How to Install Deck Posts on Trex Angles

Measure the framing under the planned post location. Cut two pieces of scrap 2-by-8 lumber with a chop saw to fit between the joists and act as blocking under the post. Place three 2 1/2-inch deck screws into three sides of each piece of blocking, through the rim joist and the two regular joists abutting the blocking.

Lay the leveling plate provided with the Trex post kit parallel to the rim joist, not parallel to the angle of the Trex decking. Nudge the plate gently one way or another so that it lies atop a single angled deck board while also remaining parallel to the rim joist and above its blocking. Drill through the four holes in the leveling plate and into the deck board and blocking with a 3/8-inch drill bit.

Thread the provided 5/16-inch, 1-inch leveling bolts partially through the holes at the center of each side of the post mount. Place the post mount, a tall rod that supports the post sleeve, on the leveling plate. Adjust the bolts until the post mount is plumb, as measured by a spirit level.

Thread the provided 5/16-inch, 6-inch bolts through the post mount, leveling plate, Trex deck boards and blocking. Access the bottom of the deck and press the back plate over the bolt ends and against the blocking. Secure the back plate with washers and nuts driven by a nut driver or ratchet wrench.

Place the two guide blocks on the post mount and screw the self-tapping screws to hold them in place. Drop the post sleeve over the post and top it with a post cap.