Could anyone tell me how to laminate the stairs to avoid noises. I used underlayment and nose to install the laminate stairs, but there is lot of squeaky noise when step on the, especially at night. Should I use glue or nail? I heard no underlayment is necessary. Is it better to use underlayment? Thanks.

Laminate, especially the snap kind, can be very noisy on stairs. Beside the noises you describe there can be a clacking noise just from your shoes. I would glue all the boards down but first beef up what was in place before the laminate. Add additional nails to all surfaces and use construction adhesive in a caulk glue to caulk all seams with glue. If you can get to the underside of the bstairs check to see if they deflect when a heavvy persons walks up and down, if so then brace from underneath. Now glue the lainate in place. The less you walk on the stairs for 48 hours the better.