Flooring material for bathroom.

[mariner]

Hi Everyone,

I am in the middle of making a new bathroom off of the new master bedroom - I recently moved to this house and want to improve on the setup. I want to utilize a small adjoining room for the project. I have taken up the old carpet to find that the flooring material used is 3/4" particle board on top of 2" thick boards across the floor joist. As I am wanting to make a bathroom, water/moisture will be an issue. Is there a way of waterproofing the particle board instead of ripping it out and replacing it with 3/4" plywood?

What I had in mind was to lay down 1/4" ply on top of the particle board and then instal ceramic tile on top of the ply. This should give a waterproof floor that would be extremely durable. The other option would be to paint the particle board and then lay lino on top. Of course, the particle board could be replaced but that would cause a lot of extra work and expense and be very awkward.

Any suggestions would be appreciated.

Thanks in advance,

mariner

[Bob NH]

If any water EVER gets to the particle board, it will wreck your floor. The stuff comes apart and expands.

Go to www.johnbridge.com, the premier web site for tile questions. You will get lots of suggestions, and a very big NO NO regarding particle board. http://johnbridge.com/vbulletin/index.php

[Gary Swart]

If you think it would be alot of work now, what will it be like when (not if, but when) the partical board gets wet?

[jadnashua]

Tile may be waterproof, but unless you use epoxy grout, it isn't...also, 1/4" plywood is not typically a viable surface for tile...it must be an exterior grade plywood, with no D face, and if there are C faces, they must be plugged. You will only get a successful tile job on plywood if you use two layers, installed perfectly...no shortcuts, and you use the appropriate modified thinset. Anything else, and the life of your floor will be limited (cracking tile and grout). While your planks may be strong enough to support tile, you need an isolation from all of that seasonal movement...tear the partical board out, install at least 1/2" plywood, screwed to the boards, not the joists, then either 1/4" cement board or an isolation membrane. Make sure to install the cement board (cbu) per the manufacturer's instructions with thinset under it and the screws at the designated spacing. Don't be mislead into the so-called 'thinset' you buy premixed in a tub...NEVER use it in an area that can get wet. Use a real cement based product that you mix yourself.

But, before you do any of that, ensure that your floor joists are stiff enough for a successful tile job. The size of the room you will tile has little to no relationship to whether the floor can successfully support tile. Also, if you decide to use a natural stone tile, the floor must be at least twice as stiff as ceramic.

Highly suggest you go over to www.johnbridge.com and get some expert advice on tiling...it will be worth your while.

[mariner]

Hi all,

Already you have convinced me to rip out the particle board and replace it with good quality plywood. I expected that might be the case but was hoping there might be another approach that would work.

I really appreciate the input. My previous experience with tiling has been on top of cement floors or kitchen counters etc. Will take a loooong hard look at the recommended web site www.johnbridge.com.

Thanks once again for your input - saved me doing the job twice, now and again later :-).

mariner

[prashster]

I can't believe anyone would have put particle board down as a subfloor. It's not structurally safe at all.

Are you sure it's not OSB? The strands or chips are larger and structurally similar to plywood. If it's coated and rated for external sheathing, it'll be as reliable as plywood.

Personally, I wouldn't tile directly over plywood or osb in a bathroom (unless you use epoxy grout). BOTH can swell and warp with water. I'd put down Durock cement board over top of the osb or ply. That'll take any water a little better. Also, it'll keep the floor stiffer which'll protect yr tiles from cracking.