Oak purlins

Most roofs of family houses have traditional wooden trusses. However, more and more investors are choosing prefabricated buildings. In both options, the basic building material is wood, which has proven itself in these applications for centuries. Very popular for their properties are oak purlins. It is located in the ridge or at its foot (wall plate).

Accurately and economically 

The design of the roof beam is based on specific assumptions – the functional arrangement of the attic, the planned type of roofing and the possibility of supporting the structure on the brick part of the building or other elements, such as reinforced concrete.

If the attic is to be fully usable, then the traditional truss construction is most often used and oak purlins are used. If it will not be used or only rarely, it is worth considering the use of a prefabricated rafter. In this case, the construction is usually carried out by the manufacturer of the prefabricated wooden trusses. However, this cannot be done for every building.

Traditional oak purlins

The traditional roof beam is made of wooden elements (logs, beams, chips, slats and planks) that are twisted or broken on the construction site. Generally, this material is purchased in structural wood warehouses and sawmills. Soft wood (spruce or pine) is most often used for construction.

Wood classes are marked by symbols, for example: C18, D20, C22, D24, C30 etc. 

• letter – the wood type, C-coniferous, D-deciduous 
• number – it characterizes the bending strength 

In addition to the properties associated with the strength of wood, an important parameter is also its moisture, which is associated with deformability during drying, i.e. shrinkage – due to drying and swelling – with increasing humidity. Due to changes in humidity, the strength of this raw material also changes. Wet material has low strength and elasticity.

The building material must therefore be properly dried. Softwood can have 13-23% humidity, depending on the relative humidity. Elements with humidity above 24% are not suitable for roof applications. Dry wood that is not dry enough can be dried by placing it under the roof so that air can circulate. Improperly arranged wood will not have sufficient ventilation and may also deform as it dries. Oak purlins must be able to withstand weather conditions, humidity and be really strong. Poorly stored wood will cause many worries in the future.