Knots of a gable roof. Do-it-yourself installation of gable roof rafters: step-by-step process for installing rafters on the Mauerlat

Gable roofs are used for various wooden houses. You can even assemble the structure with your own hands, since it is simple, unlike a hipped or attic one. The main building materials for installation are boards and beams made of timber or logs. After reading the article to the end, readers will learn what the main elements of a gable roof frame are, and how to assemble it with your own hands and calculate the cross-section and length of the beams. About.

The rafter system of a gable roof for the construction of a house made of timber consists of: a rafter leg, a mauerlat, a filly, a ridge, struts, racks and sheathing. In order to assemble it with your own hands, you need to imagine the entire structure. We'll talk more about each element below.

Mauerlat

Mauerlat is the main load-bearing part of the gable roof frame structure. It consists of timber located around the entire perimeter of the house, on load-bearing walls. For the construction of a house from laminated veneer lumber or other type of lumber, it is secured using ties and metal brackets.

Through the Mauerlat, the load from the entire rafter system is transferred to load-bearing walls Houses. Mauerlat size for wooden house 100x100 mm or 150x150 mm will do. Coniferous wood is used for this unit. Before laying, the timber is treated with an antiseptic and waterproofed using bitumen tape.

Rafter leg

The main contour of the future roof is assembled from the rafter legs. For the roof frame of a wooden house, material with a cross section of 50x150 or 100x150 mm is used. The rafter legs are laid in the shape of a triangle. The entire system rests on the rafter legs, and whether the roof can withstand wind and snow loads depends on the quality of the material.

The weight of the entire roof structure is transferred through the legs to the Mauerlat. The rafter legs are mounted in increments of 60-120 cm, depending on the weight and fastening of the future roof. The heavier it is, the more frequent the installation step of the legs of the rafter system.

Horse

A ridge is a connecting beam between two rafter parts slope at the top. It is mounted strictly horizontally at the joint of the legs.

For a wooden gable roof, a beam with a section of 100x100 mm is used as a ridge. It is pre-treated with an antiseptic.

filly

The filly is an element that plays the role of a roof overhang. This part is attached to rafter leg, if its length is not enough to form an overhang of at least 200 mm. If the rafter leg is enough, then you don’t have to mount the filly.

For installation, boards of a smaller size and cross-section than the legs are used. The filly makes installation of the frame easier, since the beams for the legs no longer need a long length. If you assemble the roof yourself, then experts recommend choosing this option.

Sill

This is a beam that is placed horizontally on the internal load-bearing walls of the log house. The beam bears the main load from the racks of the rafter system, and it transfers it to the load-bearing wall.

The installation uses material with a cross-section of 100x100-150x150 mm.

Racks

The drains are attached vertically from the ridge to the internal load-bearing wall. For their manufacture, material with a cross section of 100x100-150x150 mm is used after calculations. In the rafter system, they play the role of redistributing the load from the ridge to the load-bearing wall.

Puffs

The ties connected to the legs of the frame have the shape of a triangle. This fastener in system. It is thanks to the tightening that the legs do not run apart different sides under the pressure of the structure and roof.

Struts

The struts consist of pieces of boards mounted at an angle. With the help of struts, the load from the rafter legs is redistributed to the load-bearing walls. In connection with the tie rods, the struts form trusses. The truss consists of several struts and one tie. Trusses are used to transfer the load if the spans are too large.

Lathing

Roof sheathing device

They make the sheathing from boards or thin bars. In the rafter system, the sheathing is attached perpendicular to the legs. With the help of lathing, the load from the roofing structure (roofing, insulation, vapor barrier -) is evenly distributed over all rafter legs. Another function of the lathing is to connect the rafter legs together in unified system. Not even suitable as a sheathing edged board. But first you need to peel off the bark from it.

If the roof is rolled, for example bitumen, then instead of boards, plywood sheets are used as sheathing. This way the roofing substrate acquires a hard and even surface, on which it is easy to roll out the same roofing material.

