1/4 Ply pops and cracks, should install be halted?

Q: We are putting in 7/16 engineered hardwood. The contractor tore out our old floor and tile, put down Auquabar “B” underlayment, and then stapled down 1/4 ply. This was so that the new floor would be the proper height for our other floor tile in the home. He has yet to put down our wood flooring as it is acclimating to the house. However the 1/4 ply that we are walking on pops and cracks.

I do not want my new floor to sound like this. Our old floor did not make noise. the contractor tells me that when they nail and glue down my new floor it will be fine. But I feel like something isn’t right. Thoughts? I do not want to move forward and find out the prep work was done incorrectly. They did not fill gouges or level the floor. I was told that was not what installers do and that the new 1/4 ply would cover all the gouges from the tile tear out.

A: I would not expect cracking and popping of the plywood. I don’t know what is under that and the vapor layer but he best make sure that is absolutely secure before he starts installing the engineered because it will be as solid as the surface it sits on. If the sub floor moves it will also.

Follow-up Q: Thank you for your response. The ¼ ply is stapled to our existing sub floor. We have a raised foundation and crawl space. So I believe our existing sub-floor was 3/4 inch plywood. Not sure why they put the Aquabar B down in between as the surface is dry.

It feels like the new ¼ “(measures less), is flexing in spots and we can lay a straight edge and see that we have high and low spots. They tell us they will glue and nail the floor solid!, Also that we do not need paper between the new engineered and the ¼”. I thought you had to have some sort of barrier between the wood?

A: The aquabar, though I’ve not worked with it is the vapor retarder or membrane. The adhesive itself will do nothing to make the floor solid if it is attached to a surface beneath which is not secured. Having said that the plywood is only 1/4″, probably poplar and it simply provides a smooth surface. It would likely flap about a bit. It’s usually used for vinyl floor installations. If they feel confident their cleats will go through all this and give good grab on the original plywood subfloor then it should pull everything tight. I’d still be inclined to bang in a few ring nails. Just keep an eye on it without putting the workers under a lot of stress. Show them your concerns and then the responsibilities are on them. Get it in writing if that would make you feel better. That shouldn’t offend them because it is our job to earn the home owners trust. I do believe everything will be fine. I personally like to remove any doubt if I can.

Follow-up: Thank you, I believe that given how uneven the sub floor is due to tear-out of old tile and hardwood, The holes should have been filled and even out. The engineered wood manufacturer confirmed that the specs need to be followed for a warranty to offer any coverage, should a problem arise down the road. They want paper a vapor barrier between the sub floor and their product. Not under a new layer of sub-floor. No wood on wood they say. So I think it’s best to stop the project. Thank you for your help.

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