Can I attach Trex pickets to steel posts?

Trex rails and pickets can be combined with steel posts as long as the right fasteners are used. In fact, we offer our Horizons fence system with iron (galvanized steel, black powder-coated) posts as an option instead of our composite posts. Please note that the 25-year residential / 10-year commercial warranties only apply to manufacturing defects as applicable to Trex composite materials. Warranties on third-party metal posts, if any, would not be included with the Trex warranty.