How to make a truss system with your own hands. Rafter system - varieties, load calculation, optimal designs and installation ideas (95 photos) Types of truss systems - how they differ from each other

Rafters serve as the basis of the entire roof structure, and their installation is one of the most important tasks in building a house. The frame of the future roof can be made and installed independently, observing the technological features of roofs of different configurations. We will give the basic rules for the development, calculation and selection of the truss system, and also describe in stages the process of installing the "skeleton" of the roof.

Rafter system: rules for calculation and development

The rafter system is a supporting structure that can resist gusts of wind, take on all external loads and evenly distribute them to the internal supports of the house.

When calculating the rafter structure, the following factors are taken into account:

1. Roof pitch:
   • 2.5-10% - flat roof;
   • more than 10% - pitched roof.
2. Roof loads:
   • constants - the total weight of all elements of the "roofing pie";
   • temporary - wind pressure, snow weight, weight of people who carry out repair work on the roof;
   • force majeure, for example, seismic.

The magnitude of snow loads is calculated based on the characteristics of the climate of the region according to the formula: S=Sg*m, where Sg- snow weight per 1 m2, m- calculation coefficient (depends on the slope of the roof). The determination of the wind load is based on the following indicators: type of terrain, wind load standards of the region, building height.

Coefficients, necessary standards and calculation formulas are contained in engineering and construction reference books

When developing a truss system, it is necessary to calculate the parameters of all components of the structure.

Roof structure elements

The truss system includes many components that perform a specific function:

Materials for the manufacture of rafters

Rafters are most often made from coniferous trees (spruce, larch or pine). For the arrangement of the roof, well-dried wood with a moisture level of up to 25% is used.

The wooden structure has one significant drawback - over time, the rafters can be deformed, so metal elements are added to the supporting system.

On the one hand, the metal adds rigidity to the truss structure, but on the other hand, it reduces the life of the wooden parts. Condensation settles on metal platforms and supports, which leads to decay and damage to the wood.

Advice. When installing a truss system made of metal and wood, care must be taken that the materials do not come into contact with each other. You can use moisture barriers or apply film insulation

In industrial construction, metal rafters made of rolled steel (I-beam, brand, corners, channel, etc.) are used. This design is more compact than wood, but retains heat worse, and therefore requires additional thermal insulation.

The choice of truss system: hanging and hinged structures

There are two types of roof structures: hanging (spacer) and layered. The choice of system is determined by the type of roof, floor material and natural conditions of the region.

hanging rafters rely solely on the outer walls of the house, intermediate supports are not involved. Hanging type rafter legs perform work on compression and bending. The design creates a horizontal bursting force that is transmitted to the walls. With the help of wooden and metal puffs, this load can be reduced. Puffs are mounted at the base of the rafters.

A hanging truss system is often used to create an attic or in situations where roof spans are 8-12 m, and additional supports are not provided.

Rafters mounted in houses with an intermediate column support or an additional load-bearing wall. The lower edges of the rafters are fixed on the outer walls, and their middle parts are fixed on the inner wall or bearing pillar.

Installation of a single roofing system over several spans should include expansion and layered roof trusses. In places with intermediate supports, layered rafters are mounted, and where they are not, hanging ones.

Features of the arrangement of rafters on different roofs

Gable roof

The gable roof, according to building codes, has an angle of inclination up to 90 °. The choice of slope is largely determined by the weather conditions of the area. In areas where heavy rainfall prevails, it is better to install steep slopes, and where strong winds prevail - gentle roofs in order to minimize pressure on the structure.

A common version of a gable roof is a design with an angle of inclination of 35-45 °. Experts call such parameters the "golden mean" of the consumption of building materials and the distribution of the load along the perimeter of the building. However, in this case, the attic will be cold and it will not be possible to equip the living room here.

For a gable roof, a layered and hanging truss system is used.

hipped roof

All roof slopes have the same area and the same angle of inclination. There is no ridge run here, and the rafters are connected at one point, so the installation of such a structure is quite complicated.

It is advisable to install a hipped roof when two conditions are met:

• the base of the building is square;
• in the center of the structure there is a bearing support or wall on which it will be possible to fix a rack supporting the junction of the rafter legs.

