Expansion gaps for engineered wood floors
 

I am installing an engineered wood floor , 600 squarew fet,. over a concrete floor. I will be using a thin waterproof foam layer first[ don't know that this ios called] andd then laying the snap down tyoe of exgineered flooring.

My questions are
1. Do I need to leave and expansion gap for engoineered wood flooring?
2. If so how much of a gap do I need ?
3. Is this gap left on all 43 sides of the floor of just 2 sides?

1. Yes
2. 1/8" to 1/4" (read instructions on your flooring)
3. All 4 sides.