All of the listed parts of the frame of the gable structure are dried and treated before installation. antiseptic impregnations, you can do this yourself. Otherwise, the rafter system will quickly rot.

What kind of rafter system is there for a gable roof?

The rafter contraction for a gable roof for the construction of a house made of profiled timber can be used suspended or suspended.

Hanging structure

This system has a structure based on the side load-bearing walls of the log house. But at the same time, the rafters negatively interact with the walls, pushing them apart. To avoid this, in the frame of a gable roof the legs are tightened with special ties. The ties and legs form a triangular mount, which has rigid ribs, and the structure does not deform over time.

IN truss structure The role of tightening can be played by floor beams. This way the structure can be used as an attic. For greater strength, a tightening is also installed on top of the rafter part at least 50 cm from the roof ridge.

It is necessary to make such a design if the span between the load-bearing walls of the log house is no more than 10 cm. If this span is larger and there is a load-bearing wall between it that divides it in half, then a hanging system can be installed

Layered structures

The layered rafter system is installed on a log house with any span. Its peculiarity is the support beam, which is located in the middle of the wall span. It is advisable to use such a design when the distance between load-bearing walls is more than 10 m.

If there is a load-bearing column between the main load-bearing walls, then you can use the attic version of layered rafters. In this case, the rafters will be attached to the column, and additional rafters will be made between the columns. But doing it without certain skills is difficult.

How to calculate roof rafters

Before you start making a roof frame with your own hands, you need to calculate the length and thickness of the beams.

Calculation of beam sections

The cross-section of rafter beams is directly related to their length and fastening pitch. To determine the ratio of these indicators, there are special calculators with which it is not difficult to make calculations and GOST standards.

Calculation of the ratio of the length and cross-section of beams in the form of a table:

Rafter beam length, m	Section of the material used, mm		Rafter pitch, m
	Beam or board	Log
From 1-3	80x100, 90x100, 90x160	100, 150, 160	1 – 1,35
From 3-4	80x160, 80x180, 90x180	160, 180	1,40 – 1,70
From 4-5	80x200, 100x200	200	1,40 – 1,75
From 5-5.8	100x200	200	1,10 – 1,40
From 5.9-6.5	120x220	240	1,10 – 1,40

Judging by the numbers, if the length of the rafters is large, then the distance between them decreases and the cross-section increases. If you take rafters of a smaller cross-section and do not make the necessary calculations, then over the years the roof will sag.

After the calculation has been made, you need to saw off the leg beams to the same length and mount each pair on that straight line.

Subtleties of installing a gable roof

The main stages of building a roof frame with your own hands consist of:

1. Mounting the Mauerlat
2. Installation of rafter legs
3. Ridge installation
4. Bunch of legs
5. Lathing

How professionals install a roof can be seen in the video provided:

In the video you can see the finished frame made of timber and its description, each node clearly. Readers will find in the video the mauerlat, rafter legs, their fastening, etc.

Mauerlat fastening

IN wooden houses There is no need to mount an additional Mauerlat. Its role will be played by the top log or timber. But if the roof structure should be higher, then the timber must be tied.

The laying of the timber begins with its insulation; for this, the walls are covered with a double layer of roofing material on top. The timber is processed and laid. In the corners it is connected with your own hands using metal staples and half-section cuts.

The Mauerlat is placed strictly parallel to the opposite wall so that the rafter legs are subsequently identical.

More details on how to attach the rafters to the Mauerlat can be seen in the video below:

The video clearly shows how the fastening of legs - beams to beams should look like from professionals.

Installation of rafter legs

For the exact location of the rafter legs, pencil and meter marks are made on the mauerlat. But before this, it is necessary to draw up a diagram or calculation of their location.

The preparation of the rafter legs begins with a cut from the bottom side, 1/3 of the width is made. Their leg will rest on the mauerlat. The option of their fastening depends on what material the rafters will be made of.

