dri-core for subfloor in basement studio

Posted: Mon Dec 29, 2003 11:44 am

any potential problems with using dri-core and the like for a subfloor in a basement recording studio?

i would like to do something cheaper, but this seems like the only option that doesnt involve alot of work, and loosing a lot of ceiling height.

i want to put a wood floor down for about half of my basement studio, and ive been told that a 3/4" plywood subfloor over the concrete [with the floor on top of that obviously] isn't acceptable for a basement.

now my basement has no moisture problems, as its a new home, thats under 3 years old. ive done moisture tests and nothing, its dry as a bone year round.

Posted: Mon Dec 29, 2003 12:49 pm

Fevers,

whoever told you that putting a plywood deck down over concrete was a no-no - was mistaken. It all depends on the concrete situation and proper preperation.

We do that all the time, and it isn't a problem.

You do want to make certain you have filled in the low points with some levelastic, and if you have any bad peaks - knock them down with a grinder. You do want the floor to be fairly flat so things align properly.

It's never a bad idea to use a concrete sealer prior to this - and you can drill and attach the plywood with concrete screws - that in addition to PL 400 or 500. Just make certain to pre-countersink the plywood - and just snug down the screws so you don't snap them off.

You won't have any problems with this.

Rod

Posted: Mon Dec 29, 2003 1:07 pm

well the concrete is pretty flat and level in the basement, with a few exceptions where it slopes down, but i was planning on fixing that with some self leveling cement.

im assuming id need to use tapcons to secure the plywood to the floor? what size wold you recommend for 3/4" plywood? [that is ofcourse if 3/4" plywood is acceptable subfloor for a engineered wood floor]

on a side note, would there be any problems with the dri-core panels as the subfloor?

Posted: Mon Dec 29, 2003 1:22 pm

Well my original response related to 3/4" plywood, not the DRIcore.

DRIcore panels are specifically made for concrete installation - but they are not meant to be fastened down - (except for maybe some occassionaly tacks to stop them from shifting) - so i get real concerned with the potential for vibration with this floor system.

As far as the plywood goes - tapcons in the 1 3/4" range should be just about right for 3/4" plywood - that's the minimum embed dimension allowed by the manufacturer. And the 3/16" should be fine.

Rod

Posted: Mon Dec 29, 2003 1:48 pm

yeah i assumed the same thing with the dricore panels.

for a 4x8' sheet of plywood how many tapcons would be needed? 1 in each corner?

could i possibly stud drive the plywood to the concrete? or that just wouldnt work?

also, are there any cheaper options for a subfloor in a basement other then plywood?

oh in regards to the plywood does it have to be a special kind such as pressure treated? i was planning on using 4x8' 3/4" CDX T&G plywood.

Posted: Mon Dec 29, 2003 2:12 pm

[QUOTE]Originally posted by fevers_mirrors:
yeah i assumed the same thing with the dricore panels.

OK - so forget them.......

for a 4x8' sheet of plywood how many tapcons would be needed? 1 in each corner?

1 in each corner starts you - you should have them installed 8" o.c. on the 4' ends - and the same 8" o.c. at a max of 24" centers for the body of the board.

i possibly stud drive the plywood to the concrete? or that just wouldnt work?

I wouldn't reccomend that to anyone unless maybe i didn't like them...... Very Happy

also, are there any cheaper options for a subfloor in a basement other then plywood?

Well - there are many wood floor manufacturer's that don't require a wood subfloor to install their products...... so you don't really "need" a sub-foor over concrete.

oh in regards to the plywood does it have to be a special kind such as pressure treated? i was planning on using 4x8' 3/4" CDX T&G plywood.

3/4 CDX is fine.

Rod

Posted: Mon Dec 29, 2003 8:50 pm

Fev-

Are you using regular 3/4" T&G oak flooring or something like Pergo? With oak T&G you might consider flat 1x4's on 12-16" centers to nail the oak to directly. I've seen this used in multi-story condos; the 1x4 often has a nylon mesh backing that looks kinda like really stiff berber carpet, and helps isolate the 1x from the floor. The whole thing floats on the slab this way.

Another 2 cents. If you do the ply, Rod's screw schedule seems a bit heavy; 35 tapcons per sheet is a lot. I'd go 24" o.c. each direction at most; you might find the sheets are flat enough with less.

Good luck.

Frank

Posted: Tue Dec 30, 2003 6:17 am

Quote:

Originally posted by Frank Lambrick:
Another 2 cents. If you do the ply, Rod's screw schedule seems a bit heavy; 35 tapcons per sheet is a lot. I'd go 24" o.c. each direction at most; you might find the sheets are flat enough with less.

Frank,

The reason I go heavy on the screws (Basically staying with the reccomended pattern for wood joist) is due to the quality of today's materials and the possibility of them wanting to "work".

It's easy when the sheets are going down to draw them into position - but if they decide to "work" and you end up with an area that is bowed up (easy to do in the length of the sheet with fasteners only at the mid span) it is another thing all-together to then draw them down with tapcon screws.

Tapcons tend to be quite brittle - and drawing a 3/4" sheet down 3/8 or 1/2" is going to tend to snap a lot of screws.

So with all due respect for your experience - I (personally) would spend the time effort and extra money (I know the screws are expensive) to install the additional screws.

Sincerely,

Rod

Posted: Mon Jan 05, 2004 12:37 pm

Rod,
I am struggling with the same type of decision - how to finish my concrete basement floor. My basement floor is also completely dry, but I thought I still needed to be concerned about moisture occurring from condensation (i.e. when the warmer room air contacts the cooler concrete) and the potential mold growth. That's why I've been concerned about putting anything directly on the concrete that would trap the moisture and not allow air ventilation to dry it out.

Are you saying that from your experience I should not be so worried about that?

I'd like to put down either real wood parquet or "Pergo" directly on the concrete if there is no concern with potential mold growth. What do you recommend?

Thanks for your advice,

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