CSLB C-27 Landscaping ContractorHardscape and FeaturesHard
A landscape contractor is planning to install a new wooden deck using pressure-treated lumber for the framing and joists. The deck will be attached to an existing house. To comply with building codes and prevent moisture damage to the house's structure, what is the most important component to install at the ledger board connection?
- AA layer of roofing felt between the ledger and the house siding.
- BA continuous metal flashing and self-adhering membrane.
- CA decorative trim board.
- DAdditional lag bolts spaced every 6 inches.
Show answer & explanationAnswer & explanation
Correct answer: B. A continuous metal flashing and self-adhering membrane.
Proper flashing and a self-adhering membrane (like a 'peel-and-stick' waterproof membrane) at the ledger board connection are absolutely critical. This system prevents water from penetrating behind the ledger board and into the house's rim joist or wall framing, which can lead to severe rot and structural damage. This is a common point of failure for attached decks if not done correctly.
Why the other options are wrong
- A. Roofing felt offers some protection but is generally not considered sufficient or code-compliant for the long-term waterproofing required at a deck ledger board connection, especially compared to metal flashing and self-adhering membranes.
- C. A decorative trim board serves an aesthetic purpose only and provides no waterproofing.
- D. While proper fastening is important, additional lag bolts alone will not prevent water intrusion and subsequent rot; they only ensure the ledger is securely attached.
Deck Ledger Flashing
A waterproof barrier system installed at the connection point where a deck's ledger board attaches to a house frame, preventing water intrusion.
- Protects against rot in the house's structure.
- Typically involves metal flashing and a self-adhering membrane.
- Mandated by building codes for attached decks.
Memory trick: Where the deck HUGS the house, a waterproof SHIELD is vital to keep rot away.