Subfloor - replace or beef up?

Repair help for the do-it-yourselfer.
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Posts: 15
Joined: Thu Apr 07, 2011 10:11 am

Fri May 27, 2011 6:53 am

I recently bought a 1970s double wide in Florida. The subfloor is OSB and has soft spots. The carpet is old and nasty. I know the place is water-tight now - no leaks from walls or ceilings. I want to put in good quality vinyl floor - the roll type- in the kitchen and bathrooms.

I am also going to put a garden tub in the bathroom, a water bed in the master bedroom and a set of built-in bookcases in the living room. Naturally, I want to beef up the floor.

Since this is Florida, I won't be able to insure the place for more than the (very low) purchase price, so putting a lot of money into the unit isn't sensible. Depending on the age of the mobile home in Florida, your insurance coverage can be limited and only one company in the state offers it for a unit this old. I also figured since mobiles are being given away down here, that I'd never be able to sell even a nicely finished place.

Would putting 3/4 inch plywood throughout - on top of the existing OSB - be a reasonable approach? I don't want to have to deal with having to level off patched sections. I also have a terrible sense of balance these days and am afraid of falling off the joists and breaking a leg, so I'd be hiring day labor for any needed removal of the full floor OSB.

And if I can just layover plywood, how difficult is it to build up the through-the-floor AC/heating ducts?

I've built 2 houses (with my family) from the ground up, and restored an old Victorian on my own, so I have the skill sets to do most of the work myself. I will need to hire day labor to help with the muscle work since I am an aging and rapidly becoming decrepit reg. nurse. (Hence the desire for a water bed and garden tub with jets!) :wink:

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Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Fri May 27, 2011 5:13 pm

If you are going to do the job, do it right the first time. Remove the old sub floor and replace it with plywood or at the very least OSB. 3/4" is plenty to support what you have.

If you have soft spots now they will not get any better over time. What usually happens is over time the old sub floor will give way creating a void under the new sub floor.

"If I can't fix it, I can screw it up so bad no one else can either."

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Joined: Sun Feb 25, 2007 11:57 pm
Location: Fresno, CA

Fri May 27, 2011 11:02 pm

Soft spots and uneven old sub-floor repairs can be repaired. The subfloor really isn't the issue with items like these as the wide base of the waterbed would be on a minimum of 3 floor joists. That direct connections is what supports the weight, not so much the osb or ply in between. All but the newest mobile homes have 2x6 floor joists, most 16 o.c. some 24" o.c. You will usually have a double 2x6 rim joist. With mobile homes, especially older ones, there could have been roof, siding or plumbing leaks that have deteriorated the connection at the floor joist to the rim joist. Even if all 2x6's were in good condition, a waterbed is still a lot of weight for most older mobile homes. A couple of piers, maybe a beam and definitely some added blocking between floor joists would do a lot to strengthen the floor for weight.

I am thinking you could replace your osb floor with 3/4" or 1 1/8" Sturdi Floor, or just repair what you have. Layering subfloors brings on it's on list of problems such as water getting trapped between layers, floor squeaks, transitions at doors and cabinets. You would have to pull off a countertop to replace or repair the dishwasher.

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All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.