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Home Repair The Old House Flooring

Is Engineered wood okay on top of cement board?

Julia Valenzuela

2 years ago

We had our 1960s step down living room raised (about 3.5 inches) as part of a bigger renovation project, but when it was raised the builders screwed down cement board on top of plywood to finish it off. I'm not exactly sure why because there is no thin set under the cement board but I assume they were trying to have a similar material to our cement slab. Unfortunately the raised floor is anywhere from 1/2 inch to a 1/4 short in places and we are trying to even it out to match with the adjacent cement subfloor. Would it be okay to put engineered wood flooring over the cement backer board? We are considering putting thin-set under the cement board to see if that helps with the height or would it be better to take it off and put down a thicker piece of plywood on top of the other one?

Comments (3)

cat_ky
2 years ago
Remove all the cement board. Replace it all with more plywood, that is the proper thickness to make it level, before you put down any hardwood floors. Thats not what cement board is meant for.
Julia Valenzuela thanked cat_ky
SJ McCarthy
2 years ago
And to add to what cat_ky says, cement board does NOT add to the deflection rating. If you have a bit of a bouncy subfloor under the cement board, then you will CONTINUE to have bouncing subfloor after you put in a floor.

Tell them to take it out (at their expense...unless you SPECIFICALLY signed off on it) and have them put down thicker plywood.

Now here's the rub: the cost of PLYWOOD has TRIPPLED in the last 8 months. What ONCE cost $1/sf now costs $3-$4/sf. I'm going to guess SOMEONE had to save money because the costs they bid at are NO LONGER applicable. If you CHOOSE TO rip out the cement board, then realize you will be purchasing SOOOOOO much plywood you will have paid for a $15/sf solid hardwood floor...and then some.

Be aware that if you already have it down, you will pay to remove it AND you will pay $3-$4/sf for new plywood. That's fine if it is a small 200sf kitchen. It is a MASSIVE hit if you have 2000sf to redo.

Be aware of what you are about to do to yourself or your builder.
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ci_lantro
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23/32 BC sanded pine plywood is around $1.35 per sq ft ($43.28 per 4 x 8 sheet) at my local Home Depot right now. Evidently the price has come down quite a lot.

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