Subfloor, Asfa board under the studs?

[bjoesk]

Hello.

I am planning to expand my vacation home, which is standing on pillars. The existing deck will be demolished and used for the extension. Subfloor boards seem to be asfaboard in narrow, expensive pieces. Is it possible to attach asfaboard 1200*2740 screws underneath the joists instead of fiddling with the small pieces in between?

The difference seems to be that the asfaboard is 12 mm instead of 6 mm. The price is double for the smaller narrower pieces.

What do you think?

Best regards, Björn

 

[Per i Hamrånge]

I would screw a plank under the floor joist lengthwise. It should be wide enough to hang out about 2cm on the sides of the floor joist. Skip trying to screw a strip on the side of the floor joist. Just cumbersome. And it also provides more space for insulation. Then you put in subfloor panels of oiled board or cement-based ones. Avoid asfaboard. It is considered to promote mold growth. Subfloor panels are quite expensive, but if you have the right cc between the floor joists, you've done the job in half an hour. Just lay them in and start insulating.

 

[bjoesk]

Thank you, Per.
So just keep your fingers crossed that the cc distances are okay.
Are these the ones you mean? -->
Unfortunately, I can't find cement boards at K-rauta where I usually shop, only these -->

Best regards, Björn

 

[Per i Hamrånge]

Exactly the type of subfloor panels I mean. There is also a third variant which is 6mm oil-hardened "masonite". You can buy 4mm oil-hardened board in large sheets and cut it yourself. It's cheaper, but they tend to sag a bit after a while.