Old particle board subfloor

[STraveler12001]

So, I want to redo the floor in a cheap little cabin. The subfloor is particle board, covered with linoleum tile, subsequently carpeted. I've removed the carpet and tile (shingle rake was helpful for that). The particle board has gotten wet in some places and softened and gotten lumpy, and doesn't smell very good. I'm thinking of trying to seal it with some sort of paint or varnish or something, before putting a plank floor on. Something that would soak in and harden and restore some integrity to the soft spots, and seal in the musty smell. Anyone have an idea as to what might work, or general advice on dealing with particle board subfloors?

[Edwin Pawlowski]

It is already crap. Replace it. Any shortcut now will be a big deal later. Could be moldy if it stinks.

[Eric9822]

I agree with Edwin. Rip it out and replace it. Better to do it now before you invest a lot of money putting new flooring over it only to have to rip it out later.

[Tony Hwang]

Hi, Very, Very Ditto! Do it right and forget it long time.

[Paul MR]

Is it adequate simply to replace the soft lumpy section (about 6 sq. ft. near the sink in my case) or do you advise replacing the whole underlayment? What material is best to use under vinyl tiles instead of particleboard?

Paul in San Francisco

[Meat Plow]

Yeh I would have to agree. Get it replaced now before you regret it later.

[Edwin Pawlowski]

I'd use plywood. Yes, just cut out any bad spots. glue and screw the replacement. Glue helps prevent squeaks later.

[Norminn]

I have tried to repair damaged particle board on cabinets and counter tops - it is trash. Once wet, in my experience, it is a pile of sawdust. I would tear it up and replace - moisture barrier and marine grade ply? I'm no expert on plywood, but have had my share of floods, damp conditions, etc. If the cabin is without heat or AC for periods of time, I would also try to finish the ply to keep moisture out. Top off your work by caulking around perimeter of the floor, so the next leak/flood is contained. Enjoy :o)

[scott21230]

If I were made dictator, I'd execute anyone who used particleboard for floors. Rip it out. All of it. And replace it with plywood.

[scott21230]

I would also coat the plywood with oil based polyeurethane before putting the flloring material on it. Then again, I'd do the same with a roof.

[DerbyDad03]

Devil's Advocate checking in...

Define "cheap".

Determine the cost of replacing the entire floor with plywood, finishing the plywood and caulking around the perimeter and compare it to the value of the cabin itself. Is it worth it?

Consider the condition of the rest of the cabin. Are there other parts of the cabin that are also poorly built and will need repairing in the near future? If cost effective, it might make sense to include those "uprades" as part of this project. If not, it might not make sense to put extra money into upgrading the entire floor in an otherwise crappy building.

Consider the construction method of the cabin. Are the exterior walls built on top on the particle board subfloor and if so, what is the condition of the particle board under the exterior walls? Will you be replacing the interior floor section, while the integrity of the building itself is in question because the floor under the walls is rotten?

At the highest level, I agree with everyone else that a particle board subfloor sucks and that it should all be replaced with plywood. On the other hand, the cost of the new floor has to be weighed against the value of the building (before and after) to see if it makes sense.

[TH]

If I was worried about moisture, I'd go cement board. But if the OP just replaced the particle board that was bad, and used sheet vinyl instead of vinyl tiles, just making sure the edges were well glued, I doubt he see any more problems.

[Jeff Wisnia]

The local radio commercials for Reeds Ferry Sheds:

Claim that unlike the Big Box sheds, their sheds don't use particle board floors, because when particle board gets damp it becomes........

Fall apart-icle board!

(Worth a drum roll and rim shot, eh?)

Jeff

[barry]

but floor of particle-board. In this context, linoleum, carpet, whatever does not count as flooring.

3/4" of plywood/whatever for the only flooring would be kinda cheap and bouncy. I'd go for nothing less than double-layer. J

[sylvan butler]

That's what I'd do. I strongly recommend putting a sealer over the entire subfloor to minimize these problems. I used Zinser's BIN (pigmented shellac) but polyurethane is probably better.

I prefer plywood, but under vinyl many people prefer the smoothness of particleboard. NOTE that you are going to need to fill the entire floor so it is perfectly smooth -- no nailholes, chips, stuck on bumps, etc.

sdb