rise buildings). Determining the influence of snow cover on a gable roof is the product of the weight of the snow and a correction factor that takes into account aerodynamic effects. According to SNiP, the weight of snow ranges from 80-560 kg/m2. The dependence of the coefficients on the angle of inclination of the roof is presented in the following figure:

If the angle exceeds 60°, this parameter is not taken into account due to the impossibility of retaining snow cover on a gable structure. Special loads are provided in regions with increased seismic activity, with possible storm winds or tornadoes, which is not typical for most territories.

Calculation of technical parameters of rafters

The installation of the rafters is based on the shape of the gable roof; the more complex it is, the more rafter elements the system includes. Using soft roof, the angle of inclination of the roof does not exceed 20 o; steeper designs require the installation of ondulin, metal tiles or standard slate.

The choice of rafter pitch depends on the roofing material used and the weight of the gable structure; it varies between 0.6-1.0 m. The number of legs is determined by dividing the length of the roof by the gap between the rafter pairs and then adding 1. The result shows the number of legs per one side of the roof, to determine overall indicator the figure is doubled.

Installation of rafters will not be complete without determining their length, for which the Pythagorean theorem is used (c 2 = a 2 + b 2), where:

The roof height (a) is selected based on the possibility of further use of the attic space.
Let us denote half the width of the house as b.
The hypotenuse (c) represents the desired quantity - the length of the rafters.

Note! The result obtained should be increased by 0.6-0.7 m for cutting and moving the rafter element beyond the wall.

If the maximum beam length of 6 pm is not enough to install the rafter leg, it can be spliced by joining or extending.

When determining the cross-section of the rafters, the following factors are taken into account:

constant and variable loads:
what roofing material will be installed;
type of wood used;
the length of the rafter legs and the pitch between them.

The table below will help you determine the parameter you are looking for:

Rafter installation pitch (m)	Rafter leg length, m
Rafter installation pitch (m)

Analyzing the data, a pattern emerges: increasing the installation pitch of the rafters proportionally increases the load on each leg, therefore, its cross-section should increase.

Approximate cross-sections of individual elements of the rafter system of a gable roof are given below:

Installation of a gable roof

After carefully checking the calculations, they begin to install the Mauerlat.

Mauerlat

Installation of the Mauerlat includes the following steps:

Fixing the beam on the wall intended to support the rafters. If the house is made of logs, the function of the Mauerlat is performed by the upper crown. Buildings made of porous material require the installation of a Mauerlat along the entire length of the load-bearing wall.
Overshoot problem standard sizes lumber when installing the mauerlat is solved by splicing them.
To connect the Mauerlat of a gable roof, the timber is cut exclusively at a right angle; the function of the connecting link is performed by bolts. The use of wire, nails and wooden dowels is not acceptable.

Installation of the Mauerlat can be done in the center of the supporting wall or offset. When fixing the structure, at least 5 cm must remain to the outer boundary of the wall. The use of waterproofing protection will protect the wooden frame of the gable roof from damage by moisture. Reliable fastening is an essential condition for installing rafters and mauerlat on a gable roof. There are several ways to fulfill this requirement:

Anchor bolts are ideal for a monolithic structure;
It is preferable to equip log houses with wooden dowels;
porous materials combine well with reinforcement or studs;
annealed wire is used as an additional fastening when installing rafters;
hinged fastening involves displacement of the rafter legs during the process of shrinkage of the house.

Installation of rafters

Installation of rafter pairs is carried out in two ways: directly on the roof, which is very impractical, or on the ground. With the second method, difficulties may arise when moving collected elements on the roof. The installation of the assembled pairs on the mauerlat is preceded by the preparation of cuts; they are made exclusively on the rafter leg, so as not to weaken the base of the wooden structure. Mounting options are shown below:

To install paired rafters, temporary spacers and struts are used. Ridge knot formed by the connection at the top of the rafter legs. The process involves several options for completing the task:

the small design of the gable roof allows for the absence of a support beam;
large dimensions require the use of rafter beams, which subsequently serve as support for the rack.
cutting method.

Arrangement options are shown in the photo:

Installing the sheathing makes it easier to attach the roofing material; its pitch directly depends on the coating used:

a maximum pitch of 44 cm is possible when arranging the roof with slate or corrugated sheeting;
a distance of 350 mm will be sufficient when covering with metal tiles;
soft roofing requires continuous sheathing.

