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Thoughts on subflooring

vickark's picture

I'm thinking of using 1 1/8" osb instead of 23/32" osb for subflooring. The 1 1/8" is triple the cost of the 23/32". But I think it would be for a more solid floor.

 It's going over 2"x10" on 16" centers.  This will be t&g osb, glued and screwed.

 Single story, 2"x6" walls  8'

 Any thoughts?

If you're determined to (post #214437, reply #1 of 8)

If you're determined to over-build, you might do better and cheaper (though perhaps more install time) using two layers of the thinner stuff, with the joints offset.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Thats a good idea, I haven't (post #214437, reply #2 of 8)

Thats a good idea, I haven't thought of that. Thanks

Why? Joist size and (post #214437, reply #3 of 8)


Joist size and spacing will have more affect on floor stiffness and strength than the subfloor. 

2x12 with 23/32" subfloor will be about 40% stiffer than what you are asking about.

My suggestion would be to use (post #214437, reply #4 of 8)

My suggestion would be to use a higher grade of subfloor, like Advantech.  I don't see a need for something an inch thick on a residential floor.

I don't see the need... (post #214437, reply #5 of 8)

"I don't see the need for something an inch thick.."

I do. The OP has not told us what kind of flooring material he plans to use. If tile, he wants AT LEAST an inch of substrates below the tile.

As a general rule I favor building up in two layers. With the top layer staggered over the bottom layer, and top layer butt joints set 4' away from bottom layer butt joints, the floor has a better chance of being "self leveled". If he truly wants/needs a perfectly flat subfloor, it is possible to smooth out high spots and fill in low spots after the first layer is installed. Better yet, run a power plane over high spots on the floor joists before  installing subfloor. 

Mel Fros

If I were too... (post #214437, reply #6 of 8)

If I were to do an upgrade on a subfloor and spend more money I would us Plywood instead of OSB.  I think Plywood is stiffer, less mold prone, less likely to swell with moderate amounts of water (all will swell if flooded).  In short, OSB suckks, whether 3/4  or 1 1/8.  This is coming from one who has used the OSB and just wish I had gone old school.  And oh yes EVERYONE will tell you ... use the OSB... that is the standard.  Yes, standard for money saving cheap job.

My opinion.  Others have theirs.


40 years ago. (post #214437, reply #7 of 8)

40 years ago we built a house with 3/4 ply and 5/8 partial board on top.  Solid flat floor.  THen I bought a house build just a few years after the forementioned house, and it had only 3/4 ply under the carpet.  I have never noticed a difference.  So do you need thickness? 


I agree plywood is far better (post #214437, reply #8 of 8)

I agree plywood is far better than OSB.