What is the wood beams
The most economical option for private homes are wooden beams. They are fairly easy to install - no need to involve special equipment.
Wooden beams have the advantage compared to concrete and metal beams in terms of thermal conductivity. However, they have several disadvantages: low fire resistance, low density and, as a consequence, the ability to withstand a small load, the lack of resistance to damage caused by microorganisms and insects. Therefore, the wooden beams before the installation is processed with special preservatives.
When installing wooden beams ukladyvaetsya on the transverse support, which can serve as an additional Board, or nets, flooded along the perimeter masonry walls. The transverse support serve to evenly distribute the load on the wall, and then on the Foundation of the house. Of the beams laid on the walls, wrapped with waterproofing material, commonly used roofing material, while the ends are not isolated, which allows the beam to "breathe".
The length of the wooden ceiling beams
The required length of the wooden ceiling beams is determined by the size of the span, they will overlap, it is necessary to consider the size of the spades on the wall. The spade of the beam on the wall should be not less than 12 cm, for lumber it needs to be at least 15 cm.
If the mounting beams using special metal fasteners (clips, angles), the beam can be mounted directly in the passage between the walls, then the length of the wooden beams of the ceiling will be equal to the distance between the walls where it is attached. But in practice, most floor beam is laid on the wall.
Optimal span, over which is laid a wooden beam, 2.5 - 4.5 m. the Maximum beam length of timber does not exceed 6 m, thus defining the maximum span.
When overlapping spans of more than 6 meters are used in wood trusses.
The load acting on the wooden beams
The load exerted on the beams, the sum of the load self weight of the floor elements (beams, filler, obshivka, fasteners) and operational loads (permanent and temporary). Operating load is the vest various household items, furniture, people.
Usually, the calculation of wooden beams of the attic floor to use the value of 150 kg/m2, 50 kg/m2 is the load of its own weight, and 100 kg/m2 is the standard load for the attic (SNiP 2.01.07-85) taking into account the safety factor for strength.
If you intend to actively use the attic for storage and materials, then the overall load, primagama in the calculation is set equal to 250 kg/m2.
In the calculations of the cross section wooden beams for floors, or ceiling of the attic floor, the total load taken as equal to - 350 - 400 kg/m2.