It is possible to create a hipped roof without a rack, but at the same time, the structure must be strengthened with additional modules - rack puffs.

hip roof

The traditional design of the hip roof assumes the presence of slanting rafters (diagonal) directed to the corners of the building. The angle of inclination of the slope of such a roof does not exceed 40 °. Diagonal runs are usually done with reinforcement, since they account for a significant part of the load. Such elements are made from a double board and a durable beam.

The joints of the elements are necessarily supported by a rack, which increases the reliability of the structure. The support is located at a distance of ¼ of the length of the large rafters from the ridge. In place of the gable roof gables, shortened rafters are installed.

The truss structure of a hipped roof may include very long diagonal elements (more than 7 m). In this case, a vertical rack must be mounted under the rafters, which will rest on the floor beam. Sprengel can be used as a support - the beam is located in the corner of the roof and is fixed on adjacent walls. The sprengel farm is reinforced with struts.

broken roof

Sloping roofs are usually created to equip a larger attic. The installation of rafters with this version of the roof can be divided into three stages:

1. Installation of a U-shaped structure - supports for purlins that hold the rafter legs. The base of the structure is floor beams.
2. At least 3 runs are installed: two elements pass through the corners of the U-shaped frame, and one (ridge run) is mounted in the center of the attic floor.
3. Installation of rafter legs.

Gable roof: do-it-yourself installation of rafters

Calculation of the angle of inclination and loads

The calculation of a gable roof, of course, can be done independently, but it is still better to entrust it to professionals in order to eliminate errors and be sure of the reliability of the structure.

When choosing the angle of inclination, it is necessary to take into account that:

• an angle of 5-15 ° is not suitable for all roofing materials, so first choose the type of coating, and then make the calculation of the truss system;
• at an angle of inclination over 45 ° - material costs for the purchase of the components of the "roofing pie" increase.

Snow load limits range from 80 to 320 kg/m2. The design coefficient for roofs with a slope of less than 25 ° is 1, for a roof with a slope of 25 ° to 60 ° - 0.7. This means that if 140 kg of snow cover falls on 1 m2, then the load on the roof with a slope at an angle of 40 ° will be: 140 * 0.7 = 98 kg / m2.

To calculate the wind load, the coefficient of aerodynamic influence and wind pressure fluctuations are taken. The value of the constant load is determined by summing the weight of all components of the "roofing pie" per m2 (on average - 40-50 kg/m2).

Based on the results obtained, we find out the total load on the roof and determine the number of rafter legs, their size and cross section.

Installation of Mauerlat and rafters

Do-it-yourself installation of rafters begins with the installation of a Mauerlat, which is fixed with anchor bolts to the longitudinal walls.

Further construction of the structure is carried out in the following sequence:

Installation of rafters: video

Ways to connect the elements of the truss structure: video

The roof is a complex and important architectural element of any building. Its construction should be treated with special attention, it must be remembered that the installation of a truss system requires considerable experience in performing such work and a special tool. It is not worth taking on the creation of a roof for those who hold a carpentry and measuring tool in their hands for the first time - the results of the activity can be very negative.

There are two types of roofs, depending on the number and placement of rafter support points, but each developer can, at his own discretion, slightly change the specific design of the truss system. This takes into account the operating conditions of the building, the purpose of the attic space, the climatic zone of the location, the technical parameters of lumber and roofing. Of course, the type of truss system is influenced by the personal experience and preferences of developers.

Before proceeding with the manufacture of rafters, you should decide on their type, method of fastening and linear dimensions. Only in this case, you can be sure of the strength and safety of the structure.

How do various factors affect the parameters of the rafters?

