Floor plan facade section rafter roof. Rafter plan: we facilitate the calculation of the system. Subtleties of long-span hanging systems

The rafter system can be made not only in the form of a triangle, but also in the form of other structures. But no matter what material and what form will be used, first of all, you still need to know what a rafter plan is.

What you need to know to develop a rafter plan

In order to save living space, choose attic truss systems, since it is with their help that it becomes possible to equip an additional living room in the attic.

In general, such a process as designing a rafter system can be classified as quite complex, since it requires certain skills, knowledge and skills. Therefore, to carry out all the necessary calculations and competently draw up a drawing, it is best to use the services of a specialist who already has some experience in such work.

The most important parameters that must be taken into account without fail, starting from the design stage of the roof, can be called:

• The angle of inclination of roof slopes
• Choice of section of rafters
• roof type
• Material to be used for roofing
• Calculation of the rafter system

The level of inclination of the slopes must be taken into account when selecting material and when calculating the strength of the supporting structure, which is necessary for any roofing work.

Most of the materials that can be used for such purposes can have a very tangible impact on the design of the rafter system as a whole. Therefore, it is necessary to choose the material that will be used to cover the roof very carefully, with all responsibility, and this must be done even during the design.

The drawing of the truss system must be calculated with special care, since all the possible errors and shortcomings that are allowed when assessing loads may well lead not only to damage and deformation of the rafters, but also to the complete destruction of the roof already during its operation, up to the complete collapse of the roof.

Development of a rafter plan

The process of developing a rafter plan includes procedures such as:

• Construction of modular axes tied to the thickness of the bearing walls of the building. In this case, on the plan itself, the removal of the crowning cornice is shown on the outer wall using a contour line.
• Also, ventilation and pipelines should be indicated on the plan, their location must certainly be taken into account when arranging the elements in the design of the truss system.
• Based on the selected roof structure, a plan is being developed. At the same time, the walls and the fastening of the rafters in the ridge must be taken into account directly on the sketch.

Using such a sketch allows you to draw a plan of the rafter system, with Mauerlats, longitudinal struts and posts, a rafter beam, and rafter legs indicated on it.

The selection of a suitable distance between adjacent rafters is carried out based on:

• from the weight of the material that is chosen to cover the roof,
• scaffolding that will be used in this case,
• the pitch of the rafters can be changed due to the need to pass ventilation pipes or a chimney through them.

Also, ventilation and a pipe can be skipped by interrupting the legs of the rafters, for which their ends are supported by special wooden jumpers that are located between the adjacent rafters and fixed using a special rafter saw.

If we are talking about gable roofs, then the dormers should be on the gables, which, in turn, are located at the ends, which cannot but increase the efficiency of attic ventilation in summer.

The features of the roof project with four slopes imply the display on the plan of the arches, leaning on diagonal rafter legs, as well as the dormer windows located on the hips.

In cases where the space under the roof is planned to be used for the construction of the attic floor, this should also be displayed in the figure in the form of upper beams that will serve as support for the rafters.

Also, one should not forget that the layout of the rafters should be developed simultaneously with the plan for the various designs of the sections of the building. And both of these plans must necessarily be united by the presence of a common connection.

The drawing should take into account the data of all distances between the modular axes of the proposed structure, since it is with them that all indicators of the thickness of future walls are associated.

Directly in the plan itself, the distances between the chimney, ventilation and racks must be indicated.

In addition, callouts should be displayed on the plan indicating all the necessary values ​​\u200b\u200bof the cross sections and lengths of all available parts.

When designing a house, attention should be paid to the truss system. A so-called rafter plan is necessarily drawn up, which includes all the features of the structure, the pitch of the rafter legs and other points necessary to build a reliable and durable roof that can withstand the calculated loads.

