In this video, This Old House general contractor Tom Silva shores up an old deck with new supports.
Steps for replacing a deck post
- Install temporary 2x4 posts beneath the outer deck beam.
- Cut free any diagonal bracing with a reciprocating saw.
- Pry out the nails securing the existing vertical posts to the deck frame. Pull out the old deck posts and discard.
- Set a metal post base on top of the concrete pier, then drill a ½-inch-diameter x 3-inch-deep hole down into the pier with a hammer-drill and carbide-tipped masonry bit.
- If there's a metal pin or rod protruding from the top of the concrete pier, cut it flush with a reciprocating saw.
- Secure the metal post base to the concrete pier with an expansion anchor. Tighten the anchor with an impact wrench.
- Cut a new post to fit between the post base and underside of the deck frame. Fasten the post with galvanized hanger nails. Install one post under each corner of the deck.
- Use metal hangers to attach existing lattice panels or rails to the new posts.
- Stretch a tight chalk line between the two corner posts. Position the line 16 inches down from the top of the deck beam.
- Measure down to the chalk line at a midpoint between the two corner posts. If the midpoint dimension is 16 inches, then you know the beam is straight.
- Cut and install a post between the two corner posts. If the beam sags down, cut a post long enough to raise and straighten out the beam.
- With the new posts securely fastened in place, remove the temporary 2x4 posts.
- Install 2x4 diagonal bracing between the posts and deck beam. Secure each brace with 3-inch decking screws.