Installing rafters contains a lot of nuances that are difficult to foresee in advance. Templates made from thin boards can make it easier to prepare cuts and cuts. The video will also answer some of your questions.

A roof with two slopes is the most common option for completing the box of a private house. When manufacturing it, it is important to correctly select the sections of the load-bearing elements, securely fasten the nodes and choose the right type of structure. The rafter system of a gable roof is not very complicated and can easily be made with your own hands.

Classification of rafter systems according to the method of support

The design can be classified according to two criteria. The first of them is the method of supporting load-bearing elements. The gable roof truss system of the house in this case includes the following types:

with layered rafters;
with hanging rafters.

The construction of a roof using layered rafters involves supporting them at two points. The design in this case avoids the occurrence of serious expansion. To do the installation yourself, you will need the following basic elements:

rafter legs;
Mauerlat;
crossbar;
intermediate posts and struts for large spans of load-bearing beams;
sheathing and counter-lattice;
lining thrust bars.

At the top point, installation involves resting on the crossbar. The installation also provides support at the lowest point - the Mauerlat. You can assemble such a structure for your home with your own hands only in two cases:

A layered system is possible if the distance between the gables is not large. That is, such an installation is suitable for small house with your own hands. The longest length of the building, which allows the installation of a wooden crossbar without additional reinforcements, is 6 m. For large spans, it will be necessary to install metal beams. When using wooden beams, it will be necessary to provide intermediate posts, which are placed on average every 2 meters. This can only be avoided by using laminated veneer lumber of a sufficiently large cross-section as a crossbar. In this case, a free layout of the space becomes impossible - the racks in the middle of the room cannot be removed.
The second option, when installation of a layered system is possible gable roof with your own hands is the presence of a wall in the middle of the house. The device in this case provides that the beam on which the rafters will rest at the top point will transfer the load to interior wall. In this case Basic structure should not be confused with the septum. The partition rests on the floors, and installing the wall of the house with your own hands involves resting it directly on the foundations. This device is suitable for buildings with sufficient width, where it makes sense to install a wall fence in the middle.

The second option is hanging rafters. They are more complex to calculate, but allow installation in the under-roof space of a free-plan house. The design assumes the absence of a supporting wooden or metal beam in the upper part. Installation involves supporting the rafters only at the lowest point. At the top, the supporting beams are securely connected to each other. Installing such a system resembles a farm. The structure works under tension, so it is important to prevent excessive horizontal load on the walls of the house. This can be accomplished by performing the following activities:

device monolithic belt along the edges of the walls;
it is necessary to securely fasten the gable roof mauerlat to the wall of the house with your own hands;
To eliminate the thrust, a contraction is established.

The screed or screed becomes one of the significant elements of the gable roof of a house. It prevents the walls from expanding under the influence of thrust. The following types of fights can be distinguished:

located in the attic floor level;
located at the attic ceiling level.

It is worth noting that the second option provides less reliability, since the higher the element is mounted, the stronger the impact the rafters have on it. If the contraction turns out to be too long, you need to strengthen it with your own hands. To do this, additional elements of the gable roof of the house are installed - pendants. They connect the ridge to the middle of the puff, which prevents it from sagging.

The rafter system of a gable roof with hanging rafters allows installation with pre-assembly of trusses on the ground, after which they are lifted onto the roof and secured.

This option is suitable only if you have lifting equipment, since the finished gable roofs of the house will become too large and heavy to lift with your own hands.

Classification by type of stingray

The second division can be made depending on how the ramp line is designed. The views here suggest two options:

With straight slopes. The easiest way to do it. Allows you to get the job done without major difficulties. The disadvantage of this do-it-yourself roofing option is the reduction in attic space.
With broken slopes. These types of roofing are more difficult to implement. It is assumed that there is a line along which the angle of inclination changes. The angle of inclination of the lower part of the slope must be made larger than that of the upper one. This way it turns out to raise the attic ceiling and increase free space. The roof is installed with the installation of an additional crossbar at the fracture site.

These types require a choice between them depending on the wishes of the future owner of the building.

Basic roof elements

The rafter system of the gable final part of the building consists of many elements. Installation should begin with a detailed study of each of them and the selection of their sections.