physical factor	Brief description of the influence on the parameters of the rafters
	Rafters must withstand snow and wind loads. During the calculations, it is necessary to take the actual maximum values ​​​​of snow cover from the tables of building codes and rules, take into account the strength and rose of the winds. The data allows you to find out the total load on the roof slope, depending on its area and angle of inclination. Further, it is already possible to determine the dimensions of the rafters, their number and step. In this case, a safety factor is necessarily laid down. The fact is that lumber does not have stable and identical strength values, too many unforeseen factors affect these indicators. For most cases, 50 × 150 mm or 50 × 200 mm boards are used for the manufacture of rafter legs.
	Gable roofs can be layered and hanging. For hanging roofs, you need to make rafters from more durable boards. This takes into account the method of fixing the elements to the Mauerlat. If a cut is made, then the width of the boards should increase by the size of the cut. The fact is that the cut in this place automatically reduces the width of the material that receives the load. If a cross cut 60 mm long is made on a board with a thickness of 200 mm, then only the remaining width of 140 mm is taken into account. Accordingly, if rafters from 200 mm boards are selected when calculating loads, but unforeseen cuts of 60 mm are made during fastening, then the width of the blanks for rafters increases to 260 mm. This remark is made for those who like to abuse various notches and cuts for the thrust areas of the ends of the rafters. Currently, there are many special devices that allow you to firmly fix the rafter in the desired position without sawing.
	For residential buildings, rafters must have a safety margin of at least 1.4 of the calculated values. For non-residential structures, the coefficient is reduced to 1.2. Conclusion - the dimensions of the rafters on the houses are larger than on garages and other outbuildings.
	Residential attics (mansards) must have an insulated roof. The width of the rafters must correspond to the thickness of the insulation layer. At the same time, it is necessary to adjust the step between the rafter legs, depending on the standard width of the insulation. If in this climatic zone the optimal thickness of the roof insulation is 200 mm, then it is recommended to choose the same width for rafters. Various extensions of narrow rafter legs during roof insulation are not considered the right solution.

This knowledge will help you make the right decisions both during the manufacture of rafters and during their fixation directly in place. Mistakes in the construction of the truss system are too expensive, you should not show excessive self-confidence.

What influences the choicesizes andwaysmountsrafter

A very important point. The task of any fixation is to ensure the stability of the connection node, while it can be fixed or have one or more degrees of freedom. This cannot be achieved without knowledge of the loads affecting the rafter legs. Loads can be permanent and temporary, dynamic and static, unidirectional and multidirectional.

1. Constant vertical forces. Arise due to the impact of roofing and roof insulation materials. Due to the fact that the rafter legs are located at an angle to the vertical force, they are subject to bending and bursting loads. The magnitude of the forces is determined after the construction of the diagram, on the basis of specific bending and bursting forces, the thickness and width of the boards for the rafters are selected. Fasteners must prevent the spreading of the truss system.
2. Variable vertical forces. Appear in winter, the value depends on the height of the snow cover.
3. Lifting wind forces. As a result of gusts of wind, lifting forces act on the roof. They do not affect the dimensions of the rafter legs, efforts are taken into account only when choosing the type of fixation, it must provide for and hold such loads.
4. Lateral efforts. The value depends on the windage of the roof. As a result of gusts of wind, lateral forces act on the truss system. They increase bending and tearing loads. This feature must also be taken into account during the manufacture and installation of rafter legs.

There are options for rigid fastenings of truss trusses; for this, metal plates, corners, self-tapping screws and nails are used.

Sometimes it is required to use floating rafter connections to compensate for changes in the size of wooden houses. For floating connections, special fasteners and bolts are used. The second allows the rafter legs at the top to turn a little.

Another example of a free rafter connection is a sliding one. It is used on wooden log cabins and makes it possible to compensate for the natural shrinkage of the house.

What elements are used to increase the stability and bearing capacity of the rafters

As a result of the correct choice of the truss system and methods of fixing its elements, the structure must be stable, compensate for natural fluctuations in linear parameters and withstand various loads that occur during operation. To fulfill the conditions during the fixation of the rafters, additional fixation elements can be used.

Runs

Most often they are mounted in the ridge part of the system, the upper ends of the rafter legs rest on them. To increase stability, cuts may be provided. The top connection is rigid or floating on bolts. On large roofs, girders can be installed in the middle of the rafter legs or in other places with critical loads.

vertikaflax racks

They are installed to strengthen the rafters; due to the use of racks, elements can be made from thinner lumber. Vertical racks with their upper end abut against the rafters, and with their lower end against the bed or ceiling beams.

corneraboutpores

Retain bending and expansion forces, universal use. Corner stops can be placed in any places of the rafter leg that cause concerns about strength. Due to such stops, the resistance of the rafters to bending and tearing forces is significantly increased.

Puffs(crossbars)

Purpose - to keep the rafter legs from sprawling, they are used on hanging rafter systems. Most often they are placed in the upper part of the truss; boards with a thickness of about 20–25 mm can be used for manufacturing. The fact is that they work in tension, lumber holds such efforts well. Boards do not work well in compression, quickly bend and lose their original strength indicators.

