How do I fix warping boards on my gate?

It is not uncommon for any gate, regardless of material, to require some attention as it ages. This is true of Trex as well. Sometimes, expansion and contraction due to temperature and humidity changes can occur and the boards on the gate may warp the bottom fascia board or the uprights on the edges of the gate. This can be improved by using screws to create additional contact points to flatten the boards. 

Trex does not manufacture gate-specific parts so pickets are adapted to make the necessary components to create a finished look. The adaptations are designed to take the best advantage of the Trex material to make a gate that closely matches the look of the fence. You may notice that the bottom piece requires notching and ripping the material to get it as close to flush with the uprights as possible. Taking off the curled edge of a picket creates a piece flat enough to use as fascia. The compromise is that the thin material is more likely to flex.

If the fascia or uprights are warping, attach fasteners at the edge of the pickets so they go through the most material. If possible, it would be best to clamp the rail or upright first, then add screws. Use a #7x1-5/8" Square Drive Trimhead Screw. These screws have very small heads but if you want to reduce their visibility, dab a small amount of paint on the head. This may not be necessary if you sink the head just below the surface. The material that is displaced by the screw can be pinched together and tapped lightly with a hammer to cover up the screw head and flatten the area where the screw was attached.