Installing Decking

Intro

Decking is a visible element of your project, so install it with care. Naturally resistant woods and KDAT treated lumber will not shrink much after installation, so spacing between them can be about 1/8 inch. Make a spacing jig to speed the job. PT lumber will shrink after you install it, so lay PT boards without any spacing.

You can fasten your first board for parallel decking either at the house or at the edge of the deck, and work toward the opposite side. Decking boards are not all exactly the same width, so you may need to rip the last few boards to make them fit. The width variation may be visible, so it's generally best to install the starter board at the edge of the deck. That way the ripped boards will be next to the house where they will be less visible. Most other decking patterns begin in the center of a module, and you will need to reduce their width as you approach the edge.

To make the decking more attractive, stagger the joints so they do not fall in a straight line. Center the end of the board on a joist and add a cleat to the joist so you won't have to drive a nail or screw right at the end of the board.

Prestart Checklist

Time
Five to seven hours to install decking on a 12x16-foot deck

Tools
Tape measure, chalk line, cordless drill, circular saw, spacing jig, pry bar, wide putty knife, speed square, mitersaw, jigsaw

Skills
Measuring, cutting, driving fasteners

Prep
Install framing

Materials
Decking, fasteners, 1x4 and 8d nails for spacing jig

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Step 1

Measure from the house to the inside edge of the starter board and mark both rim joists at this distance. Snap a chalk line at the marks. The position of the first board will vary, depending on whether you will overhang the decking or install fascia. Make allowances for these details.

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Step 2

To save time, lay out the decking boards loosely on the deck so they're within reach. Plan staggered joints ahead, pre-arranging the boards and installing cleats where necessary. Align the starter board with the chalk line and face-nail or screw two fasteners centered on the joists.

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Step 3

Insert the spacing jig against the starter board and pull the next decking board against it. Fasten this board, moving the spacing jig down its length as you go. Make sure joints are cleated and centered on the joists. Continue installing the decking until you are three boards from the end.

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Step 4

Dry-lay three boards, maintaining spacing. If the last board fits without trimming, install the remaining decking. If not, lay two boards and trim the last one. Or rip the three boards to equal widths. Trim the last board to length for the overhang; you can't trim it in place.

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Step 5

Mark the overhang on the first board and snap a chalk line from this mark to the edge of the last board. Trim off the wild ends of the decking with a circular saw. You can tack down a long straight 2x4 to guide your saw. Bevel the edges with a palm sander, and seal the cut ends.

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Joints over joists

Strengthen each joint by fastening 2x4 cleats on both sides of the joist under the joint. Predrill the decking to minimize splitting, and drive the screws on a slight angle toward the joist.

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Notching a deck board: Step 1

Set the decking board against the post or other obstacle, and mark the edges of the post on the decking. Mark the depth of the notch and square the lines with a speed square.

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Notching a deck board: Step 2

Cut the notch with a jigsaw and test-fit the cut. Fasten cleats on the posts to provide a nailing surface for the inside edge of the board. Fasten the board to the joist and the cleat.

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