is it necessary to seal a concrete floor when laying engineered hardwood floor?
You really need to check with the manufacturer of your flooring but many manufacturers recommend that you cover a two or three foot square area of the concrete with a sheet of plastic with all of the edges sealed with tape so any moisture that might be migrating up from below the slab will be trapped. You let the sheet set undisturbed for 24 to 48 hours. If there is a moisture, you will see drops of water or at least the concrete will be damp. If this test shows no moisture then you don't have to worry about sealing the concrete. In any case most engineered floor systems use a thin plastic foam sheet that when completely taped at the joints serves as both padding and a vapor barrier.