Knuckleadki

They are used in the upper ridge part of the rafters, due to the use of puffs, the strength of the knot connection increases. Puffs can be made of wood, plywood, OSB or metal.

Bosses(stops)

They have many specific names. They are ordinary pieces of boards 30–40 cm long and 40–50 mm thick, fixed at the bottom of the rafters. They rest against the Mauerlat and do not allow the structure to slip. The use of bosses allows you to perform a rigid connection of elements without sawing the rafters. We talked about the problems that arise in connection with sawing in this article above.

Prices for various types of timber

Options for connecting the ridge knot of the rafter legs

The horse is one of the main and most loaded elements of the truss system. The node has several connection options, you should choose a specific one depending on the general parameters of the roof.

With a large length of slopes, it is better not to use a ridge beam, but instead to put two parallel runs and puff crossbars. This design is easier to do, it is more stable and safe.

For a hanging roof, you should choose the most reliable ways to connect the rafter legs, these systems have a minimum number of additional stops.

Prices for various types of fasteners for rafters

Fasteners for rafters

step by stepwithtruction of the mouthanew rafters

For rafter legs, coniferous boards 50 × 200 mm, first-class lumber, are used. The boards must not have traces of rot or fungus, significant malformations and deep cracks. It is strictly forbidden to use low-quality lumber for the manufacture of the truss system.

To increase the protection of roof elements from decay, it is recommended to use fire protection.

Rafter blanks should be impregnated at least twice, while the material must be dry and clean. Processing is done on a flat area in dry and clear weather.

It can be impregnated with a roller, brush or air gun. It is not recommended to use household hand sprayers - too long and hard. Boards can be lifted up after complete drying of the impregnation.

Our gable roof has a ridge run, vertical supports rest against a bed located on a load-bearing wall in the middle of the building.

Practical advice. If the house is quite high and the boards are heavy, then it is recommended to make an elementary device to protect window openings from damage. To do this, two boards are knocked down in the form of a square, the length and width are selected taking into account the parameters of the opening. The device is installed on the windowsill, and the rafter boards do not damage the foam blocks during lifting.

Prices for fire-retardant impregnations

Preparatory operations

The manufacture of rafters begins with preparatory operations.

Step 1. Raise the rafter boards into the attic. For convenience, place them evenly along the length of the building, put one end on the Mauerlat, and the other on the run bed. First you need to install the extreme rafters on both sides of the roof of the house, pull the thread between them and install and align all the remaining ones along it.

Step 2 Check again the position of the ridge run. It should be located exactly in the middle of the roof. Its displacement by 1–2 centimeters will not affect the strength of the roof as a whole, but it will somewhat complicate the manufacture of rafters and the laying of roofing materials. In addition, an experienced builder may notice a mismatch in the size of the slopes and, accordingly, the asymmetry of the roof. It is recommended to achieve a situation so that the ridge run is located along the line of symmetry, if this is not associated with great difficulties. The final decision is made by the foreman on site and depends on the magnitude of the offset and the amount of work to correct the error.

How to straighten a run?

1. Attach a batten board to the Mauerlat, it is lighter, easier to lift and fix. The second end should lie on the run. The board is nailed to the Mauerlat with an ordinary smooth nail or screwed with a self-tapping screw.
2. Climb to the top of the run and check the distance from the edge of the run to the Mauerlats installed on opposite walls with a tape measure. Work very carefully, it is advisable to use insurance. Unfortunately, in practice, few people follow the safety rules, but in vain. Falls from height can cause very serious injury.
3. Align the purlin to the center and secure the board. To increase rigidity, fix the same board on the other side of the run.

Now everything is ready, you can proceed to the manufacture and installation of rafters.

Installationrafter legs

If you work alone, then you need to fasten a piece of rail to the run at the place where the first rafter is fixed. A rafter board will be temporarily fixed to it to prevent it from slipping down.

And at this time, you can perform work on the manufacture and preparation for connecting the upper part of the rafters.

Step 1. Lift and install the rafter board in place, clamp it to the previously fixed rail with a clamp.

Step 2 Draw lines to cut out the thrust pad. This is done in two stages. First, draw a horizontal line. To do this, press the rail, square or other even object firmly against the horizontal surface of the run.

Second, draw a vertical line. Now the ruler or square should be pressed against the side surface of the run.

Important. The width of the ruler should be no more than 2-3 cm, it is not necessary to make deep cuts and significantly reduce the width of the rafter leg, it loses its maximum design strength.

