Do I need to drill ventilation holes in mineral wool under the subfloor
The rough floor is made of OSB, the insulation is mineral wool, do I need to drill holes for its ventilation?
Sasha
Expert Answer
Hello, Sasha.
If the subfloor is equipped using OSB or plywood, then additional holes in sheet materials are not required. With ventilation, the gaps between the individual panels and the compensation gaps that leave along the perimeter of all the walls inside the house do an excellent job.
Since you plan to use mineral wool, it is much more important to correctly solve the problem of vapor barrier - high humidity significantly reduces the operational characteristics of this rolled material. In addition, above the “pie” from the heater and vapor barrier membrane, a ventilation gap must be provided - a space 20-30 mm high. This opening is needed so that air currents can freely move under the plates, and moisture quietly evaporates from the surface of the protective film. Visually, the method of arranging a rough floor from OSB-plates and mineral wool can be seen in the figure below.
The heat-insulating “pie” itself is laid according to the following scheme:
- A vapor barrier film (for example, the same Isospan B) is laid on the supporting frame of the subfloor. At the same time, it is important that adjacent canvases overlap by at least 10-15 cm. It is best to fix the vapor barrier with a special adhesive tape.
- The protective membrane must be oriented with the passing side towards the mineral wool.
- The space between the lags is filled with insulation. As mentioned above, the height of the insulating layer should be 2-3 cm below the upper cut of the log.
- On top of the mineral wool, another layer of vapor barrier is laid. The work is performed similarly to claim 1.
- Mount OSB boards. Be sure to make sure that the joints are in the middle of the rails and not allow the connection of all four corners in one place.
You did not provide information about the type of foundation, so in conclusion I would like to note the importance of arranging special ventilation ducts if the floor is not built on a columnar or pile foundation, but on a shallow tape foundation. The so-called vents are made in the form of channels with a diameter of up to 100 mm, which are obtained in the body of a concrete strip when pouring mortar or after setting, using a diamond crown and drill or perforator.
