Good afternoon, dear guests and subscribers of the "Build for myself" channel!
In one of my articles on wood flooring, several readers have asked the same question about preparation of the ends of wooden beams before direct installation in the unit supporting them on a brick wall. Therefore, this article will answer the question posed and take this opportunity to thank people for their interest in my channel and for their positive comments on the materials.
There is a lot of information on the network that the end of the beam needs to be cut at an angle, namely by a third of the height of the product:
But what is the purpose? Many argue that this is done to provide sufficient ventilation in the pocket of the beam support unit against the wall. The second option is that by increasing the cross section of the end of the beam, its properties are improved in terms of removing excess moisture from the structure.
When constructing the roof of my house, I had a conversation with a carpenter who has been working in this field for 40 years. And, indeed, as the builder explained, the support nodes of the beams are potentially dangerous places where all conditions for the formation of condensation, since there is a high probability of freezing of the facing part of the building and blowing facade. But, washed down the butt has nothing to do with this.
To ensure ventilation - on the sides, from the end and from the top, the beam is not pinched in the wall, it rests only with its lower part on the supporting wall through two layers of roofing material on cardboard base!!! A gap of ~ 10-20 mm is left on the sides. This measure ensures sufficient ventilation in the bearing unit.
As for the end, this is an exclusively constructive element and it is performed so that during deflection the beam does not cling to the bearing wall with its edge:
But why is the cut created precisely by means of a piece, and not a saw cut?
As already noted above, the pocket where the beam is located will always be in unfavorable conditions, just in the zone of condensation formation. And, torn wood fibers at the cut with a hacksaw will contribute to moisture accumulation and water retention precisely at the end, which is prohibited.
When cutting with an ax, the fibers are compacted and the degree of wood sorption in such places becomes minimal.
If you want to simplify this procedure, you can cut the butt and then, without fail, cut the entire plane with an ax.
Rather, you noticed when freshly sawn boards are brought in, sawdust lumps on them after the sawmill. When cleaning the boards, just under the sawdust stains of blue and fungus are formed - because fluffy and loose wood fibers have high degree of sorption .
When cutting with a saw, the effect is the same. From the side of the torn wood fibers - the beam always rots many times faster, in contrast to the hewn end.
Author's advice
Try not to coat the support part with bitumen, since it has practically no steam permeability. It will be enough to soak it with oil, drying oil or a modern antiseptic, then wrap it in two layers of roofing material and install it!
Thanks for attention! Good luck with your construction!
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