Make the same markup at the bottom of the rafter. Only now the ruler needs to be pressed against the Mauerlat surfaces.

Step 3 Remove the board and carefully cut out the seats. You can work with a hacksaw or an electric circular hand saw.

Practical advice. If the cuts are made with an electric circular saw, then it is better to cut in two steps. First cut to the mark, then turn the board over and cut again to the mark. Knock out the cut piece with a hammer, and remove the remaining protrusion with a chisel or chisel. No need to go behind the line with a saw and try to cut off the ledge in one go. This method increases the cut by 3–5 cm, depending on the diameter of the disk, which significantly reduces the bearing performance of the rafter.

Step 4 Install the prepared rafter in place and check the correctness of its manufacture. Do the same operations with the second leg of the farm.

Step 5 Place the rafters with an emphasis on the Mauerlat and the run, pull them together with a clamp in the upper part. Find the middle of the run and transfer the line to the rafters, use a level or building square (only if the plane of the run is strictly horizontal).

Step 6 Saw through two rafters at the same time along a vertical line. The boards must be tightly clamped with a clamp. Pay maximum attention, the saw blade should be perpendicular to the plane of the rafters. If you cut it obliquely, then the ridge joint will not fit tightly, and this reduces the stability of the truss system and is considered an obvious construction defect.

With a lack of practical experience in performing such work, the first leg may have a gap in the ridge part, if it is within 1–2 mm, then there is nothing to worry about. If it is more than 4 millimeters, then you need to correct the element. See which planes of the thrust pads do not allow the upper cut to fit tightly. Approximately indicate the amount of additional cut. Remove the rafter and remove the interfering protrusions. Check the connection again, if there are gaps, repeat the operation. As practice shows, experience appears on the second or third rafter and no further corrections need to be made.

Step 8 Secure the rafter legs firmly in place. For this, it is recommended to use metal plates and corners, it is simple and easy to work with them, the strength fully meets the requirements for the truss system.

For each pair of rafters, you will need one large reshaped plate to connect the ridge knot, two 50x50mm corners for fixing to the run and two 60x80mm corners for screwing to the Mauerlat. The thickness of the metal is at least two millimeters.

In the same way, install the extreme rafters on the other side of the house, pull the threads between them. One at the top and bottom and one in the middle. So that they do not interfere during the manufacture of rafters, make a gap between the thread and the plane of about one centimeter.

Real professionals never make one rafter in the attic of a house. Such an algorithm of work significantly increases the construction time, complicates the process itself and makes it unsafe. It is very dangerous to work with electric tools on unsuitable sites, injuries from them are severe, often causing disability.

If the house is delivered with high quality with exact observance of dimensions and rules, then the rafter legs are made according to one template on the ground. Finished elements are assembled on the roof. This technology increases labor productivity by 3-5 times, at the same time the quality of the rafter system is improved, it is more reliable and durable. Of course, the wages of builders also increase proportionally. They work from the development and receive money not for the time spent in the attic, but for the assembled roof.

Prices for popular models of screwdrivers

Screwdrivers

Video - Manufacturing and installation of rafters on a gable roof

When building a small house, garage or outbuilding, it is not necessary to hire professional builders. Most of the work can be done on your own. Even if we are talking about such a complex structure as a truss system. Even some of the materials, or rather the elements, can be made by hand. For example, rafters. This element is the main one in the roof structure. And how can you make rafters with your own hands? What are the nuances and how to avoid mistakes? This will be discussed below.

What material to choose

Making rafters for a house with your own hands is a completely doable task. But before you start it, you need to choose the right material. It is from this that the whole course of further work will envy.

And what options for the material for the rafters are used? The following can be used for this:

1. Reinforced concrete products. This option is used in the construction of large industrial facilities. It is impossible to make such rafters on your own. And their use in the construction of private houses is not practiced.
   
2. Iron. It is quite possible to make metal rafters with your own hands. But they have many disadvantages. First, the metal is afraid of corrosion. Secondly, such rafters will weigh a lot. And this makes it difficult to do the installation yourself without the involvement of technology.
   
3. Wood. It is this material that is most often used in the construction of the truss system of a private house. Wood is easy to process. Therefore, making rafters with your own hands will be quite easy.

