How to Install Composite Deck Railing

Replace your Old Pressure Treated Deck Railing with a Composite Deck Railing System

By Mark J. Donovan

In this video, I show how to install composite deck railing. Previously I had a pressure treated deck railing that had warped, split and cracked, and overall was just an unsightly mess. 

The composite deck railing system I am installing is from Fiberon. The deck railing sections and deck post sleeves are made from a composite material that has a smooth vinyl coating over their outer surface.

Install Deck Posts

To install a composite deck railing system you still need to install 4×4 pressure treated deck posts. 

The deck posts should be attached to the deck frame using either lag bolts or carriage bolts. It is vitally important that the deck posts are perfectly straight and plumb.

Install Deck Post Sleeves

The first step in installing a composite deck railing system is to install the post deck sleeves over the 4×4 pressure treated posts. The deck sleeves should be cut to a length such that they exceed the top of the 4×4 posts by 1 to 2 inches. The deck sleeves should all be cut to the same length, relative to the finished surface of the deck.

After sliding the deck sleeves over the 4×4 posts, slide the vinyl skirts over the deck sleeves. Later on you’ll use PVC glue to tack the skirts in place.

Top Composite Rail Section Centering

Next place the top composite rail section on top of two adjacent post sleeves/deck posts. Center the top rail section so that the two baluster insert holes closest to the edges of the opposite deck posts are evenly spaced.

 How to install a composite deck railing system.

Then mark the top rail section at each end where it intersects the plane of the post sleeves. Cut the top rail section at the marks using a miter or chop saw to ensure straight cuts.

Bottom Composite Rail Section Centering

Then place the lower rail section up against the top rail section that you just cut so that the baluster insert holes line up perfectly. Then draw a couple of marks on the bottom rail section aligned with each end of the top rail section.

Before cutting the bottom rail section verify the distance between the marks with the spacing between the post sleeves at the base of them. Make sure they match.

Attach Brackets to Composite Rail Sections

Next attach the brackets to the top and bottom composite rail sections. Note that the brackets should mount on the underside of each rail section. Before fastening the brackets to the rail sections make sure to mark and drill pilot holes for the screws. 

Deck Installation Bid Sheet

Also, the brackets should be mounted approximately 1/16 inch in from the edge of the rail sections.

Install Baluster Inserts between Top and Bottom Rails

With the brackets mounted to the rail sections, now install the baluster inserts along the top and bottom rails.

Now find the center between the post sleeves and attach the bottom rail support post. There is a screw and small bracket that will need to be fastened into the deck surface. The support post then simply slides down on top of it.

Final Placement of Lower Rails

Next, place the lower rail system onto the top of the support post and while holding a level on top of the bottom rail section locate and mark the positions for the screws to attach the lower rail to the post sleeves. Make sure the rail section is level when marking the position for the screws.

Then drill pilot holes at the markings and fasten the bottom rail section to the post sleeves with the appropriate length screws that came with the composite deck rail system.

Now install the balusters into the bottom rail system and then slide the top rail section onto the balusters.

Again, mark the hole locations for mounting the top composite deck rail section and then drill pilot holes into the composite deck sleeves. Slide the screws into the bracket holes and fasten them into the pilot holes in the post sleeves.

Install Top Cap Covers

Finally, slide the top caps over the post sleeves using a little PVC glue to hold them in place. And with that, you’ve installed your first section of composite deck railing. Continue this process for the remaining sections of deck railing to complete the project.

For help on building a deck, see’s Deck Installation Bid Sheet. The Deck Installation Bid Sheet will teach your how to hire the right deck contractor, and help to ensure that your deck project is completed on time and budget.

Deck Installation Bid Sheet

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