Q: Is glue down or nail down better for engineered wood flooring? This is for a 2nd floor/upstairs.
A: Clearly it is much easier to nail down a floor than to glue it down. The adhesive approach is generally used when installing over concrete. Also some adhesives act as acoustic barrier and some as moisture retardant. This latter should not be an issue on the second floor and if sound transfer is an issue their are membranes that can be laid out first, such as cork.