Mauerlat

When installing elements under metal tiles or other coverings, it means using timber with a cross-section of 150x150 or 200x200 mm. It is this size that allows for the most optimal distribution of the load. Next, you will need to choose a fastening method; it depends on the material of the walls. There are several options:

Frame, timber or log walls do not require installation of a Mauerlat. In the case of a frame building, the support for the rafter legs is the upper frame of the walls. When building fences from timber or logs, the upper crown becomes the Mauerlat. It is important to properly secure these elements in the wall structure.
When using lightweight concrete for construction, additional reinforcement will be required. TO lightweight concrete include materials such as foam concrete, slag concrete, expanded clay concrete. They can collapse if the roof is not placed centrally on them. To distribute the load evenly, a monolithic reinforced concrete belt is poured along the edge of the walls. During work, special wire, pins or bolts are placed in it, onto which the Mauerlat will be attached.
For brick structures, a reinforced concrete belt may not be required.. In this case, to connect to the strapping beam, a wire is inserted into the masonry, which is then wrapped around the mauerlat and twisted. The second option - one row before the walls are cut, they insert into the masonry from the outside wooden blocks, impregnated with antiseptic. Such plugs and Mauerlat are fastened with staples. It is also possible to use studs and bolts, the fastening of which will require pouring a monolithic belt.

An important point is waterproofing.

When installing, it is important to provide roofing felt, linochrome or waterproofing at the junction of concrete or brick with wood. This is required to prevent wood from rotting upon contact with material of a different moisture content.

Rafters

After securing the Mauerlat, the rafter legs are installed. Their cross-section is selected depending on the pitch of the load-bearing beams, their span, snow load and type of coating. When installing a frame under metal tiles at a pitch of 60 cm, it is recommended to follow the following recommendations depending on the span:

3 m – 4x15 cm;
4 m – 5=15 cm;
5 m – 5x17.5 cm;
6 m – 5x20 cm.

Table of average values of rafter legs

These are average values; to perform a more accurate calculation, it is better to contact a specialist or study additional literature.

There are two ways to attach the rafter legs to the mauerlat:

with a notch;
without her.

Attaching rafter legs to the mauerlat with and without a notch

In the first case, wash down strapping beam, in the second, a special board is nailed to the rafters, which becomes a thrust block. Further, for both methods, the work is performed in the same way. Using metal corners, the inclined beam is fixed so that it does not move relative to the design position along the mauerlat. Additionally, nails are driven in at an angle.

Scheme of fastening rafters using wire and staples

In addition, you will need to fasten the rafter to the wall. This activity is provided for in regulatory documents. You can do this in two ways:

on brackets (suitable for wooden buildings);
using twisted wire (a more labor-intensive option, but the only one possible for stone houses).

You can perform fastening according to the norms through one leg. This is necessary to more securely attach the roof to the frame of the house.

If the work is done correctly, you won’t have to worry about its condition even in the strongest winds.

Racks, ties, struts

Such elements are most often made from boards. Optimal thickness is in the range of 32-50 mm. The exception is racks. Here you can use boards with a thickness of 50-100mm. Fastening is carried out on studs or using support bars.

Are you already at the finish line in building your dream home, and it’s time to understand the intricacies of the rafter system? Let's just say: pleasant worries await you: calculating the angle, weight and safety factor of the rafters, an agreement with a familiar craftsman or company, or preparing everything necessary tools for independent carpentry work.

And so that tomorrow all these worries do not become a headache and you do not worry about whether this or that knot is being done correctly, we have prepared this article for you. So, let's figure out how to make high-quality rafters for a gable roof with your own hands so that it is no worse than purchased ones.

Short production times.
Technological precision of all details.
Identical, already adjusted dimensions of all structural elements.

But then be prepared for the following disadvantages:

High cost (at least twice as much as if you planed the rafters yourself).
Delay in delivery (especially during the season).
Using low-quality or under-dried wood (and then the roof will “sink”).

So convenience or quality? If this is not your first time carving or planing something out of wood, feel free to take on making rafters! Here's what it all looks like in real life:

Rafters in the construction world on in simple language It is customary to divide the main ones, i.e. load-bearing ones, on which the roof is supported, and auxiliary ones, which are located inside the roof and serve as support for hemming the ceiling and walls of the attic (if one is planned). The strength and reliability of the future roof depends on how accurately and correctly you calculate the rafter system in advance.

