Second newbie post here,

Going to install 1100 sq ft of eng hardwood flooring over concrete. There are some long cracks in a couple rooms, not super wide, seem pretty normal.

One contractor said they must be filled/repaired first.

Another said no need to repair them, that the 2 in 1 moisture barrier/glue is sufficient to deal with the cracks. This same installer has over 30 years experience, excellent reviews & gave a great estimate. He said if I really wanted to deal with the cracks, I could just use some epoxy.

Advice?
Thanks!

I've seen some glue run down into the cracks. I patch them just because. Most say they can span a 1/8 inch crack. Bostik MVP4 will definetly run down into some cracks and leave a gap. Follow the directions from the adhesive manufacturer.

I'd go with Bostik Ultra-Set Single Step or Sikabond T-21. You can only glue it down once. I've used both on damp slabs.