Building a Deck Addition

Building the Deck Footings and Substructure

Actually building a deck addition starts at the footing level. Deck posts should rest on concrete pillars or footings that are sunk into the ground below the average annual frost line. The deck posts should be mechanically fastened to the concrete pillars or footings.

Next mount the deck posts to the concrete pillars or footings and use temporary braces to hold them in place. Make sure the deck posts are plumb and level. After setting the deck posts, use a mason’s line to mark the level for trimming the deck post heights. Run the mason’s line from the top of the ledger board to each post and mark each post appropriately for cutting. Note that the height of each deck post should be equal to the ledger board minus the depth of the beam or band joist board that will set on the posts.

Use cross beams between deck posts to add additional strength to the deck substructure. Use lag screws or bolts to tie the cross beams into the deck posts.

Mounting the Deck Ledger Board Once the footings or deck pillars and substructure are in place the main deck construction can begin. A ledger board is fastened to the home to support one end of the deck floor joists. The house siding and trim should be removed where the ledger board is to be fastened to the home. The ledger board should then be lag bolted to the home’s band joist. It’s important to include flashing above and below the ledger board before residing the house to prevent water from seeping behind the ledger board. As an alternative to removing the house siding for the deck ledger board, there are mounting brackets that are now available that mount over existing clapboard siding. The mounting brackets are lag bolted into the band joist via the siding and then the ledger board attaches directly to the mounting brackets.

Installing Deck Floor Joists and Deck Railing Posts

Next install joist hanging brackets, on 16 inch centers, along the length of the ledger board and the beam or band joist. Then slide deck floor joists into the hangers and fastened them with non-corroding type nails.

After installing the deck floor joists, install the deck railing posts. To ensure solid deck railing posts use lap joints and lag screws or carriage bolts to secure the posts to the deck joists. Also, install additional framing blocks around the deck posts for added rigidity.

Rest the bottom of the stringers on either a wide concrete pad or on individual concrete pavers. Adjust the height of the pad or pavers accordingly so that the stringers are level across each other. Then fasten decking boards to the stair stringers.

Building Deck Railings

With the deck posts already in place, all you need to do is build the deck railing members to slide in and install between the posts. There are many styles and ways to build deck railings. One of the easiest solutions is to install 2×4 rails between the deck posts near the top and bottom of the posts. Balusters can then be fastened either in between or to the outside edge of the 2×4 rails. If your desire balusters in between the 2×4 rails, first mount the balusters to lattice material, with the balusters properly spaced. Then simply fasten the baluster framework in between the deck rails using non-corroding nails or screws.

With the deck railings in place your deck addition is complete. Simply stain or paint it and it is ready for use.