Plywood over particle board - Contractor Talk - Professional Construction and Remodeling Forum

PA woodbutcher · 03-10-2009, 06:07 AM

Searched for particle board and understand that I don't want to go over it with a nailed down 3/4" oak floor....didn't like that anyways.

I am doing the whole bottom floor of a house and have the original part of the house done...There is an addition at the back of the house that is already 1" lower than the original. The addition has 5/8" particle board (with vinyl tile) on top of 3/4" T&G roofers. Original plan was to tear up the particle board and replace with plywood..Have had a ton of "while your heres" and am now running waaaay behind.

Would like to tear off the tiles and throw an aditional layer of plywood on top of the particle board and lay the hardood on top of that. Gets me 2 things. gains me a few days in tearing up the board and saves me from having to make some godawful transition piece. Will be making my transitions anyways so some drop is not a big deal.

Joist strength is not an issue as I have already had to set a beam under the joist in order to take some of the sag out of them.

Only real concern is to eliminate any means of water getting under the plywood and into the particle board...maybe a glued T&G?

SLSTech · 03-10-2009, 07:19 AM

By the time enough water gets through the hardwood & plywood / OSB to swell up the particle board you have bigger issues.

As long as the Particle Board is still in good shape, I always use Liquid Nail & screw the T&G OSB to the joists. I haven't had a problem or issue yet. Any swelling would be limited downwards

woodfloorpro · 03-10-2009, 08:38 AM

Putting plywood over particle board is not recommended. Just think of what the next guy is going to have to do if you're customer does end up with water damage issues. I would present the situation to the customer and explain that you need more time but if you must you need to pass through the particle board into the subfloor at least 3/4 of an inch with nails or staples and NWFA recommends 3/4" plywood. Mike

PA woodbutcher · 03-10-2009, 07:10 PM

Quote:

Originally Posted by woodfloorpro

Putting plywood over particle board is not recommended. Just think of what the next guy is going to have to do if you're customer does end up with water damage issues. I would present the situation to the customer and explain that you need more time but if you must you need to pass through the particle board into the subfloor at least 3/4 of an inch with nails or staples and NWFA recommends 3/4" plywood. Mike

As a remodeler, I generally think of the next guy as I'm usually him. It's not a matter of her time I'm worried about, it's mine. Just had another 3 weeks of work thrown at me and will be balls to the walls until June. Don't think this is the time to be turning work down

The only water that the floor should be susceptible to would be mop water. I've been using rosin paper o the rest of the floors, but no reason that I couldn't use #30 felt instead. 3/4" would also be my choice for plywood..I was leaning towards plug and tough sanded, T&G. Glues in PTSTG are also rated for water contact, glued at the seams it should be pretty much impenetrable.

Any more advice would be appreciated, as always.

astor · 03-10-2009, 10:37 PM

I would at least put 6 mil poly between particle board and ply just in case to protect the ply;moisture transfer from OSB to ply .If the future water damage reaches to that deep, the wood floor would be lost anyway.
Jury is still out for OSB for hardwood flooring, personally I have installed 1000's sq.ft of 3/4" wood floors over OSB with staples over the years and have not even one OSB related call back(BTW:builder specified and had waivers signed to cover me, and still in touch with builder).OSB industry insists it is ok, NWFA recommends ply, but not object OSB either.

PA woodbutcher · 03-11-2009, 06:09 AM

Quote:

Originally Posted by astor

I would at least put 6 mil poly between particle board and ply just in case to protect the ply;moisture transfer from OSB to ply .If the future water damage reaches to that deep, the wood floor would be lost anyway.
Jury is still out for OSB for hardwood flooring, personally I have installed 1000's sq.ft of 3/4" wood floors over OSB with staples over the years and have not even one OSB related call back(BTW:builder specified and had waivers signed to cover me, and still in touch with builder).OSB industry insists it is ok, NWFA recommends ply, but not object OSB either.

No doubt the floor would be lost.

Not sure about the poly though. If I adde poly, that means no glue...not to mention the thousands of holes I'd be punching in it with the staples...Good info on the OSB. Have never been a big fan of OSB except for wall sheathing and prefer plywood for roofs. Don't think I would even consider it for a floor. If the customer is willing to spend the bucks on hardwood floor, what's a couple of extra on plywood.