Decking over decking
Can a new deck go right over the old one?
My outdoor deck is 23 years old, and it was built with pressure-treated pine. The surface doesn't look very good, so I'd like to go over it with 5/4 red cedar or 1x6 treated pine. I'd appreciate your comments on this project.
— Joe Molinaro, Danbury, CT
Tom Silva replies: Don't do it. Going over existing exterior decking with new boards will trap moisture and encourage rot. The best approach is to remove all the old boards and replace them with new decking. This also gives you a chance to inspect areas vulnerable to rot, such as the tops of the joists and the ledger. If you find a problem, you can repair or replace the joists as necessary and make sure the ledge flashing is intact.