The slope of the future roof will depend on the angle at which the leg beams are secured. It should not be made very flat and steep. It is better to first make a calculation according to the regional indicators. If wind loads are high in the area where you live, then the angle cannot be more than 20°C. At high precipitation rates, the slope is made at 35-40°C. This way, snow and precipitation will not accumulate, and the roof will begin to clean itself.

In the upper part, the rafter legs are connected to the ridge using iron brackets into a single structure.

Bundle of rafter legs in a hanging structure

Beams - legs are assembled together before their installation. The connecting elements can be bolts or nuts with iron plates. After completing the collection of triangular fasteners with rafter legs, they begin to install from the two outer ones. Then the next two are installed. The frame needs to be fixed with temporary jibs. At the end of installation they are removed.

After the legs are fully installed, the fillies are attached to them. The size of the overhang of the future roof will depend on their length. For a wooden house, this distance is taken as maximum to prevent water from getting on the walls.

Installation of rafters in a layered structure

With this installation, the rafters begin to be mounted from a laying on which two supports are installed. A ridge beam is mounted on top of the supports. The jibs provide additional rigidity to the structure.

The rafter legs are attached to the ridge beam. If you take the length of the rafter legs a little longer and file them with a circular saw after twisting, then the work will be more productive.

Installation of sheathing

After the installation of the rafter legs is completed, they begin to attach the sheathing. In this case, marking begins from the ridge, where two massive wide boards are first mounted.

The sheathing must be installed along the entire length of the gable roof in increments of a certain roof.

When the rafter system is completely assembled, the overhang and gables of the roof are sewn up. After this, the roofing material is laid and the structure is insulated. We talked about how to properly insulate a roof HERE.

As you can see from the article, it’s not difficult to do the work yourself, and by imagining what the structure of a gable roof looks like, you can easily make a plan and calculation for your log house. It is advisable to choose the best and highest quality material that will be used during installation.

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

The gable roof consists of two inclined surfaces that have a 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 square section- from 100 by 100 to 150 by 150 mm. It is 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 settling in soft roof to create the sheathing, you should not use boards and bars, but moisture-resistant plywood.

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 the outer 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 himself. roofing, 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 quality protection roofing covering.
• 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 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 assume a snow load of 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 best materials as materials. quality wood. Beams that have cracks and knots should absolutely not be used.
2. The rafters have standard dimensions - 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 light, install 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 will not be able to provide high-quality fastening, since the 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 gable roof rafter system, you can begin installation roofing pie. Place thermal insulation material, a layer of vapor barrier and waterproofing between the rafters. When using insulation in slabs, calculate in advance the pitch of the rafters for its installation. At the final stage, attach the roofing material.

Thanks to simple device, 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 further operation attic space. There are three main types of gable roof:

• Symmetrical. The most common option provides a reliable device and uniform load distribution. There is virtually no risk of rafters bending down. Significant disadvantage- impossibility of arranging an attic. Sharp corners form areas of the attic that are unusable.
• Simple asymmetrical. The formation of one angle exceeding 45 o provides an increase 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 the non-standard design, it becomes possible to use the attic space to create a full second floor. Calculations for installing rafters become much more complicated.

Calculate correct angle slope is a key task preceding the installation of 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

The Mauerlat and rafter system are the load-bearing elements of a gable structure. 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, additional installation of diagonal struts is performed;
• spacers;
• bed and sheathing.

Advice ! The rafter diagram necessarily includes the installation chimney and 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 at the bottom allows them to perform the function load-bearing beams. An indispensable condition is reliable fixation of the tightening, as 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 two pitched roofs provide for the installation of combined rafters.

Having determined suitable look rafter system, proceed to calculating the amount of material. Moreover, each roof element needs separate drawing and recording 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. At the 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 the magnitude of permanent loads - the 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 winds. To calculate this parameter, we turn to the indicators specified in SNiP “Loads and Impacts”, taking into account related factors (location of the house in 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. When using a 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 the 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

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. Secure fastening- 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 the assembled elements onto the roof. The installation of 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 wooden structure. Mounting options are shown below:

To install paired rafters, temporary spacers and struts are used. The ridge unit is formed by connecting 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.

