Do I need to leave gaps between OSB sheets during installation?

Good afternoon! There is a question on the text below, which is posted on your site, related to the fastening of OSB to the concrete floor (screed):
“A rubber-based parquet adhesive is applied to the underside of the OSB, using a notched trowel for uniform application. Glue the sheets to the concrete base.
Additionally, OSB is fixed with driven dowels. For guaranteed retention, the dowels are hammered around the perimeter every 20-30 cm. If the floor is level, the installation is carried out in a dry living room, then it is enough to fix the dowels in the corners of each plate (subject to the mandatory use of high-quality glue!).
When laying between the plates, expansion joints of 3 mm thickness are left. Along the perimeter of the room, between the OSB and the wall, the seam should be 12 mm. "These gaps are necessary to compensate for the temperature and humidity expansions (blisters) of the OSB during operation."
Question: Tell me please, if the OSB is glued to the floor, and even additionally fixed with dowels, how can it expand at the same time? Does it make sense in expansion joints. Or, as I understand it, the bottom layer of the OSB will adhere firmly to the floor, and can the inside and outside layers of the OSB be subject to expansion?
And another question: if the laminate is laid on OSB, is it necessary to glue OSB to the concrete floor?

Evgeny Anatolevich

Expert Answer

Believe me, thermal expansion is such a thing that no dowels and glue can hold. I had to see, for example, how cracks formed in the bearing walls with a thickness of one and a half bricks due to an improperly equipped warm floor! And all this is only due to the fact that the thermal gap was not provided and the damping tape was not laid.

In this case, the need for expansion joints is caused not so much by thermal deformations (they are not so significant in wood), but by swelling of the wood due to the humid environment. But here linear thermal changes can reach significant values. If you do not provide gaps between the OSB sheets, then this will cause them to warp and swell, which, accordingly, will let the whole work go down. The same applies to the technology by which the rough floor is glued to the concrete screed with parquet glue. All these nuances allow you to eliminate any deformation and make the coating as durable as possible.

Similar entries:

What is the gap between floor boards?

Do I need to drill ventilation holes in mineral wool under the subfloor

What can not be left in the same housing when moving