Hardwood over existing hardwood
Is it advisable to install solid hardwood over an existing hardwood floor? We were planning on gluing down engineered floor (opposite direction) over the floor, but like some of the solid floors better. If it is ok to install solid hardwood does it have to be nailed (would buy max 1/2" thick).
I have searched the flooring forums and haven't been able to find an answer. Any advice or experience you can provide would be appreciated!