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, absorb atmospheric loads, and hold the material. Among the rafter's duties are the formation of smooth planes for laying the covering and providing space for the components of the roofing pie.

In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information is needed about the rules and principles of its design. The information is useful both for those who are constructing a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

In the construction of the rafter frame for pitched roofs, wooden and metal beams. The starting material for the first option is a board, log, timber.

The second is constructed from rolled metal: channel, profile pipe, I-beam, corner. There are combined structures with the most heavily loaded steel parts and wood elements in less critical areas.

In addition to its “iron” strength, metal has many disadvantages. These include thermal qualities that are unsatisfactory to the owners of residential buildings. The need to use welded joints is disappointing. Most often, industrial buildings are equipped with steel rafters, and less often, private cabins assembled from metal modules.

In the matter of independent construction of rafter structures for private houses, wood is a priority. It is not difficult to work with, it is lighter, “warmer”, and more attractive in terms of environmental criteria. In addition, to make nodal connections you will not need a welding machine or welder skills.

Rafters - a fundamental element

The main “player” of the frame for constructing a roof is the rafter, which among roofers is called a rafter leg. Beams, braces, headstocks, purlins, ties, even a Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

Rafters used in the construction of gable roof frames are divided into:

• Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests against the mauerlat or the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of the adjacent rafter or a purlin, which is a beam laid horizontally under the ridge. In the first case, the rafter system is called spacer, in the second, non-spacer.
• Hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - a tie. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a rafter truss. Tightening dampens the tensile processes, so that only vertically directed load acts on the walls. Although a structure with hanging rafters is braced, the bracing itself does not transmit to the walls.

In accordance with the technological specifics of rafter legs, the structures constructed from them are divided into layered and hanging. For stability, the structures are equipped with struts and additional racks.

To support the top of the layered rafters, planks and purlins are installed. In reality, the rafter structure is much more complex than the elementary templates described.

Note that the formation of the frame of a gable roof can generally be done without a rafter structure. In such situations, the supposed planes of the slopes are formed by slabs - beams laid directly on the load-bearing gables.

However, we are now interested specifically in the structure of the rafter system gable roof, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

Fastening the rafter system to brick, foam concrete, aerated concrete walls is carried out through the Mauerlat, which in turn is fixed with anchors.

Between the Mauerlat, which is a wooden frame, and the walls made of the specified materials, a waterproofing layer made of roofing felt, waterproofing material, etc. is required.

The top of brick walls is sometimes specially laid out so that along the outer perimeter there is something like a low parapet. This is so that the mauerlat placed inside the parapet and the walls do not push apart the rafter legs.

The rafters of the roof frame of wooden houses rest on the upper crown or on ceiling beams. The connection in all cases is made by notches and is duplicated with nails, bolts, metal or wooden plates.

How to do without mind-boggling calculations?

It is highly desirable that the cross-section and linear dimensions of wooden beams be determined by the project. The designer will provide clear calculation justification for the geometric parameters of the board or beam, taking into account the entire range of loads and weather conditions. If available home handyman design development no, his path lies to the construction site of a house with a similar roofing structure.

You don’t have to pay attention to the number of floors of the building being constructed. It is easier and more correct to find out the required dimensions from the foreman than to find out them from the owners of a shaky self-built building. After all, in the hands of the foreman is documentation with a clear calculation of the loads per 1 m² of roof in a specific region.

The installation pitch of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For styling clay tiles, For example, optimal distance between the rafters there will be 0.6-0.7 m, and for corrugated sheets 1.5-2.0 m is acceptable.

However, even if the pitch required for proper installation of the roof is exceeded, there is a way out. This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to understand the pitch of the rafters before constructing the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, simply dividing the length of the slope into equal distances. For insulated roofs, the pitch between the rafters is selected based on the width of the insulation slabs.

