Using sleepers to level a floor

Discussion in 'Floor Preparation' started by DaveNJ, Mar 3, 2013.

  1. DaveNJ

    DaveNJ Member

    I would like to install hardwood over a plywood subfloor that is out of level by as much as 1.5". A structural engineer has designed a way to reinforce the subfloor from beneath to strengthen it.

    After much research and discussions with the structural engineer, I plan to have a carpenter or flooring company level the floor by placing 2x4 ripped sleepers on top of the existing subfloor and then adding another layer of 1/2" plywood on top of the sleepers. The sleepers will run parallel to the existing floor joists and perpendicular to the hardwood that will be installed. I will have to adjust some doorways because of the added height, but it will be manageable. On top of the new layer of plywood I will have solid hardwood installed.

    My questions to the floor pros are -
    1. What is the max spacing I can use between sleepers?
    2. Is 1/2" plywood going to be adequate?
    3. Do you see any potential problems using this approach or have any other recommendations?

  2. Jim McClain

    Jim McClain Owner/Founder Administrator

    I don't understand the necessity of installing a sleeper system on top of an existing wood subfloor system. Cut the subfloor panels out, sister 2x6 joists to your existing joists (only make these level), then lay 5/8" or better T&G subfloor panels over that. If you do it right, your height increase should be no more than 2¼". It will be stronger than a sleeper system and only a little more expensive. A sleeper system would still require the same number of "joists."

    You do know that flooring should be flat and that doesn't mean it's always level, don't you? Maybe you don't need to bring the low side up all of 1½".

  3. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    I agree with Jim on the repair, what is the reason for not correcting the joists?, I'm no authority or consultant, just an interested installer who comes across this problem every now and again, and the opportune time to correct is before flooring gets installed.
  4. DaveNJ

    DaveNJ Member

    Hi Jim,
    We originally wanted to cut out the existing subfloor and sister the joists, as you suggested, but there is an interior load-bearing wall that runs lengthwise across the floor. The structural engineer advised against cutting the plywood around it because he says the plywood is helping to distribute the load of the wall across the adjoining joists. That's why we reverted to the sleeper sytem idea, which was a second choice. The other approach we considered is to use self-leveling compound but that would be too heavy because the floor is so far out of level in some places.
  5. Jim McClain

    Jim McClain Owner/Founder Administrator

    16" OC.
    No. Five-eighths or better tongue and groove - it's just like another subfloor.

  6. kwfloors

    kwfloors Fuzz on the brain Charter Member I Support TFP Senior Member

    3/4" T&G plywood over sleepers would get you back to a normal floor. Anything less would give too much.
  7. Kman

    Kman Tile Expert I Support TFP Senior Member Published

    I don't understand this part. If the wall is perpendicular to joists than cutting the subfloor around it shouldn't matter. If it's parallel to the joists then there should be blocking between the two adjacent joists to support it. If not, and the only thing holding up the wall is the subfloor, then you have another problem. A load bearing wall should have more support than just the subfloor.

    Regardless, I'd want to know why the floor has sunk an inch and a half, and fix that problem before going any further. If it's stabilized, then Jim's idea of sistering the joists is the better idea.
  8. eaadams

    eaadams Sport Floor Pro

    In gyms this is what we do with this issue: [ame=]Arenaflex sports flooring system - YouTube[/ame]
  9. DaveNJ

    DaveNJ Member

    @Kman, Good question. The wall is perpendicular to the joists. The joists are actually engineered floor trusses and the building is a condo. The floor sunk because apparently the trusses were not adequate to support the weight of the interior wall. To address this, the home owner's association sent in their strucutural engineer and contractor who reinforced the trusses with plywood gussets but the HOA was unwilling to jack up the floor for fear of causing other structural damage. So,... I am left with a reinforced, sagging floor. Because the floor was not jacked-up, I am left with fewer options for leveling it.
  10. DaveNJ

    DaveNJ Member

    Thanks eaadams. I will check out the website.
  11. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    While I can understand the HOA not wanting to create more damage I doubt the re-positioning (jacking) of the structure would create substantial damage. If the original floor structure was sagging due to the addition of a wall being supported by the floor structure then this should be a warning to someone and it should be realized that the structure was in fact built originally using minimum standards.

    I think I would want a structural engineer to tell someone (me) that the gusset-improvement is in fact going to allow the addition of more static load and to what limits. The engineer should then sign-off on this particular improvement (and bless it) before going forward. If the floor structure is sagging then something else (structurally) has been altered along the way and should have been corrected. HOA's aren't always known for their ability to reason sensibly.
  12. eaadams

    eaadams Sport Floor Pro

    Dave, here is a residential (non sport) product made by Junkers. Junkers is very vertical, the mill owns the contracting corps in the USA so they would probably want to do it for you rather than just sell the items.

    [ame=]Junckers DuoWedge for housing & Commercial use - YouTube[/ame]
  13. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    Good Lord !!!
  14. Floored by Newman

    Floored by Newman Floored by Newman

    Awww the many uses of plastic...made in china?

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