Composite decking from China: installer checks
Before ordering, have your installer approve the exact board profile, support layout, expansion details and fixing system. Agree wet slip evidence, ask a competent adviser about fire performance for the location, and resolve local planning questions. Factory documents can be coordinated by Cambridge China Bridge.
Approve spans for the exact board
Obtain the installation manual and structural evidence for the proposed board profile, material composition, thickness and surface finish. Have your installer record the accepted support spacing, board orientation, end support and permitted overhang. Ask whether diagonal laying, steps or concentrated loads need a different layout. Do not transfer span advice from another board that looks similar.
Identify furniture, heavy planters and any proposed hot tub before approval. Ask the installer whether a structural designer should assess these loads and whether they need independent support. Put the approved board identity and layout into your product specification, with unresolved items clearly marked.
Approve the subframe separately
Ask for a site drawing showing foundations or pads, beams, joists, bracing and connections. Distinguish the board's span between joists from the joists' span between supports. Have the installer confirm ground suitability, frame stability, drainage, ventilation and access for maintenance.
If the factory supplies composite support battens, ask whether they are structural members or only suitable over continuous support. Confirm the suitability of timber treatment or metal corrosion protection, including connections between different materials. Check board joints, perimeter edges and steps have the support and fixing access the chosen system needs.
Agree expansion gaps and fixings together
Require a gap schedule based on the manufacturer's instructions for the actual board lengths and installation temperature. Cover side gaps, end joints, walls, posts and other fixed obstructions. Ask how the boards move, where movement is restrained, and how fascia boards and trims avoid trapping them. Do not accept a generic gap copied from another product.
Approve the exact clips, screws, starter fixings and any face-fixing details for the selected board and subframe. Record screw material, engagement, pilot-hole instructions and tightening method. Have the installer assemble a sample joint to check fit and movement. Agree that changes to the board groove, clip or screw need renewed approval before production.
Request wet slip evidence
Ask for wet pendulum test results for the exact walking face, with the test method, slider, surface condition and test directions identified. HSE notes that profiled floors may need testing in different directions. Have a competent test specialist interpret the results for the proposed use, including footwear or barefoot use where relevant.
A dry result or an unexplained 'anti-slip' label does not answer your wet-use question. Ask how wear, cleaning and surface contamination will be managed, and agree drainage and an algae-removal routine with the installer. Our test report verification guide explains how to check report identity and scope.
Define the fire evidence the location needs
Show a competent adviser the deck's position relative to the house, boundaries, escape routes and any balcony or roof terrace. For an England project, ask them to identify the applicable building fire safety guidance and whether it calls for particular performance evidence. Agree the requirement before selecting the board.
Request the relevant fire test and classification reports, identifying the board composition, thickness, mounting, substrate and scope of use. Ask the adviser to distinguish reaction to fire from fire resistance and confirm what the report establishes for your installation. Do not approve an unexplained 'fireproof' claim. Use our construction materials guide for the separate product-documentation checks.
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Close planning questions before releasing the order
England's householder guidance defines a raised platform as more than 0.3 metres high. Ask the local planning authority or your planning adviser to review the proposed deck height, area, position and existing ground levels, especially on a sloping site. Have them check the complete proposal and local restrictions rather than treating height alone as approval. Elsewhere in the UK, start with the relevant national guidance and local authority.
Our garden permissions guide covers the wider planning and building-control review. Before authorising production, retain the installer-approved drawings, installation manual, fixing schedule, accepted reports and site decisions under matching revisions. Cambridge China Bridge's own staff in China can obtain the factory documents and track changes; your local advisers assess suitability for the site.
Frequently asked questions
What joist spacing should composite decking use?
Use the spacing approved for the exact board, laying direction and loads. Have your installer confirm it from the manufacturer's instructions and supporting evidence, including joints, steps and overhangs.
What expansion gaps does composite decking need?
Ask for a manufacturer-based gap schedule covering board lengths, installation temperature, end joints and fixed obstructions. Approve the gaps and fixing system together so the boards can move as intended.
How do I check composite decking is safe when wet?
Request wet pendulum results for the exact surface, with test directions and conditions identified. Have a competent specialist interpret them for the intended use, and agree drainage and cleaning.
Do I need planning permission for garden decking?
Ask your local planning authority to assess the exact height, area, position and site restrictions. England's householder guidance is not a blanket approval for every deck. Resolve the permission route before ordering.