How do you stop a fence from warping?

Choosing the right material and installing it properly will help stop a fence from warping. Poor quality materials such as wood that has not been dried prior to installation can cause boards to warp. Some fences, like the Trex fence systems, have been engineered to help them avoid warping. In the case of Trex, the pickets have curved edges which allow them to keep greater rigidity in their shape. Additionally, they interlock when they are installed thereby forcing the pickets to remain true.