One or Two Layer Subfloor?

15 years ago

Wd it be unusual to have our framer put down two layers of plywood over the joists (one Â¾" and one Â½"); that way, the Â½" layer can be removed at exterior thresholds to get doors to fit with finished flooring a lot better?

Also, it seems the joints between the two layers could be staggered to give more rigidity to the floor, too. Various Sturd-i-floor 4x8 panel makers claim their products replace subfloor and underlayment in one product, but is a two-layer system better (specifically, will it offer a better linear deflectance value?)

And how does one achieve a squeak-free floor if using a two-layer system?

Thanks for feedback, Mark

Comments (3)

mightyanvil
15 years ago
What is the finish flooring?
mark_g
Original Author
15 years ago
A large part of the flooring will be Â½ or Â¾ stone tile, part ceramic / some Â½ porcelain tile, balance Â¾ hardwood. We want to achieve a barrier & threshold-free floor t-out -- no visible or discernable changes in floor elevations, and reduce exterior door thresholds.

Oh, and staple underfloor radiant heat.

--Mark
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worthy
15 years ago
A 1 1/4" subfloor will be overkill for hardwood, just adequate for stone. (I'm assuming at least 2x10 joists @ 16" o.c.)

But it will be necessary for what you're trying to achieve.

Instead of doubling up on plywood, I've used Ditra decoupling underlayment. To reduce squeaking floors, I glue, nail and screw down all subfloors. I-beams instead of dimensional joists would also help.

I went to great efforts on one place to ensure the various flooring surfaces were level. When I sold it, I was so proud of this detail. Buyers could care less, so I don't do it anymore.