Trex Signature stair panels are installed in a very similar way to horizontal panels. They do, however, need to be racked, the cutting can be a little more complex, and you have to install the brackets on the posts. 

Step One: Racking Trex Signature Stair Panels

Racking means changing the angle of your railing panels to accommodate the angle of your stairs. This is why there are no pre-mounted brackets on stair posts — the angle determines the necessary bracket height.

To begin properly racking your stair panels, locate a piece of scrap decking. Mark and cut it to fit snugly between your posts, running along the nose of your stairs. This will be your platform for marking and will help you determine the correct bracket height. 

From here, you can determine what angle your stair panels need to sit at. 

Now it's time to set the panel. Place your railing section on top of your scrap decking board and adjust to work out the correct placement. Look for even spacing between the baluster and post on both ends, and make sure your balusters are running parallel with your posts. 

Step Two: Clamp and Mark Your Trex Stair Panels

Clamp and mark your panels, making sure the space between the post and the closest baluster is equal on both sides. Remember to measure at a right angle to posts, not at the angle of the stairs and railing. Adjust if necessary and measure again. 

Step Three: Mark Bracket Locations

When your spacing is correct, mark the location for your brackets on your posts. To do this, use a pencil to record where the bottom of the rail intersects your post. Repeat at all four meeting points of post/rail. 

Step Four: Cut Your Trex Signature Stair Panel to Size

Take your stair railing over to your sawhorse to cut. Straighten the panel out before cutting so the rails are running away from you directly at 90 degrees, then clamp. Cutting at this angle will help you to avoid running into the rails as you cut. 

Move each cutting mark ¼ inch in to accommodate bracket size. Transfer the mark to its new location with your speed square for accuracy. Again, use a circular saw with a fine blade to make all four cuts. Your brackets will cover the cut straight-cut edges once your Trex stair panels are fully installed. 

Step Five: Install Brackets and Align Panel for Fastening

Remember, the posts on your stairs don't have brackets yet. These are key before you attach the railings to your stairs. 

To install the brackets, extend the line you marked on your post in pencil and place the bottom of a bracket on top of each line. Mark the screw holes in each bracket with a pencil and remove the bracket to drill pilot holes where you have just marked. Again, use your 7/64 inch drill bit. 

Next, place the brackets and use the stainless steel screws provided to attach them to your posts where the top and bottom rails of your stair panels will sit.

Step Six: Align and Fasten Your Stair Panel

The final step for installing your Trex Signature Stair Panel is racking the panel again, making sure it is at the right angle for your deck stairs and also fits into your brackets. If it doesn't fit when it is at the right angle, you might need to recut your panel or adjust the positioning of your brackets. 

When racked, set the stair panel into place. Then, drill through the side of the brackets and into the rail. Finally, add your bracket covers and the stair panel top caps and post caps. Installing these is the same on a Trex stair panel as it is on Trex horizontal deck railings. 

Finally, if you have scuffed or scratched your Trex railings or stair railing while assembling, you can order spray paint or a touch-up pen.