Rafter system design

Drawing up a rafter plan for a hipped roof, a gable roof or for another structure is a complex and responsible process at the same time. That is why a special program is used to draw up the drawing, it is required to take into account the calculations of snow and wind loads, the weight of the roofing material, and the dimensions of the house itself. The plan is drawn up by a specialist who has the necessary experience in performing such work. When drawing up a rafter plan, parameters such as:

• material for the construction of the roof (it can be wood or metal);
• type of roof, its features;
• roof pitch;
• section of rafter legs;
• if the listed data are available, you can proceed to the implementation of the plan of the truss system.

The design scheme of the rafter legs depends on:

• shape of the future roof;
• the length of the floors and the space to be covered;
• the presence of internal supports.

The plan of the rafters should be drawn up taking into account all the parameters. For the construction of the roof, layered and are used. The leg structure can be triangulated to provide maximum rigidity and strength. If the farms will be used complex, then you will additionally have to purchase:

• struts;
• crossbars;
• puffs;
• additional racks;
• truss beams.

Laminated rafters are used for houses where the middle one is taken as a load-bearing wall. includes 2 rafter legs, a power plate on which they rest from below, and a ridge run for support from above, as well as racks. Racks are mounted on a bed, it is placed on an internal load-bearing wall, which makes it possible to correctly distribute all the loads. If there are no internal walls, then the support falls on pillars or columns, the step between which is 6.5 m.

Hanging rafters are used when internal supports or walls are completely missing. In this case, the rafter legs will only rest on the outer walls.

The structure includes the rafter legs themselves, a horizontal beam in the form of a stretch. The lower ends of the bars rest on a special Mauerlat over the wall, which allows you to distribute the load evenly. Such rafters can provide an overlap of space of 7-12 m. Crossbars are used for reinforcement.

The production of hanging rafters is more complex than layered ones, which is why the latter are used much more often. The cost of hanging rafters is higher, but in some cases only they can be used. Combined systems can be used to reduce costs. This makes it possible to make construction easier and more economical.

What does a truss system plan include?

The drawing is made using a special program. When drawing up a drawing, the following actions are performed:

1. Modular coordination networks are applied first, they allow you to link all the data on the design of the truss system to the main walls of the future house.
2. The plan draws all the channels of the ventilation and smoke systems, pipelines, which during the construction process will go through the truss system.
3. A plan is being developed for the future chosen form of the roof. When drawing up a sketch, it is required to take into account the location of the walls.

The diagram must indicate such elements that the roof has: roof ribs, valleys, skates, and so on. Be sure to take into account what shape the slopes will take, the direction and angle of the slope. The drawing indicates the location of gables, dormer windows, if any.

Using the plan of the roofing system, the builders will build a solid and reliable structure. The following parameters must be indicated on the plan:

• rafter beams;
• Mauerlat;
• rafter legs;
• puffs and filly for fastening legs;
• racks with longitudinal struts, guaranteeing the spatial rigidity of the entire truss system (in the drawing, such elements must be displayed as a dashed line).

If it is planned to build a metal roof truss system, i.e. special galvanized beams, it is necessary to use completely different programs designed for design. Only a specialist can do this, otherwise, if the calculations are incorrect, the roof will not withstand the loads. The step of the rafter legs is calculated taking into account the building material, the loads from the insulation. For example, for a four-slope roof, which is constructed from wood, the rafter pitch can be:

1. In the manufacture of rafter legs from beams, the step is 150-180 cm.
2. In the manufacture of rafter legs from edged boards, the step is 100-120 cm.

It is important that the ventilation outlets of the pipes are displayed on the plan, as structural reinforcement may be required.

In some, in order to pass the pipe, it is necessary to cut the rafter leg, and install the remaining ends on special wooden jumpers, which will be located between the adjacent legs. For fasteners in this case, washed down. Scheme of the truss system.

Technology rules

For a hipped roof or other configuration, small dormer windows are provided in the gables to ensure proper ventilation of the attic, especially in the warm season. For example, for a four-pitched roof, it is necessary to display diagonal slanted rafter legs on the rafter plan, and the sprigs resting on them. It is important not to forget about the dormers, which will be located on the hips.

