Built-in frame protection
Before a single deck board goes down, the wood that holds the deck up gets sealed. Tape caps the top of every joist and every block, the ledger connection at the house is flashed and taped, and the rim joist gets wrapped completely — face and top. None of it is visible on the finished deck. It is under the boards, working for the life of the frame.
The real thing: the rim joist fully wrapped on a covered deck we are building right now.
Why we do it
- The tops of the joists are where decks die. Every deck screw is a hole in the framing, and every gap between boards drips water straight onto that hole. The tape seals itself around each screw as it goes in.
- The rim joist takes weather from two sides — rain off the deck edge, sun and splash-back on the face. Wrapping it whole, not just the top, protects the board the railing posts bolt to.
- The ledger is the connection to your house. Flashing and tape there keep water from getting behind it — the failure that takes decks down.
- You will never see any of it once the boards are on. That is the point: it protects the frame quietly for decades.
Pressure-treated framingJoist tape / rim wrapLedger flashingDeck boards going down
Illustration only; not to scale.