You can find it on our website, which may also help you a lot during construction.

Rafter structures of layered type

Layered rafter structures are much simpler to construct than their hanging counterparts. A reasonable advantage of the layered scheme is to ensure adequate ventilation, which is directly related to long-term service.

Distinctive design features:

• It is mandatory to have support under the ridge heel of the rafter leg. The role of support can be played by a purlin - a wooden beam resting on posts or on the internal wall of the building, or the upper end of an adjacent rafter.
• Using a Mauerlat to erect a truss structure on walls made of brick or artificial stone.
• The use of additional purlins and racks where rafter legs are required due to the large size of the roof additional points supports.

The disadvantage of the scheme is the presence structural elements, affecting the layout of the internal space of the used attic.

If the attic is cold and organization is not expected in it useful premises, then the layered structure of the rafter system for installing a gable roof should be given preference.

Typical sequence of work for the construction of a layered truss structure:

• First of all, we measure the heights of the building, the diagonals and horizontality of the upper cut of the frame. When identifying vertical deviations of brick and concrete walls, we remove them with a cement-sand screed. Exceeding the heights of the log house is cut off. By placing wood chips under the mauerlat, vertical flaws can be combated if their size is insignificant.
• The floor surface for laying the bed must also be leveled. It, the Mauerlat and the girder must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
• We treat all wooden parts of the structure with fire retardants and antiseptics before installation.
• On concrete and brick walls We lay waterproofing under the installation of the Mauerlat.
• We lay the mauerlat beam on the walls and measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the ideal geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The beams are joined into a single frame using oblique notches; the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fastening is done either with staples to wooden plugs placed in the wall ahead of time, or anchor bolts.
• Mark the position of the prone position. Its axis should recede from the mauerlat bars at equal distances on each side. If the run will rest only on posts without supports, we carry out the marking procedure only for these posts.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, with internal wall We connect with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut out the racks to uniform sizes, because... Our bed is exposed to the horizon. The height of the racks should take into account the cross-sectional dimensions of the purlin and beam.
• We install racks. If provided by the design, we secure them with spacers.
• We lay the purlin on the racks. We check the geometry again, then install brackets, metal plates, and wooden mounting plates.
• We install a test rafter board and mark the cutting areas on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the rafters on the roof after the fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. For marking, folk craftsmen usually prepare a pair of slats, the length of which is equal to the clearance between the rafters.
• According to the markings, we install the rafter legs and fasten them first at the bottom to the mauerlat, then at the top to the purlin to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is made flawlessly, the layer boards are installed in any order.

If there is no confidence in the ideal structure, then the outer pairs of rafters are installed first. A control string or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the rafter structure is completed by installing fillets, if the length of the rafter legs does not allow forming an overhang of the required length. By the way, for wooden buildings the overhang should extend beyond the contour of the building by 50 cm. If you plan to organize a canopy, separate mini-rafters are installed under it.

Another useful video about building a gable rafter base with your own hands:

Hanging rafter systems

The hanging variety of rafter systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the base is the tie connecting the lower heels.

The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the sheathing, roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging rafter structures.

Specifics of hanging rafter systems

Characteristic features of hanging type rafter structures:

• The obligatory presence of a tie, most often made of wood, less often of metal.
• Possibility to refuse to use the Mauerlat. A timber frame can be successfully replaced by a board laid on double-layer waterproofing.
• Installation of ready-made closed triangles – trusses – on the walls.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages.

The first of them is restrictions on the steepness of the slopes: their slope angle can be at least 1/6 of the span of a triangular truss; steeper roofs are strongly recommended. The second disadvantage is the need for detailed calculations for the proper installation of cornice units.

Among other things, the angle of the truss will have to be installed with pinpoint precision, because the axes of the connected components of the hanging rafter system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the backing board replacing it.

Subtleties of long-span hanging systems

The tie is the longest element of a hanging rafter structure. Over time, as is typical for all lumber, it becomes deformed and sags under the influence of its own weight.

