Because the manufacturer’s warranty only applies if the composite installation is performed to their specification it has been reprinted here in full. Firstly, the decking boards must only have been used in normal domestic service conditions and properly fitted in accordance with recommendations including recommended joist support spacing (30 to 40 cm), expansion end gap spacing (8mm) and fixing method (T-piece and screw system). The warranty is valid for boards laid narrow groove side up only. Boards laid differently are done at your discretion and may lead to increased slippage and colour change.
Building Your Deck
Having taken delivery of your boards, we recommend you allow them a day to adjust to your local temperature and conditions before starting work. We do not recommend installing your deck in cold weather. Your WPC decking boards can be worked with normal woodworking tools. We recommend using a wood saw with a fine-tooth blade to cut boards to size. When cutting, care should be taken to ensure that boards are properly supported
Build a supporting substructure
Make sure that the area to be decked is flat and stable. Boards must not be laid directly on the ground but should be fixed to the joists of a suitable supporting substructure. This will vary, for a domestic patio deck we typically recommend a simple concrete base and our own WPC joists.
The concrete base 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.
The WPC joists should be fastened to the concrete base using screws through the joists and plastic raw plugs in the concrete base. They should be fixed so as to create parallel, regularly spaced rows in-line with the slope of the concrete base, again to allow for the run-off of water.
The maximum recommended space between joist rows depends on the angle at which you intend to lay your boards in relation to the joists. This should never exceed 40cm, please see diagram (right).
A gap of at least 15mm should be left between the ends of joists and a fixed object such as a wall. A gap of at least 8mm between the ends of joists at butt joints. These allow for proper drainage and temperature expansion.
Remember the suitable supporting substructure for your deck will vary with the circumstances
Fix boards to joists
Our WPC boards are easily fastened to the joists of a supporting substructure with the help of our stainless steel screw and plastic T-Clip system.
Start at the outside of the area to be decked. Place your first board and fix it to each joist it crosses using a row of starter clips. Then fit T-clips into the groove along the side of the board. Screw them into the supporting joists with the screws provided, one T-Clip for each supporting joist.
Fit your next board by sliding it onto the T-Clips used to secure the first board. Fitt another set of T-Clips to secure the opposite side of the board, again one T-Clip for each supporting joist. Follow a similar process to fix subsequent boards attaching the final board in a similar manner to your first.
Boards must be properly supported!
The ends of boards must be fully supported. No overhang or cantilever is allowed. At butt joints – where the ends of two decking boards meet, this may mean doubling up on supporting joists. This is because you need to ensure that each board is held in place with it’s own T-Clip where they meet.
Minimum spacing requirements
It is recommended that a gap of at least 7mm is maintained between the sides of adjacent boards. This will allow for drainage and expansion due to temperature increases. The use of plastic T-Clips helps ensure these gaps are maintained. Gaps of 8mm should be left at butt joints – where the ends of two boards meet. Gaps of 15mm should be left between the edges of boards and objects such as a wall for similar reasons.
Finish Your Deck
Having fastened your deck boards you can tidy up the sides of the deck with WPC skirting and corner trims. They can be used to hide the unfinished end of boards and supporting joists.
Our skirting trims can be screwed directly into joists with wood screws. A gap of at least 8mm should be maintained between skirting trims and the ends and sides of boards. This gap is to allow for expansion with temperature increases.
Finally, corner trims can be applied subsequent to skirting trims to achieve a finishing touch. They can be screwed directly into the joist below the decking.
However we recommend that you do not fully close your deck to allow for both air circulation and drainage.
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