"Spongy?" floor

Old 04-16-05, 09:22 PM
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Question "Spongy?" floor

Greeting everyone...

My dilema : I am preparing to install a laminate floor in our ground set double wide mobile. The floor of the mobile is "spongy" in places (deflects when stepped on).... most often between floor joists. The floor is 5/8" particle board (8'x14' sheets, yeah wow!!!) on 2x8 floor joists on 19.2" centers spanning the 14' on each side of the house. The under the house metal beam supports look like they are about 2' from the edge of the house and the center of the house, so I'm guessing they are 10' apart (so the 2x8 joists are spanning 10 foot at most).

What is the best way to tackle the "spongy" floor?

I have received the following opinions from family and friends:

Option 1: Install additional support beams under the house making the distance the 2x8's span about 5 feet instead of the current 10' and adding 3/8" or 1/2" plywood to the particle board.


Option 2: Install 1/2" or 5/8" plywood over the existing particle board, using glue between the 2 layers and screwing every 4 to 6 inches.


Option 3: Remove the existing particle board ( ) and install additional floor joists or bridging between the current floor joists and the install 5/8" or 3/4" plywood in place of the particle board.

I am personally leaning toward the 2nd option, but I would like some other advice, or maybe an idea I haven't listed here.

Thank you for your time and advice...

Old 04-17-05, 06:30 PM
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Hello and welcome aboard!

I would advise removing the particle board, just junk and shouldn't be allowed for used as subfloor IMHO, only thing I can think of that it's suited for is cheap wally world furniture and speaker boxes.

I'd rip that junk out and burn it, then install yourself a decent subfloor. I'd suggest two layers of 5/8" plywood.

Sorry to burst your bubble.
Old 04-17-05, 08:05 PM
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Awesomedell is right about that stuff being junk, and the way he describes would certainly be the BEST way. However, unless the particle board is actually rotton, Option 2 would also be a workable solution in my opinion, but I'd suggest glueing and screwing 3/4 t&g plywood or t&g OSB on top. Added strength is what you need, and since the 5/8 particle has none, the 3/4 would certainly stiffen it up between the floor joists.

An additional 1/8" in height shouldn't be a big deal.

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