What kind of glue can I use to install my mouldings and stair treads?
You should use a construction adhesive. Apply just enough adhesive to the underside of the moulding and nail it in place with two or three finishing nails on a slight angle until the glue cures. Countersink the nail heads to be filled later. For stair treads, use the same method except that you use 3 finishing nails one on each side, approximately 2 from the wall, and one in the center of the tread.
