How should I attach a new deck to my house?

Answered by Brett Kulina ~ June 6, 2013 ~ No Comments

I want to build a deck off of our house, near the kitchen. I am thinking about attaching it to the house on one side and using cement blocks to support the other side. How should I attach the deck to the house? thank you.

Bill T. - Orlando, FL

Brett Kulina

Bill, it is a wise idea to carefully plan how you will attach the new deck to your house, as this crucial connection point can fail if not done correctly. It is also very important that you understand and follow all of the local building codes that dictate how a deck in your specific area should be built. Two of the most common mistakes that can occur when building a new deck are (1) using inadequate fasteners to attach the deck's ledger board to the house's rim joist and (2) not providing a gap(with metal flashing) between the ledger board and the house, which helps rain water drain off of the deck.

When attaching the deck ledger board to the rim joist of your house, you should use 1/2-inch lag bolts, which are stainless steel or hot-dipped galvanized. The bolts need to be placed 2 inches down from the top edge, and 2 inches up from the bottom edge, of the board and should be staggered along the length of the ledger. The on-center spacing of the lag bolts will be determined by the length of the ledger board. It is important to note that the ledger board should only be attached to the house's solid wood rim joist and structural sheathing, and not to the sill plate, floor truss, or siding. If your house's rim joist is not solid wood, but is a laminated I-joist or some other type of engineered lumber, then you will need to follow the manufacturer's specific instructions for ledger board attachment.

A gap of no more than 1/2" is needed between the wall sheathing and the ledger board to prevent moisture from rotting out the wood, and there are several kinds of structural spacers available that are designed specifically for this task. You will also need to install some metal flashing that can prevent water from getting behind your home's siding by directing it away from the rim joist and deck framing. When installed correctly, your deck's ledger board should remain sturdy and sound for the life of your new deck.

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