It is wood that is used for construction. But this material also has several options. Wood can be found in the form of logs, beams and boards. And what is better to use for rafters? Much will depend on the design itself. More specifically, on the size and required strength.

Logs, due to their heaviness and bulkiness, are rarely used for rafters. Exceptions can only be a pitched roof. And then in this case, thin logs from young trees are used for rafters.


Bars and boards are a completely different matter. It is they who are used in order to make rafters for the roof. Bars are used in cases where the structure is large in size. At the same time, the loads from precipitation and the weight of the roofing material are quite large. Boards are used for rafters in cases where the roof is small in size. However, they can be used singly or in pairs.


Choice of wood

Making rafters is a responsible business. The strength of the entire roof structure will depend on it, so you need to pay attention to all the little things. Before proceeding with the manufacture of rafters, you should stock up on material. As mentioned above, wood is best suited for this.

And what breed is better to choose? What kind of wood can be used to make strong and durable rafters? You can use the following to work:

• Pine. It is this option that is most often used in the construction of a roof truss system. Pine has many benefits. Firstly, such wood is impregnated with resin. This allows you to protect it from external influences. Secondly, the material is soft, and it will be easier to make rafters out of it with your own hands. Another plus is that pine is inexpensive wood. And this means that you can save;
• Spruce is another common material for making roof rafters. This wood is strong, light and easy to work with. But spruce has a small drawback. It is more susceptible to external influences than pine;
• To make rafters, you can use oak. The material is durable and well processed. But oak is very expensive. It is best used for .

Rafters can also be made from other materials. For example, you can use beech. This wood is strong and durable, but it is expensive and difficult to process. If you have chosen aspen, then you should be aware of some of its shortcomings. Most importantly, this wood often rots from the inside.

The best option, according to most professionals, is pine. The wood is quite common, it will be easy to buy. But the most important thing is its durability and ease of processing. You can easily make rafters and other elements of the roof structure from pine.

There is another modern version. For the manufacture of rafters, you can use glued beams. This material has several advantages. First, it is not deformable. Secondly, it has standard dimensions, which greatly facilitates the fitting of rafters. But glued beams are rarely used. This material is new, and it is not cheap.

It is very important to consider the quality of the purchased wood. Of course, everyone knows that it is not worth buying bars or boards with traces of decay. But, besides this, you should pay attention to the moisture content of the wood. This parameter should not exceed 10-15 percent. Otherwise, the rafters will warp, and the roof will soon require repair.

What sizes to choose

If wood is selected, then before buying, you should deal with a few more parameters. To make the rafters correctly, you need to decide on their cross section and length. Both parameters are determined by calculations.

Having learned what load the rafters must withstand, you can calculate their cross section. There are many tables on the Internet. They indicate the bearing capabilities of the rafters, depending on the material used in the manufacture, length and section. With their help, you can easily select the desired parameter. The only thing that still needs to be taken into account in the calculations is this. The closer they are to each other, the smaller the cross section can be used.

How to make rafters on the roof? In principle, there is nothing complicated here. Having learned what the length should be, the timber or boards of the desired section are sawn off according to the desired markings. Next, a cut is made for and in the area of ​​\u200b\u200bthe ridge, and if another connection method is used, then this is not necessary. But to do everything right, you should take some advice from experts. Namely:

The semicircular roof, which has the appearance of an arch from the side of the pediment, gives the country house a certain individuality that distinguishes it from neighboring buildings with primitive gable or four-slope roofs. The main load-bearing elements in such a semicircular roof are arched rafters, the choice of which, production technology and their installation will be discussed below in the article.

What are arched rafters

A roofing ordinary rafter is a flat wooden beam with a section of 120x40 mm or 150x50 mm. When creating a rafter system for a pitched roof, all the bars are located at the same angle of inclination and are in the same plane.

An arched rafter is the same load-bearing element as a regular straight rafter, only having the shape of an arc. Unlike straight rafters, arched beams are distinguished by the material of manufacture into wooden, metal and reinforced concrete. According to the manufacturing method, arched rafters are conditionally divided into solid, prefabricated and glued, the production of which is possible only from wood.

Where and how to use arched rafters

In private suburban construction, this is the creation of truss systems for semicircular roofs of one-story and two-story cottages, as well as for the construction of a canopy for parking personal vehicles on a suburban area.

arched roof

In the field of industry and agriculture - arched rafters are used for the construction of hangars, warehouses, terminals, railway stations, and sheds in the construction of covered parking lots, bus stations, gas stations and even water parks.

