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Underlay Options for Engineered Floor on Concrete/Cutback

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bobmayes2000

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Discussion starter · #1 ·
My first post here - i do electrical work in California and the wife has roped me into replacing flooring in our ~1950's house. Not my main skill set but looking at floating engineered floors (mohawk uniclic).

So i ripped up the existing carpet and parquet hardwood to find sticky black cutback/adhesive. Had it tested - no asbestos and non friable and has tar in it. the concrete floor is level (ranch w/ a slab) but texture exists w/ peaks/valleys around 1/16". Trying to figure out the best way to proceed. I'm not crazy about scrapping/grinding this stuff off and would like to just leave it there.

Any thoughts on how to proceed? Here are the options i'm thinking - any others?
1. Underlayment directly on cutback/concrete. OR put 6mil on the floor first to prevent any bleeding of oils into the underlayment.

2. 6mil plastic w/ 1/4" cork. Seems this would help absorb the texture the best?

3. lay 1/4" plywood, then use a recommended underlayment/moisture barrier.

4. Feather finish over the cutback. Then underlayment. Given the adhesive is fairly thick, not sure there would be sufficient bonding to the glue/concrete?

Appreciate any thoughts. Thx. -Bob.
 
Discussion starter · #3 ·
Thx Mike. That seems to make the most sense. I did call the underlayment company and they made it clear that cutback needed removed. Are they just covering their a**? Said eventually the tar will break down the barrier and the floor will fail. The OAK parquet i removed didn't seem to have any issues other than it wasn't at all sticking to the glue and had gaps everywhere. well beyond the point of a refinish job.

The underlayment is: Sound Solution by Republic Flooring. Maybe there's a better one?
 
#5 ·
It's all a risk, yes the oil may break down the plastic, nuvelle makes a foil backing with a neoprene foam? Some may want you to isolate it with a featherfinish, it's susceptible to moisture , the asphalt will reduce moisture transmission.
Adhesives usually don't bond and will need to be isolated from cutback, Stauf brand has an adhesive directly over cutback that's kinda new if you decide to go with gluedown, we're kinda at the mercy of the scientists/manufacturers.
 
#6 ·
I'd skim it if for no other reason than to eliminate the stickiness. Patch is cheap and I can skim 1000ft in less than 30 min. Makes no sense not to. Once you start positioning underlayment over it, it becomes a pita.
 
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#8 ·
Tech services will say razor scrape to a residue, then apply their appropriate patch.
No need for cork, plywood, the roll underlayment then the wood.
The skim coat is what a pro would do in order to function normally , usually the cutback is from VCT, but if from the parquet the notch may be heavier, one or the other, you scrape it and use less patch, don't scrape you use more.
May get a sticky noise, probably not but theres always possibility in flooring. Standards are usually flat within 3/16" in 10 ft. Rapid drops may need feathered.
How are you going to get out of the next flooring project? Plan ahead!
 
#10 ·
EthanB said:
Holy crap that's fast! What patch do you use? FF?
Click to expand...
Yes. A 2' trowel and 20 years of experience will do that lol. To be fair, I have a guy mixing patch and cleaning trowels for me so I don't have to get off of the floor. You'd be surprised how much time it saves being efficient in your motions. Same thing with installing. Do it once, do it right, and keep the flow going. A 20% reduction in walking over the same area can put a lot more footage down in a days time ;)
 
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bobmayes2000
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