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  1. #1

    Default new construction to old,leveling out floor

    Greetings All,

    Im not new to the forums, just new to being a member. I have found alot of useful info on here, and thank you.

    my current project involves a house built in 1947 and attaching a new addition to the existing structure. as with old houses its not quite square and level and attaching the new does present some interesting issues. not major, but just require some opinions.

    I need to mate up a new construction floor to old construction. since the new will be level I need to level out the old to it. basically the old is higher in the centre and drops about 1/4" over 11 ft to the outside wall. I thought about using self leveling then a 1/2 ply on top for a nice new surface for a smooth transition from old to new.

    I really dont feel like lowering the centre of the house since I think this will throw off the dynamics of the rest of the house.

    your thoughts?

    G

  2. #2
    Join Date
    Feb 2008
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    Northwest Indiana
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    5,576

    Default Re: new construction to old,leveling out floor

    Being only 1/4", deal with it after the shell is up and you getting ready to finish. Your method should work well, just keep the added thickness in mind as you're framing.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  3. #3
    Join Date
    Apr 2008
    Location
    Kennett Square, Pa (chester county)
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    476

    Default Re: new construction to old,leveling out floor

    1/4" isn't that bad. I've seen new houses worse. Like to said, let it go until finish. What type of flooring?
    Darrel Hunter

    "You can't build a reputation on what you are going to do." - Henry Ford

  4. #4
    Join Date
    Jun 2004
    Location
    St Louis, Mo for the past 25 years
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    7,581

    Default Re: new construction to old,leveling out floor

    despite the fact that I might be called a hack but I do not know if I would be too bothered by 1/4 inch in 11 ft. For much of construction I would think that could be accepted without too much problem. I know lots of folks like self leveling but I am not a big fan of the stuff. Have seen it crack many times under stress and when placed on top of flooring, especially when you start to get to the really thin portions.

    Like Tom said, keep it in mind once most of it is built and figure out if you can live with it.

    This is a good question and I am waiting for other answers. I have struggled with how you build it, level or to match what is there.

  5. #5
    Join Date
    Feb 2008
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    Northwest Indiana
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    5,576

    Default Re: new construction to old,leveling out floor

    Beez,

    If you have issues with SLC cracking, use plastic lath. Mapie is the brand I use.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  6. #6
    Join Date
    Jan 2005
    Posts
    9,252

    Default Re: new construction to old,leveling out floor

    3/16" variance in 8' is the standard tolerance for many flooring types. I'm with Mark if the 1/"4 is gradual over that 10'...

    I never had issues with SLC cracking unless the subfloor was not stable..
    “Racism is man's gravest threat to man - the maximum of hatred for a minimum of reason.”
    Abraham J. Heschel (Jewish theologian and philosopher, 1907-1972)

  7. #7

    Default Re: new construction to old,leveling out floor

    thanks All for the replies.

    I will be installing ditra and tiles on the new/old construction. I may be incorrect with how much its is out. possibly 1/4 - 1/2" over 11 feet. I see no issue with the SLC and then adding the ply on top, then ditra and tiles. I just wanted to see if there are alternatives to the solution I had in mind. Im always looking for a better solutions.

    I just want to get a near seamless transition.

    G

  8. #8
    Join Date
    Feb 2008
    Location
    Northwest Indiana
    Posts
    5,576

    Default Re: new construction to old,leveling out floor

    You have to prime the sub floor with laytex primer and use lath (I use the plastic lath from Mapie) if you are using SLC over a wood base. I set my tile on the SLC, I would be concerned about the fasteners for the added layer of ply fracturing the SLC. Stiffen the floor pour your SLC, set your Ditra, set your tile.

    Don't forget the in floor heat, pour your SLC over it.

    Check the primer bottle, wood floor 50/50 mix for ply, used straight for concrete. The brand I use anyway.

    Use low expansion foam at the wall plates and check the floor for possible "leaks". Protect lower floors with plastic to collect "drips".