If it is planned to build an attic living space, then the upper beams for tying the walls should be displayed on the plan. They will serve as a support for the rafter legs of the entire structure, providing the necessary strength and reliability of the roof. The design scheme is always carried out simultaneously with the development of plans for all structural sections of the building. This allows you to connect them together, to ensure correct and clear design. As a result, each node will be clearly connected with the rest, the design will be stable and reliable.

The project must have the affixed values ​​​​of the axes of all elements of the building and the structure of the truss system. Wall thickness data is attached to the axial parameters, dimension lines are applied to the project, which are performed to determine the step for the beam. Inside, the distances between individual racks, chimneys are indicated. Be sure to enter the value of the cross sections for each element.

Drawing up a plan for a hipped roof or any other is a prerequisite during the design of a house. The rafter system is one of the most important elements of the house. It depends on how correctly the drawing is drawn up and the calculations are carried out, whether the structure will be strong and reliable. Therefore, it is best to entrust the preparation of such a plan to specialists, and not rely on one's own strength in the absence of proper experience.

During the construction of cottages and country houses, rafter systems used in residential buildings are used. This article will talk about how a rafter system is designed, what a rafter plan is and how it is drawn up to facilitate the calculation of the system.

Rafters for residential buildings are most often made of wood. Such truss systems are usually made in the form of a triangle, although other designs are sometimes used.

If it is necessary to save living space, attic truss systems are used, which make it possible to equip another living room in the attic.

Design of roof systems and rafters

Designing a rafter system is a rather complex task that requires special skills and knowledge. To do this, it is necessary to correctly calculate the snow and wind, the optimal weight of the system.

Therefore, the greatest efficiency and durability of the built house can be achieved if the calculation and drawing of the truss system is performed by a competent, qualified specialist with experience in performing such work.

The most important points to consider when designing a roof are:

• Type of roof being built;
• slope angles;
• The material used to cover the roof;
• choice of section of rafters;
• Calculation of the structures of the rafter system.

At the same time, the slope of the slopes also affects the calculation of the strength of the supporting structure and the choice of material that will cover the roof.

Most of these materials directly affect the design of the truss system, therefore, the coating material must be selected at the design stage.

The truss structure should be carefully calculated when designing the roof, since the shortcomings made in the assessment of loads can cause both deformation of the rafter structure and violation of the roof covering during operation, and collapse of the entire roof.

The load-bearing structures of the roof, consisting in the case of a pitched roof of battens and rafters, ensure its stability and strength.

The structural layout of the rafters depends on the following parameters:

• roof shape;
• The presence of internal supports and their location;
• The length of the overlapped space.

When drawing rafters, it should be borne in mind that rafters or trusses of rafters are hanging and layered (the most common type).

Most often, the design of the rafters is made in the form of a triangle, which provides maximum rigidity and efficiency.

Complex rafter trusses include a number of different additional elements, such as:

• Rafter beams, also called rafter legs;
• puffs;
• Crossbars;
• Racks;
• Struts, etc.

Let's take a closer look at the two main types of rafters:

1. Laminated rafters are installed in houses where the middle wall is the load-bearing wall. They include two rafter legs, the lower ends of which rest on the Mauerlats - the bearing bars, and the upper ones - on the ridge run, which is supported by racks. Racks are installed on a bed, located on a bearing internal wall. Mauerlat and lying serve to distribute the load on the walls. In the absence of longitudinal internal walls, the rafters should be supported on transverse internal walls or on pillars, the distance between which does not exceed 6.5 meters. With one additional support, the width of the covered room can be increased up to 12 meters, and with two supports - up to 15 or 16 meters. The increase in span complicates the design, since it becomes necessary to introduce additional ones, such as racks and struts, to increase the stability and lateral rigidity of the rafter system, turning the rafter structure into a truss.
2. are used in the absence of internal supports and rely only on external walls. The composition of the hanging rafters includes inclined rafter legs and an extension, which is a horizontal bar that receives the thrust from the legs of the rafters. With the lower ends of the rafter legs, with the help of a puff, they rest on the Mauerlats, and for the upper ends, the rafters are fastened in the ridge. The simplest version of the hanging rafters is a triangular symmetrical truss, and the volume of the overlapped space can be from 7 to 12 meters. You can strengthen the structure with a special screed - crossbar.

