Calculation of the rafters with his hands

Rafter system - "skeleton" of any roof structure.From the correctness of its manufacture and installation depends directly on the reliability, quality and durability of the roof.If desired, with the arrangement of roof system can be managed independently.Want to know how?Examine the following guidelines!

Species roof systems

There naslonnye and hanging truss system.According to statistics, the most commonly used design naslonnogo type.When constructing such a system rafters abut mauerlat.The function performs a simple central ridge pole.To increase the strength of the beam support system installed.

In the case of hanging rafters system design is completed by additional struts, contributing to the optimal distribution of the load over the entire area of ​​the roof structure.

Production and installation of trusses of both species carried out in the same sequence, but with the features and the differences listed above.

Video - Rafter system

design of roof system

Any truss system consists of the following major components:

• rafters.Are mounted parallel to the slopes.Prevent sagging roof structure;
• run.Is a cross-beams, mounted lengthwise on top;
• sills and pillars - supporting truss construction girders;
• braces - components podstropilnoy farms that give additional stability rafters.
  

  scheme rafters

What do rafters?

The most common rafters are made of softwood.It is relatively inexpensive, fairly durable and easy to process material

In the case of independent production rafters best to use bar section 10x10 or 15x15 cm.

Also, when choosing a timber you need to pay attention to its moisture content.The maximum allowable rate - 20%.At higher values ​​of the material will shrink, causing disruption of the entire roofing system configuration.

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Preliminary calculations

calculates the optimal length of the rafters.The standard length of products factory production of 450 or 600 cm. If necessary, you can change the length of the rafters.

To determine the optimum cross-section beams need to know the following:

• length of the rafters;
• step mounting elements;
• estimates of future loads.

required information is given in the following table.

Table 1. Selection step installation rafters, depending on their length and cross section

length rafters, m	distance between the rafters, see	section size timber trusses, see
Up 3	120	8x10
Up to 3	180	9h10
Up to 4	100	8x16
Up to 4	140	8h18
Up to 4	180	9x18
Up to 6	100	8h20
Up to 6	140	10x20

remaining elements of the roof system should have the section:

• mauerlat - 10x10 or 15x15see also allowed the installation of mauerlat bar section 10x15 cm.;
• diagonal rafters and valley - 10x20 cm;
• tightening - 5x15 cm;
• runs - 10x10, 10x20 cm;
• struts - 10x10 or 15x15 cm;
• Hem board - 2,5h10 cm;
• crossbars - 10x15 or 10x20 cm
  

  Load Calculation of the rafters

Knowing the length and cross section of the rafters, and the step of installation, you can easily calculate the required number of items, focusing on the structure of the length of the wall..

addition should be made to the calculation of the rafters sag.That is, you need to learn how rafters can bend until they break.For example, when designing a mansard roof truss design calculation should be done so that the deflection was not more than 1/250 of the length of the section, which is under pressure.

truss system Based on the above, if the line length is 500 cm, the maximum deflection value will be 0.2 cm. The indicator seems insignificant, but in case of exceeding the deflection of the roof will be visually noticeable, and on reliabilitydesign it will affect not the best way.

Video - calculation of the rafters with his hands

Transform wooden beam in the rafters

Produce template by which will be carried out further work.Rafters have the same design, so that the template will save you time and energy.

template connects two boards on one edge of the nail.As a result, you should get a design that resembles a pair of scissors.

Put the free edge of the "scissors" to support the points of the future placement of the rafters.This will determine the slope of the roof slope.

Take an extra pair of nails and fix the angle set between the boards.This template is ready.Additionally fix it crossbeam.To set the angle of slope of the roof slope has not changed under the influence of loads, attach with screws bar.

Be extremely careful when creating the template.Even for the slightest deviation can spoil the whole structure.

Then make a new template for the preparation of installation gouge on the elements of the system.Use plywood thickness of 0.5 cm. To strengthen the use of 2.5-centimeter board.Dimensions gouge selected taking into account cross-section used in the rafters.

With the help of ready-made templates make gouge and begin to collect the farm.

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How to assemble the farm

design includes support legs and connecting components.Farm resembles a triangle.Perform work in the specified sequence, and finished construction can adequately carry all loads coming.

Farm can be done on the ground with a further rise of the top or else directly on the roof.The first option is more convenient and simple in execution.

roof trusses assembled in the following order.First, cut the harvested material to a desired size, butted bars upper edges and are fastened with screws.To prevent cracks in the bonding pre-drilled holes in the bars with a diameter slightly smaller than the fasteners.

also to connect rafters use the deadbolt.Fixing is done on two feet below the top of the binding elements.Crossbars will enhance the rigidity of the structure and will eliminate the risk of depression.Mounting bolts perform in recesses previously furnished to the rafters by punching.

If necessary, rafters are cut at an angle, especially if it is required to equip the roof structure.

Installing truss

Installation of roof trusses is performed in the following sequence:

• assemble extreme farm;
• fix the central farm.

Installation extreme farms adhere to the following important rules:

• base triangle set on mauerlat or the upper frame in the case of arrangement of the wooden structure of the roof;
• previously done at the base of a few holes for subsequent bonding with log cabins;
• necessarily control the straightness of the installation of the farm.To do this, we use a plumb line, attached to the girder;
• base truss anchoring only after the flatness of its installation;
• to provide additional farm sustainability anchoring jib from log to the rafters.The length is selected according to the situation of fundamental importance, it does not have;
• before tightening the jib screws again we see the straightness of its placement.
  

  Rafter system

  

  Manufacture lower belts trusses

  

  assembly truss

  

  assembly truss

  

  Trussed rafters are installed in the design position

Aftercomplete the installation of extreme farms turn to the central fixation and subsequent designs, if their accommodation provided by the project.Optimal farm installation step -. 100 cm

to secure the central rafter of a triangle using temporary jib.After you have installed the visor, jib can be removed.Recommendations for attachment and the rest of the central truss are the same as in the case of extreme designs.

After all the design elements are starting to mount crates and further arrangement of the roofing system: moisture, heat and paroizolirovaniyu, as well as installation of the selected finish.

Successful work!

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