How to Assemble Deck Railings

Mark the post locations for the railing every 4 feet along the deck floor. Use a colored marker to highlight both edges of the 4-by-4-inch post, which will be spaced 4 inches apart, on the desired floor spot.

Cut a notch along the marked post edges on the deck floor if it overhangs the framing, using a reciprocating saw. Remove the wood cutout and discard. Repeat this process for all the posts along the deck. However, skip this step if the deck surface is flush with the frame.

Calculate the heights of the identical posts before cutting these to size. Add to the desired post height the joist height and deck floor surface thickness. For instance, if you want the posts to stands 36 inches tall from the deck surface, add to this measurement the joist height and deck surface thickness. Cut each post to the sum of the measurement using a circular saw.

Measure and mark the sum of the joist height and deck surface thickness from the end of each post. Form a 1½-inch deep notch over the post mark with a circular saw. Position the tip of a chisel against the notched section on the post and hammer it gently to clean the cutout.

Bore two pilot holes through the base of each post for the lag bolts.

Place the first post vertically in the notch along the corner of the deck and drive two 4½-inch screws through the pilot holes to secure it to the joist. Use a wrench to tighten each screw. Repeat the process to install the remaining railing posts along the deck.

Measure and cut 2-by-4-inch lumber to match the width of two adjacent posts. Hold the rail against the upper edges of the posts and drive three deck screws at each joint. Repeat this process to install the upper horizontal rails to the upper ends of the posts along the deck. Also cut and secure 2-by-4-inch lumber for the lower horizontal rails to the posts, directly above the deck floor.

Set a vertical spindle against the upper and lower rails, 3 to 4 inches from the first corner post. Drive two screws through its upper and lower ends to secure it to the 2-by-4-inch rails directly behind. Continue installing spindles to the horizontal rails between the posts, spacing them 3 to 4 inches apart. Maintain uniform spacing between adjacent spindles.