Subfloor Problems Looking for A Solution

mlake

I recently purchased a 60 year old house and now notice that the 2nd flloor subfloor has soft spots in pretty much each bedroom (under carpet). I pulled back the carpet to find that the floor is sheeted with less than full sheets (some times patched in ply wood) and they aren't always supported correctly. There are likely 5-10 soft spots in each bedroom, not to mention popping and creeking throughout. The joists appear to be level.

Rather than tear out the entire subfloor (pregnant wife and 3 year old living in the house), I am considering screwing down what is there to make it sturdy and then going over with a new layer of 1/4 cement board or plywood. I was thinking cement board because it is sturdy and it would help with some sound that gets up through from first floor through recessed lights. Again, level isn't my problem and new sheeting diagonal to what is there would be supported well. I would then go back with a nice pad and carpet. Any suggestions or reasons why I shouldn't do this???? Need some big brains on this one. Thanks!

joecaption

Not going to work the way your suggesting.
Adding screw to plywood patches that are not even T & G will do nothing to stop the flexing.
It's not that big a deal to cut out a subfloor and would be the best way to do it.
If for some reason your just not willing to do it a layer of 3/4 T & G Advantec that's screwed down, not nailed would be the next best thing.
Tile board has about 0 strength, would never stop the flexing, in fact it would just crack if it did flex, It's installed for a bonding surface for tile.

woody4249

Don't assume that the only problem here is a spongy substrate to the floor.
I would take up a piece or two and see whats going on under there.
If you find it is just the decking at fault, replacing an entire floor a room at a time is easy if you have a helping hand.

Never use a Band-Aid on house repairs....they only get worse and cost more in the end.
I have to agree with Joecaption

Mike

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