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Subfloor leveling…

IronDog | Posted in Construction Techniques on September 22, 2002 03:01am

Hi All,

I am looking at installing a 3/4″ t&g wood floor over a 3/4″ subfloor. The subfloor has a dip in it that is about 8′ across and is about 1/2″ deep. Has anyone used floor leveler for something like this?
Leveling of the joists is not possible by the way.
Thanks in advance!

tom

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  1. Piffin | Sep 23, 2002 01:31am | #1

    Yes you can use leveler but note that some brands like for you to build thicker spots in layers no more than 1/8" or 3/16"

    Even if you can't get to work on the joists, I would definitely be absolutely sure they are not still going. Add support or whatever, even if it means cutting up a small section of subfloor. Therre is a reason this sag is there so if you don't fix the boo-boo, it'll only get worse. Sounds like somebody didn't know about crowning joists or it's a really old one that has been overloaded for too many years.

    Excellence is its own reward!
    1. User avater
      IronDog | Sep 23, 2002 12:42pm | #2

      Thanks Piffin,

      I'll look into those issues.

      Tom

    2. JohnSprung | Sep 24, 2002 02:07am | #11

      I second Piffin's motion to check out the joists before proceeding.  How old is the building?   Is this floor over a crawlspace? a basement? occupied rooms?  Is the sag the result of previous remodeling downstairs?  Is the subfloor OSB, ply or plank?  If it's plank, are there gaps you can poke a screwdriver thru and check the joists for termite or dry rot damage?  Am I asking too many questions?  ;-)

      -- J.S.

  2. ANDYSZ2 | Sep 23, 2002 01:21pm | #3

    I have used floor leveler dozens of times under carpet but I am not sure you can nail hardwood flooring down over it because it would crack or even bend the nails. you might have to shim up with carpet pad or something else.

                                                                       good luck,

                                                                      ANDYSZ2

    1. Piffin | Sep 23, 2002 02:51pm | #4

      Maybe with thick coat of cementious but using say, Durhams rock hard water putty would be fine. twenty minute set time.Excellence is its own reward!

      1. ANDYSZ2 | Sep 23, 2002 03:30pm | #5

         Piffin

             How big a quantity can you get that and does  it mix up like soup so that it self levels.

                                                         ANDYSZ2                         

        1. Piffin | Sep 23, 2002 03:44pm | #6

          You could order it in 55 gal drums if you wanted. I get it in tins about two pound, I guess at the yard. Lots of flooring suppliers carry it.

          You can mix it soupy. The more water you add, the weaker it can be. You can also mix it stiff as putty to fill nail holes in vertical surfaces if you wanted too. It's easy to mix and work with,Excellence is its own reward!

          1. ANDYSZ2 | Sep 23, 2002 03:48pm | #7

            Piffin, now if  I can only find it I'll check out the floor supply places.Sorry about the loss of your dog.

                                            ANDYSZ2

      2. whancock64 | Sep 23, 2002 08:30pm | #8

        Isn't Durham's the best?!

        1. Piffin | Sep 23, 2002 10:55pm | #9

          Having not used all there is, I wouldn't know for sure but it's likely to be first I reach for.Excellence is its own reward!

          1. whancock64 | Sep 24, 2002 01:39am | #10

            Once, while learning things the expensive way, I used Bear 50/50 to level a small depression in the floor. I think it was something like $35 or $40 just for that one spot!

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