Is an air gap needed inside a Thermomur basement?

[plan-g]

Applies to a future basement.

One builder says you can just attach OSB+drywall directly to the inside of the thermomur basement.

Another says a ventilating air gap is needed inside the OSB.

😱

 

[joakim_j]

I will attach OSB+gypsum directly to the blocks in my basement anyway. There is nothing in the installation instructions about an air gap.

 

[plan-g]

I'm going to put OSB+plasterboard directly on the blocks in my basement anyway. There is nothing in the installation instructions about any air gap.

Ok. Hmm wonder why the builder got that idea then. I've understood it the same way as you.

Well, an air gap can't do any harm anyway...?

 

[jalmars]

OSB and plasterboard on a basement wall? Exterior wall? Is the builder suggesting an air gap because there is a risk of penetrating moisture through the wall? In that case, I would choose plaster instead.

 

[Argastesnickaren]

I set up a 45a as an installation layer where all the electricity could be run, easier than cutting into the styrofoam.
Then I insulated it before osb, gypsum was put up.

 

[joakim_j]

OSB and drywall on a basement wall? Exterior wall? Is the builder suggesting an air gap because there is a risk of penetrating moisture through the wall? Then I would have chosen plaster instead.

Do you know how a thermomur wall is constructed? It would take a lot for any penetrating moisture to occur.

 

[Plupp 405730]

Regarding a future basement.

One builder says that you can just put OSB+gypsum directly on the inside of the thermomur basement.

The other says that a ventilating air gap is needed inside the OSB.

😱

Yes, the smartest thing is to have an installation rule on the inside. 28x70 is the smallest I recommend, but if you have room for 45x45, that's good.

 

[joakim_j]

Note that the assembly instructions (at least one of them) prescribe fire boxes, which I believe basically everyone ignores...

 

[jalmars]

Do you know how a thermomur wall is constructed? It takes a lot to get any penetrating moisture.

Yes, I understand that it should be relatively airtight, and provided that there is a functioning drainage system and a correctly installed sealing membrane on the outside, it takes a lot, as you say. But then the ventilated air gap doesn't really serve a function. However, an installation layer is, of course, nice.