Don’t skip this step! Otherwise, you may discover the hard way that your homeowner’s insurance doesn’t cover injuries that occur on a deck that isn’t permitted and built according to code.
In the U. S. , call 811 before you dig.
While the deck’s structure is typically made from pressure-treated lumber, you have several options for the decking boards you’ll be walking on. You can use a range of natural woods like cedar or redwood, composite (blended wood and plastic) decking, or PVC decking, to name just a few options. Many big-box home improvement stores and decking material producers offer free online deck design tools. Because this is an elevated deck, you’ll have to include railings in your design. You’ll also need stairs, unless you’re building more of a balcony-style deck that doesn’t have direct access to your yard.
Remember to factor in the thickness of your decking boards, which will rest on top of the ledger board, when determining the height of your deck in relation to the exterior door you’ll use to access the deck. To reduce the chance of water infiltration (and to keep leaves from blowing in), it’s best to have the tops of the deck boards about 3 in (7. 6 cm) below the door threshold. If you’re building the deck off the first level of your home, locate the bottom of the ledger board at least 1. 5 in (3. 8 cm) above the top of the concrete, stone, or brick foundation. This prevents water from leeching up from the foundation into the ledger board.
In most cases, the opposing board will be a mirror image of the ledger board—the same size, dimensions, and type of wood.
Repeat this joist-marking process on the ledger board’s opposing board as well. Since the joists will support the deck flooring and provide structural stability, proper spacing based on your design and weight-capacity needs is important. In general, deck joists are spaced 2 ft (61 cm) apart.
Generally speaking, deck footings are spaced about 4–6 ft (1. 2–1. 8 m) apart, and rarely if ever more than 8 ft (2. 4 m) apart. Depending on where you live, your local building inspector may need to check the holes for depth before you can continue. Remember to call 811 to have your utility lines marked before you start digging.
Choose a concrete mix that’s intended for use in footings and mix it according to the product instructions.
Use anchor bolts that coordinate with the metal post bases you’ve chosen to use to attach the deck posts to the concrete footings.
Post bases are designed to keep the wood posts from coming in direct contact with the concrete footings. Without them, moisture will wick up from the concrete into the wood and may cause it to rot prematurely.
Regularly check to confirm that the posts are level and square. Temporarily hold them in the proper position with braces made of scrap lumber. Cut off the tops of the posts to the correct height once all of them are in place.
Continue to regularly check for level and square as you work. If you’re using pressure-treated lumber, brush some end-grain sealer onto the cut ends to help prevent rot.
Tap the joists into place with a hammer if it’s a snug fit between the joist hangers. However, trim off a bit of the joist instead of bashing at it with the hammer in order to squeeze it into the hangers. The joists need a bit of room for natural expansion and contraction with the weather.
If you’re using composite or PVC decking, you might be instructed to use a special decking jig that allows you to drive screws or nails into the sides of the deck boards instead of straight down from above. This makes the fasteners invisible once the deck is complete. If your deck is wider than your deck boards, cut the boards so they join right over a joist. Stagger these joints with each row of deck boards so they don’t all end up on the same joist.
Add the skirting board before installing the railings and stairs. Or just skip this optional element and move on to those components of the deck.
Cut notches into the bottoms of the 4 x 4 (or similar) posts so they will partially rest on the decking and partially overhang the deck. Secure the posts through the skirting board and into the rim joists or beam with at least 2 lag screws or carriage bolts per post. Carefully measure the spacing between posts, then cut and assemble the top and bottom rails and balusters as a unit. Attach each section of railing and balusters between the posts with 3 in (7. 6 cm) screws.
Use math (perhaps with the help of an online design tool) to design stairs that meet your local building code—for example, deck stairs often need to be at least 36 in (91 cm) wide, at least 10 in (25 cm) in tread depth, and no more than 7. 75 in (19. 7 cm) in height per step. Cut the left, right, and center stringers (the supports for the stair treads) out of 2 x 12 boards and attach them to the deck structure with corner brackets, L-brackets, and 3 in (7. 6 cm) deck screws. Cut the risers (the vertical part of each step) and attach them to the stringers with deck screws. Trim 1. 5 x 10 tread boards to length and connect them to the stringers with 3 in (7. 6 cm) deck screws. Add posts and railings in the same way as those on the deck, but this time factoring in for the angle of the stairs.
