Install a structurally sound sub-frame for your decking with our durable and hard-wearing Composite Joists. Expertly designed with a hollow, lightweight composition, our Joists are weather-resistant, which means they will not rot, warp, or rust. Requiring no treatment or replacement, these Composite Joists are low maintenance providing you with that much needed peace of mind. We recommend that the joists are spaced 30cm apart in installation, with an added 10cm expansion gap when fitting adjacent to a wall or fence.