With such a wide application, of course, the radius of the arc, the material and design of the arched rafters can vary significantly.

Industrial production of arched rafters

On an industrial scale, arched rafters are made mainly of metal and much less often of reinforced concrete. Metal arched rafters are called trusses and, as a rule, are transported and installed on load-bearing walls or columns in an assembled one-piece form. Depending on the expected load, metal trusses are made from such a range of rolled metal as: channel, triangle, hollow square, pipe and fittings.

Metal arched rafters
Canopy using metal arched rafters

Reinforced concrete arched trusses in most cases are made immediately at their future location, that is, reinforced monolithic trusses and crossbars are poured into a pre-prepared formwork in the form of an arch. Such construction cannot be called typical, since such architectural projects are developed quite rarely, and it comes directly to construction even less often.

Reinforced concrete arched rafters

Arched wooden rafters

For suburban private construction, arched rafters and trusses made of wood are used. According to the method of manufacture, they are divided into the following types:

• From solid wood - arch-shaped beams are made by sawing a wood sheet. Due to the large amount of waste, these arched beams are made up to 6-7 m long.
• Glued rafters - obtained by gluing a thin edged board with a thickness of 8-10 mm. The manufacturing process is similar to the production of glued beams, the only difference is that at the time of gluing and drying the future rafters are deliberately set to the selected bending radius.
• Composite arched rafters - are made both by small woodworking enterprises, and directly by the team of builders who mount the roof. Composite arched beams in their design consist of bars 100-150 cm long sewn together with metal studs.

Arched solid wood rafters
Glued arched rafters
Composite arched rafters

Making arched rafters with your own hands

The manufacture of rafters for the installation of an arched roof always begins with a calculation. There are 2 options here: "hard" and "easy" way.

A difficult way to calculate the length and bending radius of the rafters

This option provides for the development of a scheme of the following form:

Scheme for calculating arched rafters

The calculation and calculation method is as follows:

• Millimetric drawing paper is taken and it is decided on what scale the drawing will be performed;
• Next, with a tape measure, it is necessary to measure the span covered by the arched roof from one to the other bearing wall;
• Bearing walls and the distance between them are transferred to drawing paper;
• Further, the correct circle is entered between the bearing walls with a compass;
• After that, an equilateral hexagon is inscribed in the circle;
• The corners of the hexagon themselves determine the dimensions of the future arched rafters;
• This calculation is completed by transferring from graph paper to nature, that is, it is necessary to make the first arched rafter according to the drawing, which will subsequently be used as a template for the manufacture of the entire set of beams.

Easy way to calculate

There are a number of different 2d and 3d programs, as well as calculators that will help you calculate the number, length and radius of the arc of rafters for an arched roof. For example, it is only necessary to load the initial data into the calculation calculator, such as the width of the covered span between the bearing walls and the maximum height of the arch from the ceiling. The latest data is important, since it is not always the task to make a roof in the form of a half of a regular circle. Often it is necessary to calculate an arc with a smaller radius, which is more problematic manually on graph paper.

Installation of a roof from arched rafters

After completing the calculation, proceed to the assembly of the first arched rafter. For its manufacture, blanks are cut from a bar 140x40 mm, for example, 130 cm long. Next, on a flat surface, an arc is laid out from the blanks - the profile of the future rafter. After that, the same number of blanks are made, which are placed on top of the first "layer" of bars and the attachment points between them are marked. In most cases, the ends of the bars in 1 and 2 "layers" end at a certain angle. At the next stage, both "layers" of the bars are sewn together with pins.

Stud - a metal round rod with a diameter of 8-12 mm with a thread cut at both ends for a nut of the corresponding diameter. To improve fastening, lock nuts are used or a clamping gasket is placed under a regular nut. Depending on the total span and the length of the rafter, it is assembled from two or three of the above layers of bars.

Installation of arched rafters

Having prepared the first rafter, using it as a template, the rest of the set of beams is made, taking into account that there should be a step of 90-120 cm between the rafters in the roofing system. When the entire set of arched beams is prepared, they are lifted up and the roof is assembled. The lower ends of the arched rafters are attached to the Mauerlat - a massive beam, fixed along two load-bearing walls to the ceiling, with the help of studs released from it.