Owners of houses with spans of 3-5 meters are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional parts that exclude geometric changes in tightening.

To prevent sagging, there is a very significant component in the installation diagram of the rafter system for a long-span gable roof. This is a pendant called a grandmother.

Most often it is a block attached with wooden pegs to the top of the truss. The headstock should not be confused with the racks, because its lower part should not come into contact with the puff at all. And installation of racks as supports in hanging systems ah does not apply.

The bottom line is that the headstock hangs, as it were, on the ridge assembly, and a tightening is attached to it using bolts or nailed wooden plates. To correct sagging tightening, threaded or collet-type clamps are used.

The tightening position can be adjusted in the area of ​​the ridge assembly, and the headstock can be rigidly connected to it by a notch. Instead of a bar in non-residential attics, reinforcement can be used to make the described tension element. It is also recommended to install a headstock or hanger where the tie is assembled from two beams to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The stress forces in the resulting rhombus are extinguished spontaneously due to the proper placement of vector loads acting on the system.

As a result, the rafter system is stable with minor and not too expensive modernization.

Hanging type for attics

In order to increase the usable space, the tightening of the rafter triangles for the attic is moved closer to the ridge. A completely reasonable move has additional advantages: it allows you to use the puffs as a basis for lining the ceiling.

It is connected to the rafters by cutting with a half-pan and duplicating with a bolt. It is protected from sagging by installing a short headstock.

A noticeable disadvantage of the hanging attic structure is the need for accurate calculations. It is too difficult to calculate it yourself; it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of rafter systems cannot be the same, because:

• In the construction of a layered structure, a board or beam of small cross-section is used to make rafter legs. Because layered rafters have two reliable supports underneath them; the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, the rafters are made of thick timber. To make a tightening, a material with a similar cross-section is required. Even taking into account the abandonment of the Mauerlat, the consumption will be significantly higher.

It will not be possible to save on the grade of material. For load-bearing elements Both systems: rafters, purlins, planks, mauerlat, headstocks, racks require 2nd grade lumber.

For crossbars and tensile ties, grade 1 will be required. In the manufacture of less critical wooden overlays, grade 3 can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used in greater quantities.

Hanging trusses are assembled in an open area next to the facility, then transported, assembled, upstairs. To lift weighty triangular arches from timber, you will need equipment, the rental of which will have to be paid. And the project for complex nodes of the hanging version is also worth something.

Video instruction on the installation of a hanging category truss structure:

There are actually many more methods for constructing rafter systems for roofs with two slopes.

We have described only the basic varieties that are actually applicable for small country houses and buildings without architectural tricks. However, the information presented is enough to cope with the construction of a simple truss structure.

Thanks to its simple, reliable and presentable design, the gable roof has been popular for many years. Depending on the slope of the slopes, it is used in regions with varying amounts precipitation. The rafter system of the gable roof ensures natural precipitation.

1. Symmetrical - both slopes have the same length and are mounted at the same angle. Such a roof represents an isosceles triangle with an obtuse or acute angle.
2. A sloping roof is created to accommodate attic room, its rafter system implies a complex, two-level structure.
3. Different slope angles are original design, emphasizing the unusual architecture of the house.

Tilt angle value

The angle of inclination is selected after analyzing several indicators: type of roofing, amount of precipitation, wind load. For regions with heavy rainfall, a small slope angle is recommended, but not less than 5 degrees. Snow masses do not linger on steep surfaces. Flat roofs with obtuse slopes are suitable for windy climates.

The rafter system of a gable roof must comply accepted standards safety and be built according to standards.

Rafter systems

Load-bearing elements and rafters take on the load from external forces and redistribute it to the walls of the building. The strength of the entire roof depends on their reliability. When constructing the structure, two systems for constructing rafters are used:

• Hanging - rafter legs have two points of support on the walls of the building. They experience compression and bending loads. When the span exceeds 8 meters, a headstock with struts is required. To reduce the impact of the rafters on the walls of the building, they are connected by tightening.
• Layered - these beams are supported on an internal wall or a special structure.