    Use a bow rake with the tines up to massage the SLC. Mix as much as you can at on time. I use the large storage totes or a 30 gallon plastic garage can to mix in. A single pour is always the best way to get this to work.

    Measure water exactly.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  9. #9
    Join Date
    Jun 2004
    Location
    Farmington, Ct.
    Posts
    49

    Default Re: new construction to old,leveling out floor

    When you get to the sub-floor sheathing it would be a good idea
    to weave the panels across the seam where the two buildings meet,
    this will help to strengthen the transition area. In other words,
    don't let any sheets land too close to the building seam.

    Geoff

  10. #10

    Default Re: new construction to old,leveling out floor

    Quote Originally Posted by tjbnwi View Post
    You have to prime the sub floor with laytex primer and use lath (I use the plastic lath from Mapie) if you are using SLC over a wood base. I set my tile on the SLC, I would be concerned about the fasteners for the added layer of ply fracturing the SLC. Stiffen the floor pour your SLC, set your Ditra, set your tile.

    Don't forget the in floor heat, pour your SLC over it.

    Check the primer bottle, wood floor 50/50 mix for ply, used straight for concrete. The brand I use anyway.

    Use low expansion foam at the wall plates and check the floor for possible "leaks". Protect lower floors with plastic to collect "drips".

    Use a bow rake with the tines up to massage the SLC. Mix as much as you can at on time. I use the large storage totes or a 30 gallon plastic garage can to mix in. A single pour is always the best way to get this to work.

    Measure water exactly.

    Tom
    Hmmm... good thinking about the fastners breaking up the SLC. perhaps I could predrill the fastner holes?

    the only reason Im using the 1/2 ply is to transition between the new and old construction. the floor is pretty stiff already with 1.5 t&g subfloor on old and 3/4 on new. it just made better sense to me to get a nice level floor by placing the 1/2 ply after the SLC. perhaps Im wrong. wouldnt be the first time :)

    does this make sense (SLC, ply, predrill fastners, ditra, tile)or am I better off with ply, SLC, ditra, tile. which would give me a nice seamless floor?

    thanks

    G

  11. #11
    Join Date
    Feb 2008
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    Northwest Indiana
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    Default Re: new construction to old,leveling out floor

    Check the Mapie SLC for thickness allowed. Also check Ditra XL.

    I would not put ply over the SLC.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  12. #12
    Join Date
    Apr 2008
    Location
    Kennett Square, Pa (chester county)
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    Default Re: new construction to old,leveling out floor

    I don't think I would sandwich the leveler between two plywoods. I might build up some of the lowest spots with 1/4" ply before the second layer of ply. How big of an area are we talking about that needs to be leveled?
    Darrel Hunter

    "You can't build a reputation on what you are going to do." - Henry Ford

  13. #13
    Join Date
    Feb 2008
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    Northwest Indiana
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    Default Re: new construction to old,leveling out floor

    Forgot to mention, I have put down Ditra in low areas (to decrease the amount of SLC needed), poured SLC over it, placed Ditra over the SLC, then set tile.

    Tom
    http://chicagocraftsmen.org/2011/06/261.html

    Check with the AHJ, what we say doesn't matter.

  14. #14

    Default Re: new construction to old,leveling out floor

    Quote Originally Posted by dlhunter View Post
    I don't think I would sandwich the leveler between two plywoods. I might build up some of the lowest spots with 1/4" ply before the second layer of ply. How big of an area are we talking about that needs to be leveled?
    Thanks for the advice. I will not sandwich the leveler with ply. The area is approximately 240 sq feet.

  15. #15
    Join Date
    Oct 2005
    Location
    Hudson Valley area of N.Y.
    Posts
    621

    Default Re: new construction to old,leveling out floor

    1947 house
    Post war - scarce materials - you say 1.5 subfloor - what are the joists? Tile is heavy. You don't want deflection.
    What size tile are you placing? The larger the tile the more important it is for the floor to be level.
    I just did a similar ( dip in the floor ) Used SLC than thinset cement board to that before tile. Large 20 X 20 tiles worked out well
    Just my 2cents
    Bill T

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