The rafter system of any gable roof itself consists of the following basic elements that you need to make:

Mauerlat.
Vertical racks.
Crossbars.
Rafter legs.
Spacers.
Ridge run.

Complex roofing structures with multiple elements it is better to entrust the calculation to a professional, but with a small roof of a private house you can handle it. For this you will need these simple formulas, which will help you find out how thick the rafters should be, with what slope and what span:

How to draw up a project for a future roof?

Used in roof construction Golden Rule- measure seven times, and cut only once. And first of all, it is important for you to understand that each rafter leg has its own individual location. Therefore, first be sure to draw up a detailed project, and it is better to special program. Only after this, using your 3D model of the future roof, mark exactly where and what kind of connections the rafters will have with the Mauerlat and with each other.

It is important to determine as accurately as possible the angle of inclination of the rafters and at what angle they need to be cut. And don’t worry about how to make all these rafters for a gable roof yourself: all you need is a regular machine.

Determining the angle of inclination of the roof: calculating the loads

The angle of inclination of a gable roof is made from 5° to 90°. But the most proven and standard option is 35°-40°, where loads are distributed most rationally and building materials are consumed.

Straight slopes are built when in the future there will be only a non-residential attic under the roof, main function which is ventilation and heat exchange regulation. But when the under-roof space is planned to be residential, attic, they initially plan a so-called sloping gable roof. Its difference is that the slopes in the middle have a kind of kink, which changes their angle to a steeper one. This design is quite suitable both for arranging an attic and for protecting the entire house from bad weather.

Please note that most roofing materials are only suitable for pitches greater than 45°.

Constant and variable roof loads

The same loads determine what rafter pitch you need for your gable roof. This table will help you choose the right section of rafter legs:

Indicators of rafters for deflection

Even strong-looking rafters may not be suitable for constructing the roof of a residential building due to the fact that they have insufficient deflection properties. Exist individual items in the section of SNiPs, which are called “Loads and impacts”.

And the easiest way to increase the deflection strength of rafters is to make the cross-section larger. It’s a little more difficult to strengthen it with a special beam, bringing its edge to the strut.

Reinforcing elements for rafters

The more racks, struts and contractions, the more durability and stability the entire rafter system has.

If you have any suspicions or even an exact estimate that simple design roof will not withstand future loads, make additional reinforcements for it. Such prevention will never hurt, but it will save you from many problems. Note that it is especially offensive when the garage roof falls in - right on top of the car. And such problems are not a joy for a residential building.

The rigidity of the rafter structure is enhanced by struts, additional purlins and support posts. The braces are designed to reduce the span of the rafter legs. Their angle of inclination to the horizontal is usually at least 45°.

A purlin is a horizontal beam, which is located parallel to the ridge and is fixed to vertical racks. More details in the video:

Determining the type of roof: cold or warm?

And now about the concept of the attic. If you are building a roof for a bathhouse or a small utility room, it can be done using the most simplified technology - install rafters, connect them at the ridge and cover them with sheets of roofing felt. But for the roof of a residential building, where ventilation is important, this principle cannot be used. There will already be at least three levels:

The upper or first level of the rafters is about 200 mm.
The average one is always equal in height to the auxiliary rafters.
The third one is already on the edge of the wall.

This makes it convenient to install insulation, because the roof of a residential building is characterized by the fact that heat rises upward and, in the absence of thermal insulation, the roof covering is constantly heated.

The result: in winter, the snow melts and slides down, freezing and accumulating even more at the cold cornice. This causes a lot of problems: long dangerous icicles, a clogged drainage system, and the gradual destruction of the entire roof. Decide for yourself!

Determine the type of rafter system: layered or hanging?

So, now is the time to think about the support bases for future rafters, which also need to be prepared in advance and on which many parameters of the roof itself will depend. Thus, rafters are divided into layered, hanging and hybrid.

Hanging rafters are usually the lot of small and light roofs, the distance between the supports does not exceed 6 meters. But in buildings with a load-bearing middle wall or additional supports, layered rafters are installed to strengthen the roof. Or this combined option:

Another difference is that the hanging rafter system forces the Mauerlat to work in compression, while the layered rafter system works for shear. But the main task of both layered and hanging rafters is to transfer the loads of the entire roof to the walls and foundation as evenly as possible.