The connection of the upper ends of the arched rafters is made either on a ridge - a massive beam mounted on racks, or without a ridge - that is, each pair of rafters is sewn together at the highest point of the roof. If the second option is chosen, then the entire length of the roof arch is divided into equal 3 parts and, at the two points obtained, support beams extended along the entire roof are mounted, which are installed similarly to a ridge, on racks.

Roof installation

After installing the entire set of arched beams, a crate of edged boards is stuffed transversely with them. The step between the crate is selected depending on the roofing material. That is, the dimensions of the tiles. If it is planned to sheathe the roof with bituminous (flexible) tiles, then instead of the crate, the entire truss system is sheathed with OSB sheets or moisture-resistant plywood. With this design, the distance between the rafters in the system should not exceed 100 cm. Otherwise, the crate is stuffed, OSB is mounted on top of it, and bituminous tiles are already on top.

Prices for arched rafters and the cost of installing an arched roof

The price of arched rafters depends on the material from which they are planned to be made, as well as on the length and complexity of the arches. For example, when ordering arched rafters, you can find the following nonsense: the price of metal trusses can be the same as the cost of wooden arched rafters. It would seem that rolled metal is more expensive than wood, but the complexity of manufacturing arched beams plays a role here.

Sometimes ceilings become central design elements, but in addition to this, they also carry a practical load anyway.

The truss system is the supporting structure of a pitched roof. It consists of rafter legs, which are placed at an angle, as well as vertical racks. Absolutely any materials are used: wood, metal, concrete and others.

This shot illustrates well how each pair of beams connects to the horizontal bar. The load is distributed evenly, and the result is a very reliable design.

Designed by renowned Searl Lamaster Howe Architects, Chicago, IL, USA

Exposed ceiling beams are an excellent interior solution. It is this design of the ceiling in the house with a pitched roof, shown in the photograph, that makes the image more harmonious and complete. Do not forget about this simple, very affordable, but no less spectacular, design technique.

Gorgeous living room, designed by Anat Shmariahu, Cupertino, California, USA

The next shot gives us an idea of ​​how original the ceiling of the veranda can be. Here the beams are placed perpendicular to each other, and this is a very unusual architectural solution. Thus, the height of the ceiling increases, a semblance of a coffered structure is obtained.

Stunning veranda with ornate beamed ceilings, designed by the Frederick + Frederick design team, Beaufort, South Carolina, USA

The rafters protrude beyond the outer wall, forming cornices for water to drain. This is a very original solution to the problem of water drainage from the roof.

Gorgeous home design example with beamed cornices, John Lum Architecture, San Francisco, California, USA

The ends of the roof beams, which in this case are painted white, are called rafter tails. The blue rafters at the ends of the gables are outriggers.

Very unusual and stylish design of rafters, design by RW Anderson Homes, Seattle, Washington, USA

It also presents an original way of decorating a roof with protruding beams. They have no practical significance, but are simply elements of exterior decor.

Unusually cozy summer house with decorative rafters, project SRM Architecture and Interiors, Portland, Oregon, USA

Exposed ceiling beams give the room an inexpressible charm of a country house, while also performing their main function - supporting the roof. In our hectic time, country style is becoming very popular. His images set in a romantic mood, it has a calming effect. And the ceiling plays an important role here.

The textured and durable design of the ceiling beams gives a feeling of unity with nature, design by Nurit Geffen-Batim Studio, Raanana, Israel

Ornamental beams arranged in this way create the illusion of a conical ceiling. Immediately there is a feeling of flight and lightness.

Reminiscent of places of worship, this design was conceived by a design team from Aarcon Construction and Remodeling, Tombal, Texas, USA.

Rafters come in different levels, depending on the design of the house. The main thing here is to take care of the quality of the material and fasteners: the design must be stable.

Fascinatingly simple home, designed by Gaulhofer Windows, Duncan, Canada

With the help of ceiling beams, you can adjust the geometry and volume of the premises. If installed along the width of the ceiling, the room will visually expand. And to lengthen the room, the elements of the ceiling structure are laid perpendicular to each other. If the ceilings are too high, you can place the beams low under the roofing. This will immediately give the design coziness.

Ceiling beams will be appropriate in any interior, so do not be afraid to experiment! Decorative wooden rafters will bring a feeling of warmth into the room, and metal structures will create an atmosphere of an industrial loft. In any case, a room with an open ceiling structure will look unique.