Deck replacement: what to know
Signs your deck needs work
- Soft spots. Push a screwdriver into boards, joists, and posts. If it sinks in easily, the wood is rotting.
- Railings that wobble or move when you lean on them.
- A ledger nailed to the house, or with no metal flashing above it.
- Rusted or missing joist hangers, bolts, and screws.
- Posts sitting on the ground or on loose blocks, or footings that have sunk or heaved.
- Joists that bounce, sag, or have split.
- Stairs with loose treads, uneven steps, or no handrail.
Why the ledger matters
The ledger is the board that fastens the deck to your house. It is a common failure point when decks collapse.
Older decks were often nailed to the house with no flashing. Water got behind the ledger and rotted both the ledger and the house framing. Today's code calls for bolts or approved structural screws, and flashing that sends water away from the house.
Resurface or replace?
If the frame is sound, new boards and railings on the old frame can save money. That only works when:
- Joists, beams, posts, and footings are solid, with no rot.
- The ledger is bolted and flashed correctly.
- Joist spacing suits the new boards. Composite often needs joists closer together than old wood decks used.
If the frame fails any of those checks, replacing the whole deck usually costs less over time than patching it, and the new deck is built to current code.
Replacing only railings or stairs
Wobbly railings and worn stairs are often the first parts of a deck to fail. If the rest of the frame is sound, they can be replaced on their own and built to today's code, often in a day or two. Railing posts and stair stringers that have rotted at the bottom usually mean the framing they attach to needs a closer look too.
What today's code asks for
Pennsylvania towns enforce a building code based on the International Residential Code. Many older decks were built before these rules. Common items:
- Guards (railings) wherever the deck is more than 30 inches above the ground, at least 36 inches tall, with gaps too small for a 4-inch ball to pass through.
- A ledger bolted or screwed to the house and covered with flashing.
- Footings below the frost depth your township sets.
- Stairs with even steps, a handrail you can grip on any run of four or more risers, and a light at the stairs.
- In many designs, metal connectors that tie the deck to the house framing so it can't pull away.
The American Wood Council publishes a free guide, DCA 6, that shows these details for typical wood-framed decks. Your township's inspector has the final say and may add local rules.