Selecting material for rafters

So, if you have decided on future loads, it’s time to choose the right material. The following are usually used for making rafters:

Wood. Solid wood, boards or laminated veneer lumber.
Lightweight metallic profile. We are talking about galvanized steel profiles.
Black metal. These are I-beams and steel channels.
Heavy reinforced concrete structures for industrial construction.

Dry board: economical option

If large loads are not expected on the rafter system, then make the rafters from dry planed boards with a small cross-section. But if knee-deep snow is not uncommon in your area and roofing material will not be easy - then some of constituent elements you will have to make glued ones. That's the whole difference.

It is most convenient to make elongated side rafters and diagonal rafter legs from the board. So, a board 40 mm thick, which is often used for outbuildings, not suitable for the roof. At least 50 mm! Moreover, the longer the rafter leg is planned, the wider the board itself should be. So, rafters 6 meters long will have to be made from boards 150 mm wide, and even longer ones - from boards 180 mm wide.

For the roof frame house this is truly one of the most best options!

And also rafters made from boards are the most economical, and at the same time they are almost as strong as lumber. It is only important to choose the right section and use quality material. Therefore, when purchasing material, be sure to take with you a special device for measuring wood moisture content and use it. There is nothing worse than damp rafters. And it’s not just a matter of future mold: such a roof will begin to warp and warp, because this material changes its shape when it dries. The fastenings at the rafters will fly off and even the covering of your gable roof will bounce off in places. In a word, there will be no problems!

But it is most convenient to splice rafters along the length from a regular board:

Durable metal: resists moisture

And, you will be interested to know that rafters can be made not only from wood! Thus, iron rafter systems, which were once used exclusively for industrial construction, are regaining their former popularity today. And, let us note, this roofing material has many advantages, the most valuable of which is the complete absence of fungus from dampness. After all, the space under the roof most often “pleases” with random leaks.

And the work itself with such rafters during installation is no more difficult than with wooden ones - see for yourself:

Beams: the benefits of high-quality wood

The timber is more durable, but the disadvantage is that it has a lot of weight and you have to make cuts at the fastening points. For a log this is not only a problem, but also some loss of the load-bearing capacity of such a rafter leg. But so far this material is the most popular for making rafters.

Most suitable for the manufacture of rafters is lumber that meets the requirements of GOST 8486-86 or 2695-83. And this:

Humidity no more than 18%, measured with a moisture meter.
Cracks that are not through and do not exceed half the length of the board.
For each linear meter– no more than three knots, and each of them is no more than 30 mm in diameter.

Therefore, when purchasing wood for rafters, be sure to check the documents from the seller, which indicate the quality of the product.

The type of wood is also important. The fewer knots and cracks there are on the beams, the better. Some varieties also boast good moisture resistance and resistance to rot and pests. For the roof this is what you need. Therefore, we recommend making rafters from coniferous wood, which is rich in resin, and resin is a natural barrier against rotting. But special processing is still needed.

And also take into account this fact: when manufacturing a rafter system, you need to purchase 5-7% more material than necessary, because it will not always be possible to make an ideal rafter cut or notch of the required depth. There will still be overspending, so stock up on it in advance so that you have wood of the same moisture content and properties for the entire rafter system.

Otherwise, if you had to purchase some individual roof elements separately, they may take longer to dry (wood always dries), or vice versa. The distortions can be considerable, i.e. the entire roof frame will be constantly exposed to different physical forces of tension and pressure. Any experienced roofer will tell you how bad this is and what it entails. Therefore, take more material for making rafters than you plan. If everything goes smoothly, there will be something to use to make the first bench in front of the new house.

Treatment with antiseptics and propylents

And at this stage it is already important to protect the future rafter system from biological destruction. You don’t want your roof to collapse after a couple of years of use, do you? Therefore, be sure to treat the wood for the rafters with fire and bioprotection.

The rafters are usually impregnated with an antiseptic and then treated with a fire retardant on top. You can also alternate this processing several times. If you use universal impregnation, be aware that it usually contains products with different service life. For example, fire protection will end before bio.

