Proper Ledger Board Connections for Attached Decks
"Today, we're chatting with our good friend Michelle Yee, territory manager for Simpson Strong-Tie in the Pacific Northwest. We appreciate Michelle working with her colleagues to put together this valuable article on installing safe and code-compliant deck ledger board connections. Take it away, Michelle!"
Whether you’re building a brand-new deck or retrofitting an existing one, concerns about the strength and safety of your deck can be a significant source of tension. Other than the quality of the wood itself, how the members of a deck are connected to each other and to the adjacent structure is the most important thing about the deck. Connections that don’t meet code requirements compromise a deck’s strength and safety.
Be Aware of Local Code Requirements
For decks that are partially supported by an adjacent structure, such as a house, the connection between the deck and the structure is vital. While a bolted or screwed ledger-to-rim-board connection is suitable for supporting gravity loads, in Washington State the IRC 2015 building code requires a connection that is able to resist side-to-side, or lateral, loads. In these situations, tension ties are typically called out to tie the joists of the deck directly to the structure.
Simpson Strong-Tie® DTT deck tension ties are a safe, cost-effective solution, designed to meet or exceed lateral-load code requirements for deck construction.
Enjoy Compliance Flexibility with the Simpson Strong-Tie DTT1Z
The DTT1Z deck tension tie is an easy, economical solution for attaching a deck to a home and reinforcing its resistance to lateral movement. This deck tie has been specifically designed to comply with the 2015 IRC provision for lateral-load connections to a supporting structure, and it allows for deck joist connections to be made to top plates, studs, or headers on a home’s structural framing. This means that the DTT1Z can be installed from the exterior, eliminating the difficulty, time, and additional repair work involved in accessing floor joists by going through finished interiors.
The DTT1Z installs easily by fastening to the narrow or wide face of a single 2x deck joist with Strong-Drive® SD Connector screws or nails, and it accommodates most installation conditions, regardless of the siding type or ledger thickness. This deck tie’s versatility removes the guesswork from installation and makes retrofitting a quick and simple job. The code-listed DTT1Z satisfies the 2015 IRC provision for a 750 lb. lateral-load connection to the house at four locations per deck.
The DTT2Z can be used to satisfy the 2015 IRC provision for a 1,500 lb. lateral-load connection at two locations per deck 2' from the end of each side of the deck. The DTT2Z fastens in pairs to the wide faces of the deck and of the house joists with Strong-Drive® SDS Heavy-Duty Connector screws (included), and the pair are anchored together with a ½"–diameter threaded rod (sold separately).
Both parts are available individually or in a deck installation kit that includes all the necessary fasteners. Also, because steel connectors used on decks and other outdoor structures can be exposed to corrosive elements, both the DTT1Z and the DTT2Z have a ZMAX® coating to keep them protected from environmental moisture and from the corrosive chemicals used in some preservative-treated wood.
Know Your Options for Different Framing Conditions
The IRC prescribes particular methods, but it does not represent all common framing conditions. When other conditions are encountered, Simpson Strong-Tie has a technical bulletin that describes alternative methods of construction. Always be sure to consult your local building official for approval before using any methods not prescribed by the IRC.
With the DTT1Z and DTT2Z, your deck’s connections to the home will be code compliant and corrosion resistant. In other words, while the deck’s connections are handily resisting your deck’s tension loads, you’ll be resting easy.
