How to Install Composite Decking and Railings

Cut the posts to length according to your plan and local codes. The bottom ends of the posts will be flush with the bottom edges of the rim and end joists.

This deck has deck anchors attached to the joists, which makes for a stronger railing.

Along the end joists, use deck screws to attach extra bracing between the floor joists and end joists to mount the anchors. Cut the bracing from the same 2 x lumber you used for the joists (for this deck 2 x 8 lumber).

Begin installing posts along an end joist. Screw a post in place, making sure it's plumb and extends to the bottom of the joist.

Mark the joist at the center of the post about 2 inches from the top and 2 inches from the bottom.

At the marks, drill two bolt holes through the end joist and post.

Insert the carriage bolt in the top hole, place the anchor and tighten the nut and washer.

Attach the anchor to the bracing with screws.

Secure a second bolt through the bottom hole. Each post should have two carriage bolts, but will only need one anchor.

Attach an anchor on the back of the bracing for added strength.

Continue installing posts. For posts in the corners, add bracing around the post and secure it with anchors. Again, cut the bracing from the same material you used for the joists (in this case 2 x 8 lumber).

Along the rim joist, add similar bracing behind the posts with screws and corner brackets, then secure the posts with carriage bolts.

Set your first board down and push the groove over the clip prongs.

Next, at every joist, insert a clip prong fully into the board's groove and secure with screws.

Line up the grooves on the next board with the prongs and push the board tightly into place. Overhang the boards by a couple of inches at the end joists. You'll trim them later. Continue installing the composite deck boards. Use a jigsaw to cut the decking and work around the posts as needed. You can make the cutouts a bit wider to help fit the boards in place. You'll cover the gaps later with post skirts.

The last board might not need to be full width. Rip it — cut along the length of the board — to fit if necessary. If you're installing skirting, leave a 1-1/4-inch overhang. Set the board in place and attach with composite decking screws. Later you can cover the cut edge with a fascia board.

To trim the deck boards to length, snap a chalk line along the end joist and cut along the line with a circular saw. Leave a 1-1/4-inch overhang if you're installing skirting.

At the center of the deck, cut the decking to fit the parting boards.

Secure the parting boards in place with composite decking screws. Use a screw to set a drainage gap.

Glue post sleeve collars in place with PVC (polyvinyl chloride) cement. Follow the package instructions.

Measure the distance between posts and mark both ends of each bottom rail 1/4-inch shorter, keeping the baluster hole spacing even between the marks.

Measure and mark the top rail in the same way.

Cut the rails to length.

Use PVC cement to secure a crush block centered on the underside of each bottom rail. Allow the glue to cure.

Slide the brackets and flanges onto a bottom rail. Hold the rail in place, trace the brackets on the posts and then remove the rail.

Reposition the brackets and flanges on a post and mark the holes. Drill pilot holes and secure the flanges with screws. Follow the same procedure on the other post.

Put the end balusters in place as guides and set the top rail in place. Mark the bracket location and install the flanges as you did on the bottom rail.

Insert all the balusters and then lock the top rail in place. Attach post caps with PVC adhesive.