Important: it should be noted that the manufacture of hanging rafters is a rather laborious process, and their cost significantly exceeds the cost of layered ones. Therefore, quite often, in order to reduce the cost of construction, combined systems of rafters are equipped, which include both hanging and inclined rafters.

Development of a rafter plan

When developing a rafter plan, the following procedures are performed:

• Application of modular coordination axes, to which the values ​​of the thickness of the main walls of the building are attached. In this case, the extension of the crowning cornice of the structure used is displayed on the plan of the outer walls in the form of a contour line;
• On the plan, smoke and ventilation ducts and pipelines are drawn, the location of which is necessarily taken into account in the process of placing elements of the designed rafter system;
• They develop a plan for the selected roof shape in the form of a sketch, which should also take into account the location of the walls. A ridge, valleys, ribs, as well as the following elements are applied to the plan in the form of lines:

1. The shape of the roof slopes;
2. The direction of the slope of the slopes;
3. The location of the dormer windows;
4. Location of gables, etc.

• Using the roof plan, a rafter system plan is drawn, on which the placement of the following elements should be indicated:

1. Rafter beam;
2. Mauerlats;
3. Rafter legs with fillies and puffs, based on Mauerlats;
4. Racks, as well as longitudinal struts, providing the necessary spatial rigidity of the truss system (displayed as a dashed line);

The cross-sections of various elements take indicative values ​​depending on what type of wood will be used in construction (boards, beams or logs). The step of the rafters, that is, the distance between them, is selected depending on what kind of scaffolding is used in the construction of the roof, as well as on the weight of the material used to cover:

• The step is 100-120 cm;
• The pitch of the rafters made of beams is from 150 to 180 cm.

In addition, the distance between the rafters can change when passing chimney or ventilation pipes between them.

In addition, these pipes can be skipped by interrupting the rafter legs; for this, their free ends rest on lintels made of wood located between adjacent rafters, for the fastening of which a special rafter is washed down.

In the case of gable or gable roofs, dormer windows are placed in gables located at the ends. This increases the efficiency of attic ventilation in the warm season.

When developing a four-pitched roof project, elements such as oblique diagonal legs of rafters, sprigs resting on them, as well as dormer windows located on the hips, should be displayed on the plan.

In the event that an attic floor is equipped in the under-roof space, the plan should also display the upper beams of the framing of the frame walls, on which the rafters will rest.

It should also be borne in mind that the development of a plan for the rafter system should be carried out in parallel with the development of a plan for various structural sections of the designed building, which should be interconnected.

• On the drawing of the truss plan, the values ​​​​of the distances between the modular axes of the designed building are put down, to which the values ​​\u200b\u200bof the thickness of the walls are attached. Dimension lines, on which a chain of steps between the rafter axes is marked, are drawn on the plan closer to its contour. Inside the plan, the distances between the racks, ventilation and chimney pipes, as well as between various structural elements of the truss system are indicated. In addition, callouts must be displayed on the plan, on which the values ​​​​of the lengths and cross sections of the listed elements will be indicated.

The truss system is the most important element of the construction of the roof being erected, on the correct design of which such indicators as the reliability of the roof, its safety and the duration of the service life depend.

Therefore, without having the required skills and abilities, it is better not to take on the preparation of a rafter plan, but to entrust this work to a qualified specialist with the necessary experience.