Here at Cladco Profiles, we have a wide range of options to suit your Composite Decking project. From Composite Joists designed for a concrete base, to structural composite joists which can be used on a concrete or grass base. These can be raised to Timber Joists which can be used on a variety of foundations, raised or flat.

To start your decking frame with timber - Prepare a level, weed-free area for the decking frame. Clear away any plants, weeds, rocks, or other materials that might be obstructing your site.


To create a framework, cut the 100mm x 47mm tanalised timber to the required lengths for each section of the framework, then join using exterior wood screws. Check the frame is to the desired proportions. The maximum recommended space between joist rows depends on the angle at which you intend to lay your boards in relation to the joists, but should never exceed 40cm.


To raise the timber frame, cut four blocks of tanalised timber to the desired height. Screw these to the inside of the frame at each corner, ensuring they’re flush with the top. Use at least three screws per block, as these legs will be taking all the weight

If your deck will be sitting on grass or soil, you’ll need to place a solid block or slab underneath the edge leg to spread the load and provide a level, stable base. Check the frame is level with your spirit level to avoid any sloping surfaces.

For Composite Joists, prepare a concrete base. This should be at least 10cm thick and have a slight slope – we suggest a gradient of 1 in 80 – that runs away from the property to allow for the run-off of water that collects under the deck.


As above Joists should never exceed 40cm distance apart.


A gap of at least 15mm should be left between the ends of joists and a fixed object such as a wall and of at least 8mm between the ends of joists at butt joints. These allow for proper drainage and temperature expansion.


Once you have either your timber frame or composite frame in place, it’s now time to lay Cladco Composite Decking Boards.

For more information on installing composite decking please see our Installation Guide.


Have any questions or would like further information? Call our friendly sales team on 01837 659901 or visit our Website.