DIY Network

Building a Deck

How to Install Floor Joists and Deck Boards

Having established the deck perimeter, the floor joists are finished and the redwood decking is attached.

More in Outdoors

  • Time


  • Price Range

    $250 - $500

  • Difficulty

    Moderate to Hard


Step 1: Measure for Joist Placement

Begin by measuring for the first joist placement — 24" from the end of the attached ledger board. The remaining joists are also attached at 24" intervals. All the joist members must sit flush with the perimeter boards, so use the 2" x 6" wood block template to precisely line up the first of several joist hangers (Image 1). With the hanger positioned, nail it into the ledger board (Image 2). Then connect a hanger opposite the perimeter in the same manner.

Step 2: Place the Joists

Cut a raw 2" x 6" board to length on the chop saw (Image 1), and then slide the joist into and between the two hangers. As you hammer side nails through the hanger and into the joist, have someone apply top pressure by standing on the board (Image 2). This trick-of-the-trade helps prevent the boards from squeaking later when they are walked on.

Step 3: Snap a Chalk Line

Normally we would set the remaining joists in the same manner, but with the sloping concrete slab obstructing the space in our example, we must make a few adjustments to each board. After cutting the board to length, snap a chalk line that transfers the concrete slope (Image 1). Then use a table saw to carefully rip the board to a taper following the chalk line (Image 2). Instead of sliding this now tapered joist between two hangers, only use a hanger for the end of the board that attaches to the outer rim joist. Toenail the tapered end of the joist directly to the ledger board, and then in place of a hanger, place a small board next to the joist for vertical support and screw it into the ledger board (Image 3).

Step 4: Install the Deck Boards

After setting the remaining joists in the above manner, install the deck boards. Crafting the first board to fit over the ledger board and along the uneven edge of the house is critical to the look and stability of the remaining boards. Having measured around the front face of the house, mark the first board and trim to width using a circular saw (Image 1). To fit along the house, cut out notches using a jigsaw (Image 2).

Step 5: Use a Power Screwdriver

To permanently set the deck boards, use an auto-feed screw-driving tool. This handy device makes quick work of screwing in the planks in an upright position as opposed to stooping. To set the first plank, stand on the board and drive screws through the joist below (Image 1). Adjust the distance between planks depending on the climate. In a dry climate, the boards will shrink. In a moister climate they will swell. Address any warping boards by pushing the board down with your foot as you screw (Image 2).

Step 6: Bolster the Roof Overhang

For this deck, we are also bolstering the support posts for a sagging roof overhang. Instead of sitting on the concrete slab, the posts now sit directly on the new deck surface.

new support posts for roof sit directly on deck