If it is impossible to use one of the systems in its pure form, they resort to a hybrid design that allows alternating hanging and layered rafters.

The design of the rafter system of a gable roof allows you to carry out calculations yourself, relying on knowledge of geometry. To calculate the area of ​​the structure, you need to set the length of the slope. The amount of material required depends on the angle of inclination. A sharp angle saves money, but at the same time minimizes attic space.

We calculate the height of the ridge, the length of the rafters and the roof area using geometric formulas. Suitable for clarity scheme Houses. Example - let's take the slope angle of 45 degrees, the width of the house (the base of the isosceles triangle) is 6 m, the length is 10 m.

First we divide the triangle in half with the height lowered from top corner. That makes two right triangle, and one of the legs is the required roof height. The height divides the isosceles triangle in half, which means that one leg is 3 m. We calculate the second using the formula:

3 × tg 45 0 =3 m.

Knowing the legs, using the Pythagorean theorem we calculate the hypotenuse, which is the rafter:

3 2 + 3 2 = X 2.

The length of the rafter will be equal to the square root of 18, approximately 4.25

The number of rafters is calculated by dividing the total length by the pitch (0.6 m):

10: 0.6 = 16.6 – this value needs to be doubled.

We calculate the area by multiplying the length of the slope and the house and multiplying the value by 2:

4.25 × 10 × 2 = 85 m 2.

The load-bearing base for the roof is the mauerlat - a durable timber with a cross-section of 150×150 mm made from processed coniferous species tree. Its fastening is carried out on anchors walled up in the top row of the masonry. They should rise 2-3 cm above the beam to provide room for tightening the nut. A layer of roofing material is laid under the Mauerlat to protect it from moisture. A transverse beam is laid between the walls, fastening the Mauerlat and protecting it from longitudinal loads. To support the ridge, a special beam is laid along the slope - a bench, with a cross-section equal to the mauerlat. If the building is significant, it is necessary to install purlins.

The cross-section of the rafters is determined by the pitch and length of the rafter element, usually boards 50x150 mm. Roof trusses are easier to assemble on the ground and ready to go onto the roof. For the template, take two boards equal in length to the rafters and connect them with a nail. The free ends are placed on supports, and the resulting angle is fixed with a crossbar. The locations and shape of the cuts are marked using a second template made of plywood. The beams are bolted together at the desired angle, cuts are made on them, and after the truss they are lifted up for installation.

The rafters on the gables are installed first. They are attached to the Mauerlat using corners or staples. The first farms are set strictly according to level. A cord is stretched between them, which serves as a guide for installing the remaining elements.

To give sufficient rigidity to the entire structure, struts and crossbars are attached to the rafter leg. The ridge purlin is bolted to each truss. This connecting element must be made of durable timber.

With a significant building width, it is necessary to install purlins; this is a horizontal beam measuring 50x150 mm that supports the rafters. To install it, install vertical posts resting on the bench. These elements will form the basis of the frame for the attic space.

To avoid water flowing onto the walls, it is necessary to provide an overhang; for this, the rafters are made to hang down by 30 cm or additional “filly” boards are attached.

Lathing is placed on the finished rafters, and for each roofing material, the right step, For bitumen shingles continuous flooring is performed. Roof insulation is an important part of construction. Heat loss can be reduced to a minimum by properly installing insulation. For this purpose it is taken basalt wool, the width of the material is equal to the pitch between the rafters, which allows for quick and reliable insulation. Provide reliable protection The roof will be protected from moisture by installing waterproofing.

The symmetrical gable roof model is the easiest to construct and most reliable option. The load in the rafter system is distributed evenly, which allows you to extend the service life of the structure. Visual video lessons will help you master the intricacies of the work.

Video

This video explains how to build a gable roof truss system:

In this video you can see the rafter system using the example of one gable roof: