Carpet tile on concrete, remove old glue?

Discussion in 'Floor Preparation' started by Trf, Mar 7, 2016.

  1. Trf

    Trf New Member

    Hello all. I'm not a flooring guy, more of a grease monkey. I've installed duraceramic which went well but had a pro lay carpet upstairs. Now the wife wants me to put the carpet tile she bought in the basement which I think I can handle. I've removed all the old crappy carpet which was glued direct to the concrete. The den and Hall was glued entirely while the bedroom was only glued partially. My question is about removing the old yellow glue. Does it all have to come off to the bare concrete? Can I scrape off what I can leaving what won't scrape without hardcore effort? I have about 500sq ft.
    The carpet tile I'm putting down is felt backed and I have Shaw 5001 pressure sensitive adhesive.
    Thanks in advance.
     
  2. Steve Olson

    Steve Olson Hardwood/Laminate Guru Charter Member I Support TFP Senior Member

    Opinions may differ, but I scrape off what I can and float over the residue with Ardex feather edge.
     
  3. kwfloors

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

    And then maybe a primer after that.
     
    • Disagree Disagree x 1
  4. Jim McClain

    Jim McClain Owner/Founder Administrator

    I agree with the 2 jokers above - 'cept I'd scrape, then primer (I used to use Lee's Everseal), then Ardex Feather Finish.
     
    • Like Like x 1
  5. Trf

    Trf New Member

    Well so far scraping has been a nightmare! This stuff isn't coming off well at all. Do you guys really think I need to skim ardex over the whole 500sq ft?
     
  6. Jim McClain

    Jim McClain Owner/Founder Administrator

    What are you using to scrape? I would use a razor-type scraper, keep it at a steady low angle to the floor and slice into the glue, not bump head-on into it. Change blades when they get dull, they're cheap. If a wide scraper (8") doesn't work, try a medium (6") and if that doesn't work, use a 4". The smaller the blade, the longer it will take, but it's doable.

    It doesn't have to be bare concrete, but it should have no glue ridges left. Seal the floor after you scrape and clean, then skim coat the whole floor with the Ardex. That's a very thin layer that will make the floor very flat and smooth. Carpet is much more forgiving than vinyl, but the floor still needs to be smooth so the PSA and carpet bond well. Do NOT use a larger trowel notch, thinking you will help the adhesive grab the carpet better. Follow the instructions.
     
  7. Incognito

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

    Yeah, that's best Steve but not what I see in the commercial side. Enhancer (felt) back is laid over existing glue with no special prep whatsoever. If I had to guess I'd say many, many millions if not billions of square yards have been done that way since Enhancer back came around.

    Lucky if they even sweep it. Maybe you're not aware that the glue works both as a broom and as floor patch. Rookie! (G)

    I shit you not.
     
  8. Mike Antonetti

    Mike Antonetti Senior Member

    I like the felt back of the squares, if I were to recommend carpet tiles in a basement, that's the backing "breathable" to allow moisture to pass.

    Describe adhesive on floor as chalky or gooey. As said best if scraped to even level as slab which is called ?

    Basically your not mixing ingredients of two chemicals, the latex and the acrylic along with the moisture that will mingle the two together. Time will tell if they are compatible if you do not remove most of latex adhesive.

    Ardex skimcoat feather finish isolates the two but usually thicker for complete isolation (1/8") for warranty work. Most things are judgement calls based on our experience and how far we want to go. Here's a felt back job we did recently, zero risk for failure, adhesive from many years ground back to slab.
     

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  9. Steve Olson

    Steve Olson Hardwood/Laminate Guru Charter Member I Support TFP Senior Member

    Have yet to see that Enhancer backing up here, yet. As far as sweeping up before glues goes on, well, that's how I thought you could tell the difference between a vinyl mechanic and a carpet guy. The vinyl guy has a broom...
     
  10. Incognito

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

    If you are ON or BELOW grade it's more critical to address possible moisture and alkalintiy issue with a carpet tile install than for glue down carpet. Both the multi-purpose and the glue down carpet allow moisture to pass through relatively easy. There are really few failures compared to resilient flooring or carpet tile. When you use a pressure sensitive carpet tile adhesive that's going to TRAP moisture. Yes Mike, the felt back can allow moisture to pass but I've seen plenty of instances where the pressure sensitive glue reacts HORRIBLY with the alkaline salts coming up with the moisture-----and that's many years later that the original glue down carpet performed fine.

    Now both the mulit-purpose and the pressure sensitive are brewing up in a chemical slop that stinks to high hell and dissolves both glues over time. This is MUCH worse when it's a hard vinyl backing but it's still a concern with Enhancer backing.
     
  11. JPfloor

    JPfloor Pro Member

    Yep....

    Main reason I like to skim coat is to avoid wasting/running out of glue...:cool:
     
  12. Trf

    Trf New Member

    I'm using a 12" hand scraper with a 4" razorblade. I'll try take some pictures to show what is and isn't scraped.
     
  13. Nate Hall

    Nate Hall Types With toes I Support TFP Senior Member Published

    If the old glue is not powderized, it's on the way to becoming powder. No glue will hood to powder. Get rid of the old glue! As hard as it is now, it will be much harder to deal with after the tiles start to loosen.
    Then use the skim coat to give the new adhesive something to hold on to.
     
  14. Mike Antonetti

    Mike Antonetti Senior Member

    Nate, that is another concern of mine. Putting fresh latex adhesive over the top of latex adhesive, it's done very frequently, with carpet replacements over many years. Then we come in with pressure sensitive system. Not that I mind removing because I'm charging for it. But yes, I have thought about say the original install, 2nd install, etc. about those losing bond.

    I pretty much grind everything now, just cleans easier. This terrazzo will never look nice, the colors are blah, but it has a sealer, pad glue ridges etc. and I would like the pressure sensitive adhesive to dry quicker by absorbing a little into slab.
     

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  15. kylenelson

    kylenelson You'll find me on the floor I Support TFP Senior Member

    Question, has anyone here had a failure from going over old carpet adhesive with pressure sensitive glue?
     
    • Like Like x 1
  16. Nate Hall

    Nate Hall Types With toes I Support TFP Senior Member Published

    I would love to see pics of the resulting plasticizer migration and or resulting chemical goo.
    Pardon the technical talk.
     
  17. Incognito

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

    yes, ON or BELOW grade when you pull up glue down carpet that's been performing fine and then install carpet tiles with a pressure sensitive the ALKALINITY in the concrete sometimes causes failures

    seen it quite often but you need to understand that in the SAME BUILDINGS on the ABOVE GRADE floors (no moisture = no alkalinity concerns) that the same carpet was demoed and the same carpet tile and glue was installed there was never a problem

    I saw this on many occasions and I'm talking tens/hundreds of thousands of yards (including the carpet that didn't fail) over multiple decades.

    GENERALLY SPEAKING you can smear a pressure sensitvie carpet tile glue right over existing multi-purpose without problems that are related to incompatibility or bonding issues.
     
    • Agree Agree x 1
  18. kwfloors

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

    So, what don't you like about that Steve? I have had to re glue because the glue soaked into the porous patch so now I prime to seal the patch so the glue works. Also the tiles I have done over old adhesive there was a primer/sealer to seal off the old adhesive to allow sticky dots to stick.
     
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