Self Leveling Compound over Black cutback

Discussion in 'Floor Preparation' started by handyhokie, Apr 16, 2012.

  1. handyhokie

    handyhokie Guest

    Hello out there. First time post.

    I have removed some old asbestos tile (I was careful) from my basement where I plan on laying down tile and laminate in the two different rooms.

    Now I'm left with black cutback covering the floors, and I was wondering what prep work is recommended before putting down self leveling compound. I couldn't get anything- acetone, paint thinner - to remove this stuff.

    These photos give an idea of what I'm working with. Suggestions?

    Attached Files:

    Last edited by a moderator: Apr 16, 2012
  2. Daris Mulkin

    Daris Mulkin The One and Only Charter Member I Support TFP Senior Member

    Want to be careful, the cutback may also contain asbestoes.

  3. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    NEVER use chemicals to clean a surface to which a cement-type tile product is to be installed...NEVER.

    If that floor is scraped down to where there is nothing more than a (cutback) stain in the surface you'll be fine.

    Just remember that ALL SLC's require their own primer. In this case the primer is mandatory. Just be sure the primer is totally dry before going ahead. You have a twenty-four hour window to install the SLC after the primer has been installed.
  4. Omnipotent

    Omnipotent Flying Dutchman

    24 hour after the primer has been dried? I believe that's only the case with epoxy primers. Normal dispersion primers don't really have a maximum open time. Also it is recommended to use a gypsum based levelling compound on bituminous substrates, as it doesn't builds up shrink tension while drying.
  5. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    Here we go !!!

    All primers I have used prior to installing SLC clearly state that the SLC should be installed inside of (within) a twenty-four hour application of the primer.

    Gypsum-based products are never to be used under cementuous applications or under thinset mortar. There was a time when that was being done, but no more.

    When using SLC's prior use of leveling compound is not necessary.

    "Shrink-tension" is not a major concern and the only shrink-tension to be considered is actually the "surface-tension", and that also is not a concern. Small cracks will develop from surface tension but those cracks are not detrimental to any of the subsequent applications to come.

    The only time overall "shrink-tension" is somewhat of a concern is with products like Gypcrete and Gypcrete uses gypsum anyway.

    Gypcrete (containing gypsum) is not a good subsurface for a tile installation and this is why Maxxon has further recommendations for specific applications over their product if the surface is to receive a mortar-type adhesive (tile).
  6. stullis

    stullis Charter Member Senior Member

    Why do you feel you need an SLC?

    Use a trowelable floor patch that is designed to go over cutback.

    Still need to scrape the residue to a thin layer.
  7. Nate Hall

    Nate Hall Types With Elbows Senior Member Published

  8. Elmer Fudd

    Elmer Fudd Administwative Asst. Charter Member I Support TFP Senior Member

    Still need to scrape: From the website.

    Directions: Existing adhesives must be mechanically scraped down to a bare residue flat with the substrate. Do not use solvent or liquid cleaners to remove old adhesive. Floors must be clean, dry and free of any other concrete sealers, curing compounds, wax, oil, paint or any foreign matter that will interfere with a good bond.
  9. Nate Hall

    Nate Hall Types With Elbows Senior Member Published

    Then a GOOD razor sharp scraper can be your friend! Wear gloves or you will have blisters on your blisters. Invest in many replacement blades for the scraper, and you'll be done in less than a month! ( hopefully a lot less than a month )
  10. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    what's actually being leveled?

    you say ceramic and laminate are being installed

    can't tell from the photos what's so severely unflat that you think a self-leveling compound is the way to go

    who are you consulting with--- or what makes you think SLC is the right choice?

    who's going to do the actual install?

    what's the thickness difference between the finished tile and finished laminate?
  11. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    handyhokie must be off doing the Hokey Pokey somewhere.

    You put your right hand in,
    You put your right hand out,
    You put your right hand in,
    And you shake it all about,

    You do the hokey pokey
    and you turn yourself around
    That what it's all about.
  12. handyhokie

    handyhokie Member

    Hello all. I was having trouble logging into the site to respond to people's posts.

    To answer some of the questions:
    - Three rooms are being leveled, all the rooms are connected. One room will have laminate, the other two tile.
    - I decided to level after reading that the floors shouldn't have more than 3/8" dip within 10 feet.
    - I'm a DIYer, I've done everything to finish this basement myself (except for the drywall mudding/taping) myself. I'm learning as I go.

    A lot has happened since I posted. I wet scraped the floor and got it down as smooth as I could (I still have some blisters). Cleaned everything up as well as I could, primed thoroughly, and put down the compound. I don't see any problems with the adhesion, but now I have some bumps that I'm planning to grind down.

    I'm aware of the asbestos in this type of cutback, so I was sure to keep it wet and wore a mask/gloves/goggles while scraping.

    Any suggestions are appreciated. I'll try posting pictures.
  13. handyhokie

    handyhokie Member






    Last edited by a moderator: Apr 23, 2012
  14. Omnipotent

    Omnipotent Flying Dutchman

    Nice, what's the layer thickness?
  15. handyhokie

    handyhokie Member

    It depends on the spot, but generally around 1/8 to 1/4"

    Most of it turned out fine, but there is one spot in particular that has a lump. I was checking the flatness with a 10 foot 2x6 and there are still gaps of around 1/4". I even tried lowering the high spot with a grinder, it helped a little but mainly just created a lot of dust. So I decided to put some more leveler down around that area. I'll see how that turns out tonight.
  16. Demonseed

    Demonseed Pro Member

    Looks good, you are hired.
  17. stullis

    stullis Charter Member Senior Member

    All that work and still have 1/4" spots. SLC has become the biggest waste of money for DIYers :(
  18. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    To cover areas that big the installer needs to use a gauged-rake (screed) to move the material around. Otherwise the material has a tendency to stand proud at some of the marriages of the product. "Self Leveling" can be a little misleading because the product does not "self level" technically in the extreme sense.

    Trying to place only a 1/8" cover is usually a mistake, you really need it to be a little thicker for it to work in your favor.

    If you go over new SLC with another pass of new SLC don't forget to prime first or the product will flow slower than the first time and you could have a helluva mess.

    SLC has a slight learning curve and I agree with stullis.

    SLC is one those great products that you to have used at least once before, before you use it for the first time.:rolleyes:;):rolleyes:

    Personally I love the stuff and have had great success with it.
  19. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    I agree with Bud and stullis.

    Handyhokie, your NEXT job will come out much better.

    Yes, I'm joking. You done OK.
  20. handyhokie

    handyhokie Member

    Thanks for the help. I guess... :eek:

    Last night I tried another round of grinding the high spot, and primed/SLC around it to try and get it more uniform. I haven't been able to check how it came out, but I have a feeling its still not going to be perfectly level.

    I'd say 90% of the floor turned out great, the two adjoining rooms are flat, its just this one area of the main room thats giving me problems.

    What are my best options at this point? I'm not too proud to call in a pro, but I don't know if anyone will want to come in just to fix my un-level floor.

    I'm in Rockville, MD if you guys know any local pros who could help me out. Thanks.

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