sub floor problem

Old 04-06-06, 02:58 AM
Visiting Guest
Posts: n/a
Angry sub floor problem

Hi, Iím having a problem with a fairly new floor that I recently installed. I have a split level house and the lowest level has a concrete floor with 2x4ís on top of that as floor joists, then there is particle board on that. Then there was carpet and pad over the particle board. Last fall we decided we needed new carpet in this room. There was previously a leak in the roof (20 years ago) that came through the room above and damaged some of the particle board, so there was so unevenness in the floor where the new particle boards were replaced (before I bought the house). So after I removed the old carpet I decided to put a layer of ľ inch plywood over the whole floor to try and even out the floor (overlapping the seams). I had the new carpet installed and it looked great. But now the floor seams to be warping/buckeling in spots. I didnít notice any problem all winter when my boiler was running, but since it has warmed up some and the boiler isnít running as much is when I am noticing the problem. I am not sure if there is a vapor barrier under the original floor. Is it possible that the particle board and carpet was working as a sponge and absorbing the moisture for years? Now that I have plywood on top of the particle board, is the moisture getting through the particle board and warping the plywood? If this is the case is there any solution other than pulling up everything and putting plastic over the concrete. This room is about 4 feet below ground level, and I have never used a dehumidifier in this room, and not sure if that would help.
Old 04-06-06, 08:54 AM
Join Date: Dec 1999
Location: Oromocto, New Brunswick, Canada
Posts: 261
Received 0 Votes on 0 Posts
Repairing sub-floor

We work in the disaster restoration business (fire and flood).

Any time we run across a sub-floor that has been damaged by water, we pull up everything and replace with new. This eliminates the possibility of the situation you are now facing.

Particle board will absorb moisture and swell up as a result. This will push up the plywood covering you installed.

When we install new flooring, we use pressure treated lumber that will contact the basement floor and 5/8" T&G plywood. We screw the plywood every 6" and "Hilti" the 2X4's to the basement floor. Extra work and cost? Sure, but out floors will still be there when the house falls down.

Old 04-06-06, 01:53 PM
Visiting Guest
Posts: n/a
So, should I rip out everything, carpet, sub floor, and the 2x4ís (floor joists) that are lying on the concrete, and put down plastic (if there isn't any already) before I replace everything? If so, I believe the 2x4's are probably under the existing walls in this room. It would be very difficult to replace one at a time if I need to put plastic under them.
Any ideas?
Old 04-06-06, 02:20 PM
Join Date: Mar 2006
Location: Great Barrington MA
Posts: 532
Received 0 Votes on 0 Posts
I hate to say it but my suspicions lay with the 1/4" you put down. Maybe it wasn't glued/screwed enough and is now coming up? Is there an ongoing moisture problems since the origonal leak was resolved? OSB plywood (chip board) falls apart with minimal exposure to water. I really don't like it for anything. Roof sheathing perhaps, but makes lousy decking. I guess the only real options are to try to tack down what's loose, live with it, or the best way, tear it all up and do it again. The code I am familiar with only allows pressure treated lumber to come in contact with concrete. Be it joists, sole plates, whatever. It is unfortunate that new carpet has already been put down. Would not have been so bad before that. I wouldn't worry about a vapor barrier if there is not a big moisture problem. Plastic can trap small amounts of moisture that is bad for your concrete deck over time. Good Luck!

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: