Roof boards, which serve as a roof covering, are called rafters. It is from them that it depends on how long the roofing coverage will serve as well as the safety of life in the house. So that the rafters turned out to be high quality, it is important to choose the right material and make all the calculations.
The board for rafters is preferable edged with different cross section. Most often used option 50×150 or 50×200 mm. Do not take a rectangular or square bar, as it is too heavy and does not provide the necessary strength.
As a rule, on the roof of the rafters are installed on the edge for greater reliability. Best for the rafter systems to choose wood coniferous rocks. This is due to the fact that the resin does not give to form rot. In addition, coniferous boards are distinguished by low weight and available cost. On most sawmills, this material is presented in a wide range.
It is important that the wood is not wet. After all, when drying, the geometry of the board and the bar is changing, which ultimately spoils all the roof. It is desirable that the water content in the wood does not exceed 18%.
And it should also be paid to the fact that There should be no bitch or rotten places in the boards that can reduce strength. The wind is strongly affected by the wind, snow and roof covering, so it is worth considering many moments. For example, through cracks must be absent.
As for non-core, then only short. Plaques for the rafters are necessarily processed by antiseptic agents against rot, antipirens for protection against fire and means for scaring various pests. It is necessary that the system serve as longer as possible.
Types of material
For the rafter design, it is important to select the boards so that it turns out to be durable, but at the same time its weight was not too big. Moreover, for the roof of multi-storey buildings or industrial buildings, metallic or reinforced concrete solutions will be the optimal solution. For ordinary buildings enough wood. As a rule, in practice it is customary to use several types of materials for rafters.
The logs are very rare, more often from them make logs. This option is characterized by a lot of weight. In addition, you need a professional who knows how to work with them, in particular, with complicated livers on the places of fasteners.
- The timber timing can be used normal or glued. From it you can make a system that will be highly durable and durability. However, the cost of such a high.
- The board is rated by acceptable cost, so it is often selected for rafters. It is important that its thickness is at least 4 centimeters. Of the positive differences, it is worth noting ease, ease of installation and a good margin of safety.
Options for rafters can vary greatly. After all, this parameter is affected by numerous factors. Among them, the size of the structure, the area of the roof, the design version of the system, alleged loads from wind and other external influences. Experts recommend choosing the minimum section of 50×100 or 50×150 millimeters. When creating large spans, the size should be 150×150 millimeters, and even better 250×100 millimeters. If the dimensions of the structure are expected to be significant, then it is worth using boards with minimal dimensions of 200×50 mm, and even 200 per 200 mm.
To obtain optimal sizes, some calculations should be made. It is important to find out the load that can affect the roof. Based on this, it will be possible to determine the section, as well as other parameters of the rafter system.
There are special norms, but these data are shown without taking into account the climatic features of one or another region. Therefore, it is better to carry out calculations independently.
One of the most important parameters is the thickness of the chalkboard for rafters. After all, the strength of the future design depends on it. It is desirable that the thickness of the board makes 40-60 millimeters. And for small buildings, the indicator is deviated to 5 mm. As for residential buildings, it is better for them to prefer the chalkboard with a thickness of at least 50 millimeters.
When choosing a width of the board, you should consider the length of the span, which overlaps with rafters. The larger the length of the rafter, the greater should be the board. For example, if rafters are 6 meters long, then the boards are worth taking with a width of 150 millimeters. With the length of the legs of more than 6 meters, the width boards are selected from 180 millimeters. If the rafter foot should be very long, it is recommended to use extension.
To calculate the cross section of the rafter, it is necessary to determine the appropriate distance between them, and take into account the length of the elements. At the same time it is necessary to take into account constant load on the roof of snow and wind. The mass of the rafter system will also be involved, the angle of the slope, the length of the span of overlapping. Additionally, the width of the structure should be taken into account.
To make all the calculations correctly and quickly, you can use special programs. In this case, the obtained values will be accurate. When the cross section of the rafted is determined, you can move to finding their steps. Under this definition is the distance on which elements will be removed from each other. Such a parameter as a step is very important, as it ensures the reliability and life of the roof.
Parts of the system
The rafter system consists of farms, which are flat designs in the form of a triangle. They are set on Maurylalat, and then fasten with each other using runs. You can select some composite elements of the farm.
- The rafter feet are called the rafters themselves, which is fastened, and the roof is fastened. The farm includes two beams that are connected to a triangle on top. They must be inclined at one angle with roofing slope.
- The tightening is a crossbar that grips rafters horizontally, not allowing them to drive around under loads. Often can be seen in hanging systems.
- Rigel is a beam, which in the system is responsible for compressing, and it resembles a tightening. It is used to fasten the beams at the top.
- Battle connects horizontal beams to increase farm resistance. Applied in the utility rafters.
- The rack is used for an additional stop when fixing systems and is a horizontal beam.
- Podkova is mounted at a certain angle and is used to give better stability.
- Falcs are needed to lengthen the rafting legs if you need to make skes.
And there are elements that do not belong to farms, but are part of the rafter design.
- Run in the form of beam is installed along the skates.
- The lamp is stuffed on the rafter to mount the roof on it. Made from boards and bars.
- Maurylalat is mounted around the perimeter of walls of buildings in the form of boards or timber. The bottom ends rafters are attached to it.
- Liezharyen falls along the inner walls of the structure to fix it vertically racks.
How to choose
Boards need to choose only from proven sellers who can provide all the information you may. It is important that accompanying documents are attached to the material with a specific information:
- a variety of wood from which the boards are made;
- standard number;
- the company manufactured by the material;
- timber parameters;
- Wood moisture.
According to the tree of wood for rafter systems, preference is worth sending conifer. The optimal option is larch, but it is worth considering her rather big value. Pine, cedar or spruce is suitable as a replacement.
Do not choose deciduous rocks, since their wood is not so elastic. Exception is only oak, but because of its high cost it is impractical to take it for rafters.
It is best to give preference to the forest, which is harvested in winter. The quality of such wood is higher than prepared in the spring and summer months. For rafter feet, a timber with a thickness of 5 centimeters is suitable. As for the width, it depends directly from the construction of the rafter and load on them. Most often it is 10-25 cm. In this case, the length will be standard – 6 meters. If necessary, it can be increasing.
For runs, it is better to use a bar with a thickness of 10 centimeters. For Mauerlat, a board 15×15 centimeters is suitable. It is worth noting that this item can be collected from several boards so that it turns out even stronger. For auxiliary parts like racks, trenches, tightenings, koblok can be chosen 5×10 centimeters. You can take a timber for rafters, but then the cost of such elements will increase. The crate can be made from the board with a cross section of 2.5×10 cm.
Buy boards can be cubic meters, to order and in the form of a finished design. Each option is distinguished by its features.
- Forest cubic meters suitable if you want to save. In the large volume there will be a different material, so it is worth taking a minimum of 10%. It is important to mount the boards, if necessary, remove the Cour, to handle the antiseptic. Only smooth materials should be selected so that they are not led.
- Planed boards to order will cost a third more expensive, but accurately match the desired size. At the same time there will be little waste. However, it is necessary to ensure that the wood is not pickled, and on the canvases there were no defects.
- Finished collapsible structures attract accuracy of measurements and ease of installation. Before their manufacturement of the company, the measurer is sent to all the features of the project and wishes. As a result, the buyer will receive a competent and high-quality, but expensive system.