For over 50 years we have been dealing, with love and passion, in the construction of wooden buildings and we care about everything we fabricate, for this reason we have created a small guide, given by our experience in the field and by the authoritative advice of the TBZ studio located in Bozen, on the best realization of one of the most critical constructive knots when it comes to wooden buildings: the attachment to the ground of the wooden walls.
The key principle to always keep in mind is the following: the worst enemy of wood is water, so every possible action must be taken to keep them at a distance.
This follows that the wood must not be in contact with the ground because it is rich in water (including rainwater). But what does it translate into? The wooden wall must be raised from the foundations and this can be done through a curb that can be ventilated or in reinforced concrete.
Below you can see an example of ground connection with the appropriate insulation.
But let’s explain: Starting from the skeleton, as you can see, the wall, which in this case is a frame system (therefore composed of crosspieces and uprights in glulam laminated wood with an internal insulation layer closed by OSB panels on each side) , rests on a curb in reinforced concrete built on top of the foundations. It can be more or less high depending on the internal systems (closure of water / electrical systems on the floor in lightened concrete + screed) and the potential ventilated metal curb. It is always covered with a bituminous sheath to avoid rising damp.
On the internal side, attached to the load-bearing wooden wall, we find a plasterboard / fiber-gypsum structure prepared for the passage of the wall systems and the additional layer of insulation, which starts from the internal foundation floor. Adjacent to it (directly above the foundations) a layer of insulation is laid on which the finished floor is then installed.
On the external side, on the other hand, attached to the wooden load-bearing wall, starting from the lowest point of the foundations, we find a bituminous sheath that goes up along the wooden wall up to about 50 cm; above it, always starting from the ground up to about 50 cm from the ground, we find a layer of external insulation made of XPS (ideal material against humidity); continuing along the wall we will always find a layer of external insulation which can be of various kinds. Continuing with the stratigraphy, mesh, plaster and finish will be applied to the upper part, while for the lower part (meaning below the level of the sidewalk) an area (20 cm wide and 20 cm deep) will be prepared with draining scree.
This is our solution for this constructive node which, as you have seen, requires meticulous attention to every detail and the implementation of all possible actions to keep the water element at a distance.