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How To Install Deck Boards

With your frame completed, it’s time to learn how to install decking boards. Deck boards are usually 2”x4”, 2”x6” or 5 1/4”x6”. Deck boards are laid flat side down and spaced to allow for expansion and room for moisture to slip though. We’ll show you how to lay your deck boards, measure them to fit around posts and finish them by trimming the flush with your deck edge when finished.

Skill Level: Beginner

Before starting any building project check with your municipal office for local building codes, regulations and zoning restrictions.

  1. Step 1 Measure Your Deck

    Measure Your Deck.

    First, decide which way you’ll lay your deck boards. Then, measure your deck and divide by the width of your boards to determine approximately how many boards you’ll need. Add an additional 10-15 per cent to allow for cutting and measurement errors.

  2. Step 2 Choose Boards and Fasteners

    Choose Boards and Fasteners.

    Next you’ll need to choose the type of deck boards you’ll use to finish your deck. Pressure-treated wood is a popular choice because it’s long-lasting, affordable and is infused to make it mould and rot resistant. Cedar is more expensive but usually considered to be a more premium looking deck board, it is naturally moisture and rot resistant looks great. Composite decking is an alternative to  wood and is extremely durable and great for heavy traffic. Holes for deck screws need to be pre-drilled though, making it a bit more work to install. When choosing deck boards, make sure they’re straight by looking length-wise down the edge and checking for bows, as if the board is bowed too much, you’ll have trouble getting it to fit snugly against the other boards. Also make sure that there is at least one clean side with no blemishes, and use that side up when drilling them in place. You’ll also need decking screws, which have a larger head but are stronger than traditional screws. You can even get screws to match the colour of your wood to help them blend in.

  3. Step 3 Mark the First Board’s Position

    Mark the First Board’s Position.

    Mark each rim joist at a distance from the outside of the header joist equal to the width of one decking board. Use a chalk line to create a line that touches all of the marks across the joist and is parallel to your house. Align the inside edge of the first length of decking with your chalk line. It’s ok to let the boards extend past your deck unevenly. You’ll cut them off later. After laying deck boards, drill two screws through the board and into each joist, 3/4 to 1-inch from the edge of the board.

  4. Step 4 Allow Spacing for the Next Rows

    Allow Spacing for the Next Rows.

    Now install the second row of decking. Ideally, with most wood, you want to leave about an 1/8-inch gap between boards after the decking has dried. You can use a spacer to make sure you’re consistent throughout the whole deck. Pressure-treated lumber is usually wet when you install it, so you should install those boards tightly together. The gaps will get bigger once the wood has dried.

  5. Step 5 Lay Out Notch Around Posts

    Lay Out Notch Around Posts.

    Screw a smaller wood block onto the side of the post to support the notched board. Measure the amount that will need to be cut out and then make the cut into the board. Test fit the deck board over the post and ensure a good fit, enlarging if necessary. Once it fits, screw the deck board in like normal and ensure you also screw it into the support cleats.

  6. Step 6 Put In the Last Board

    Put In the Last Board.

    Once you’ve got evenly spaced boards over the entire deck, it’s time to install your last board. If your last board is close to your home or up against a structure, you’ll need to cut it to length, as your circular saw won’t be able to complete the ending trim cut if there is limited room to maneuver.

  7. Step 7 Trim Deck Boards

    Trim Deck Boards.

    With all of your deck boards in place, take a chalk line and snap a line from the back corner of the deck to the front corner on the same side. Then – using that line as a guide – use your circular saw to trim all of the overhanging boards to the same length, flush with the side of your deck frame. Once you’ve got them all trimmed, you’re ready to move on to adding stairs and railings.

Continue to build your deck: Building Deck Stairs and Railing

What You Need for This Project

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