But the choice of means for processing today is huge. These include universal protective agents, a variety of fire retardants, and antiseptics. It’s easy to decide: if you are building in a fairly hot and dry area, first of all use fireproofing impregnations, which deprive the wood of its natural flammability. And if your house will be located where the air humidity is high almost all year round, protect it from rotting.

You can, of course, use both drugs - but just do not mix, otherwise the whole material will deteriorate. You just need to choose one product as an impregnation, and the second as a protective surface layer. Just try to dilute everything in the concentration indicated by the manufacturer. But do not treat frozen or damp wood with anything: its fibers simply will not absorb anything.

Video tip on the topic of processing rafters:

Note that a brush or spray when processing rafters gives little result - complete immersion and subsequent drying are much better. Just use a regular container, cover it with film from the inside and make a “bathtub” for future rafters. Moreover, it is advisable to do all this on the ground, as soon as you bring the material to the site, because in the finished rafter system it will be difficult to reach the internal elements of the connections. And they are the most defenseless in terms of moisture penetration. After processing, dry the parts so that all sides are ventilated for at least 24 hours.

Do not forget also that wood, like any natural material, subject to biological destruction. Therefore, in addition to fire-bio-protection, it is important to consider waterproofing in all places where the rafter system adjoins brick walls at home, if any.

Making the correct cuts on the rafters

Now let's move on to practice. First of all, you definitely need to make a convenient template according to which you will make even, identical rafters:

And follow these instructions:

You will have to tinker with the rigid mount:

If we're talking about about moving parts, then follow this principle:

In practice, everything is actually simple:

As you can see, the eyes are afraid, but the hands do!

How to assemble a rafter system?

Finally, the rafters are ready, and you can start installing them.

Build on the ground or on the roof?

So, in reality, everything is quite simple and somewhat similar to a children's construction set. The easiest and most convenient way is to make trusses directly on the ground, and only then raise them. It is a little more difficult to assemble the rafters directly on the roof, but it is easier to lift them there. This is where you start: if you have the opportunity (a crane, for example) to drag 200 kg of one truss onto the roof - drag it, if not - lift each individual rafter 50 kg using improvised means and do the assembly on the spot.

So, first of all, for convenience, make a template according to which you will assemble roof trusses, and another template for mounting cuts on the rafters (use plywood). All you have to do is cut out mounting cuts on the rafters, attaching a template, and connect them together at a certain angle. This triangle is called a roof truss.

Attention to strength - rules for increasing length

If the thickness or length of the board is not enough to make a normal rafter leg, extend the rafters. And there are several ways:

Connect the boards together by folding them with their wide sides and stitching them with nails.
Lay the boards half the length, resulting in a particularly strong rafter leg that can withstand considerable loads.
Make an oblique cut at the ends to create a vertical anti-slip stop, and connect with a bolt.
Lay two overlapping boards a meter long, connecting the rafters with pins or nails.

Also keep in mind when calculating that the roof ridge accounts for about 50% of the load of the entire rafter system. Therefore, always make a ridge beam so that its safety margin is at least 25% greater than originally calculated.

And the most vulnerable parts truss structures- lower ones, those that rest on the Mauerlat.

Preparing roof trusses

You need to secure the rafters using:

External straight bracket.
Metal corner plate.
Internal metal rod.

You can also connect such rafters with studs - this will even be stronger. To do this, instead of making a cut, we now make a cut into half the tree and connect the rafters with a ledge. Next, drill a hole for a 12-14 mm stud and secure it with nuts and wide washers.

Let's start with a review of proven old-fashioned methods:

Here's how they work:

When assembling a roof truss hanging type you need to connect the upper ends of the rafter legs. To do this, cut the end of each at exactly the same angle at which you are making the roof, connect the beams with cut planes and secure with two nails. Cover the joint with a wooden cover or metal plate.

Another useful master class:

Lifting and installation of finished trusses

Already on the roof, first of all, you need to start by installing those rafters that form the two outer trusses of the gable roof (they are also called gable). To further secure them, install temporary struts. Next, stretch a strong cord between the outermost peaks of the trusses, which will become a level for the intermediate rafters.

Now we lift and place all the remaining trusses at a distance of at least 0.6 meters from each other. Again, if some of your structures turn out to be quite cumbersome, support them with the same temporary supports.

The rest is a matter of technique: