Good evening everyone.

I have a 400 sq. ft. living room and I plan on installing BR-111 5/16th engineered hardwood floor. Given the thickness (or lack thereof) of this product and the frailty of the Gypcrete underlayment, I am considering installing a layer of 3/4" thick plywood overtop of the Gypcrete to give a more solid feel underfoot.

I would like to know the pros and cons of installing this layer of plywood, and whether or not it would be a wise decision.

Please advise.

Thank you.

I don't see where that would be cost effective or help any unless the gypcrete needs to be flattened out a lot. From your other post you will be floating the BR-111, correct? I would recommend sealing over the gypcrete to encapsulate it. Someone on here suggested a product for that but I have no first hand experience installing over gypcrete.

Correct. The BR-111 will be floated.

Screed to flatten the substrate along with filling the cracks, with either ARDEX GS-4 or Dependables GSL.

Follow-up questions:

1. So, the floated layer of plywood is not necessary?

2. Is it necessary to apply the GS-4 to the entire floor, even where it is level and has no cracks?

3. How thick a layer of GS-4 is necessary?

4. Approx. how much does GS-4 cost?

5. How much GS-4 is needed for a 400 sq. ft. room?