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Subfloor Repair


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  • Subfloor Repair

    As I've stated in other threads my water heater leaked a few weeks ago. I'm now at the stage where I'd like to start repairing sub-flooring damaged by the leak. Of course the sub floor was put down before the walls were erected therefore in some cases two parallel floor joists will be under floors of different rooms with a wall separating them. I'm suspecting I'm not going to be able to get a piece of plywood underneath the wall to lay flat enough to get it on top of the other floor joist in the adjacent room where the other floor joist is because of the wall. My solution to this problem is to put additional perpendicular and parallel joist blocking in between the floor joists and simply run the plywood up to or partially underneath the wall for wall support then go to the other side of the wall and do the same thing. Is this common practice when dealing with replacing sub-flooring separated by walls or is there a better solution? I've replaced small sections of sub-flooring before, but have never had the problem of two joists being separated by a wall to deal with.
    Last edited by FordMan59; 05-16-2016, 01:54 PM.

  • #2
    Your on the right path, there are a couple of variables that can come into play. The most important would be, "Is the subfloor beneath the wall damaged?", if yes then your task is a little harder as the wall will need to be supported particularly if it is a load bearing wall (for obvious reasons). Most load bearing walls don't fall between joists they typically line up right over two joists.
    To repair under a load bearing wall you will need to raise the wall just a little to push the sheet of ply under the wall, on a typical 3 1/2" stud your going to need to be at the very least 1 3/4" under the base plate (bottom plate).
    Non load bearing walls your going to need to span from floor joist to floor joist or as you suggested above add some blocking between the existing joists flush with the top of the existing joists, this will enable you to push the ply under from either side of the wall.
    Little about a lot and a lot about a little.
    Every day is a learning day.


    • #3
      Thanks Pushkins. This is a double wide mobile home so the only load bearing walls are the front, center and rear walls. I haven't torn out much yet. I tore out a small area and placed a commercial fan over the hole blowing air into the hole to help dry out insulation and floor joists before tearing everything out. I have a construction background, but 95% of mine was commercial and industrial construction, not residential or remodeling. The solutions you gave were exactly what I was thinking, but just wanted to make sure there wasn't a simpler more effective way of doing it. How would you suggest raising or supporting a load bearing wall in order to replace damaged material under the wall? With what I've seen so far I'm thinking there may be damage that extends underneath the rear load bearing wall, but will probably be limited to a section of 8-12' long. It also looks as if there will be damage underneath 2 non bearing walls with a total length of about 15-20'. Right now my major concern is getting everything dried out properly. I don't want to cover up wet insulation and floor joists because of mold/mildew/rotting problems. Do you have any suggestions on things that would help the drying out process? I know I could cut out and replace the wet insulation from the top side once the sub-floor is removed, but that will still leave the problem of the wet joists. If there's any insulation to be replaced I definitely want to do it from the top side so I don't have to cut the vinyl belly pan which would only allow more ground moisture to enter the area below the sub-floor increasing the likelihood of mold/mildew problems.
      Last edited by FordMan59; 05-21-2016, 11:14 AM.


      • #4
        Sorry for the late reply, been one of those weeks.

        Yes , definitely replace any wet insulation from the top side, for the cost of insulation I'd recommend just tossing the old wet stuff and put in new, if it's fiberglass bats, once wet they never function correctly again (compacting fibers).
        As it's a double wide that makes your job fairly easy as the over head load is fairly limited, simply build a temporary wall that spans over the area your working on, for example use a 4 x 4 x 10' post as a ceiling joist brace and support it with some 2x4's every 4' - 5' build the wall far enough away from the house wall so that you have room to work. You will want to cut the studs a little longer than the height - 4 x 4 material ( for example a 96" wall - 3.5" (brace) = 7' 8 1/2" plus lift 1/2" so total stud height on a 96" wall would be 7' 9" ) place them on the floor and wedge them up to the 4 x 4 material knocking them at the top till plumb or enough to raise the home wall just a tad. This will also help you get the old damaged flooring out.
        We use steel adjustable jacks and 2 2 x 8's nailed together (sometimes twin 2 x 10's for heavier loads), that way we don't have to keep building walls and the twin 2 x 8's are 12' so we can span over a 8' length and use full sheets of flooring. you can get them at all the big box stores about $40 each from memory.
        It's seldom worth the effort to remove floor joists (you do the same as above but from underneath obviously ) much simpler to either lay a new one beside the damaged joist or sister it onto the damaged joist.
        As far as the drying process, fan blowing on the effected area is the most cost effective and really a very good option.
        Little about a lot and a lot about a little.
        Every day is a learning day.


        • #5
          I forgot all about this thread until I saw it again today. I finally got a settlement from the insurance company for the damages to the house. As it ended up there had to be blocking added to the subloor, subfloor, drywall, insulation, and linoleum removed/replaced and framing dried/treated with antimicrobial/painted in the master closet (approximately 4'x13'), master bath (approximately 9'x13'). kitchen (approximately 13'x25') and the utility room (approximately 5.5'x6.5'). Dealing with the insurance company and contractor(s) to get an accurate estimate of the damage took longer than to actually get the work done. The insurance adjuster had a company (Servpro) that works with him giving out low ball estimates that gave me the first estimate, $5600. I having a construction background knew they'd left off lots and lots of work from their estimate and ended up getting one from a couple contractors of my choice, their estimates were $48,500 and $28,700. As you can guess my relationship with the insurance adjuster went down from that point on. After I turned in the estimate ($28,700) to the insurance adjuster he waited weeks about cutting checks, one day I finally ended up calling and telling him he was going to settle up that day or I was getting the state insurance commission involved. He started saying he wanted to look over the damage again, I told him that was fine, but I had an estimate from another contractor for $48,500 that we could work off of. Within a hour he was at my front door with a check and he wasn't interested in taking a second look. All that's left to do now pertaining to the insurance company is getting a laundry service to give me an estimate for bagging and cleaning molded/odor ridden clothes that were in the closet and an estimate from a gun smith for damages to my guns that were in the gun safe in that closet. I posted estimates amounts in this thread to inform others that might run into this in the future that just because they have insurance doesn't mean their insurance company/adjuster won't try to screw them. I think it's pretty bad when a person pays big money for insurance on their home and when they have a loss the insurance company tries to get out of paying for the full damages. I let the insurance adjuster know that whether the owner did the repair, a contractor did the repair, or the damage wasn't repaired at all there was damage to my property and I intended to collect for the damage. I told him if I wanted to buy a truckload of beer with the money it was none of his business and I'd use the money as I saw fit.
          Last edited by FordMan59; 09-05-2016, 01:22 PM.