At a glance
Select composite decking as an installed system: boards, supports, fasteners, drainage and movement allowances. Ask for evidence for the exact profile, surface and intended use. A generic WPC label is not a span, slip or service-life rating.
Key points
- Supports and span
- Surface finish and conditions
- Joints, ends and fixings
Define the use before the board #
Describe the project: private terrace or public walkway, shaded or exposed, frequently wet or usually dry. Record anticipated loading, access for maintenance and the supporting structure. This brief gives suppliers something concrete to respond to.
Compare complete systems #
Request the exact profile, fasteners, supporting structure and installation instructions. Ask for permitted spans and loading for the intended use. Do not carry a spacing rule from one product to another, or assume a thicker board automatically permits a longer span.
Read the evidence in context #
For a wet area, ask for relevant slip-test evidence and the test conditions. Check how the surface was prepared and whether the result applies to the finish you are buying. For exposed locations, ask about dimensional movement and weathering evidence.
Plan for life after installation #
Get written cleaning instructions, replacement arrangements and warranty exclusions. Include drainage, access and movement allowances in the project review. Compare total installed scope so that missing accessories or preparatory work do not distort the price comparison.
Practical comparison checklist
| Topic | Evidence or meaning | What to check |
|---|---|---|
| Loading | Profile-specific evidence | Supports and span |
| Wet surfaces | Slip-test report | Surface finish and conditions |
| Movement | Installation instructions | Joints, ends and fixings |
| Maintenance | Cleaning instructions | Access and responsibility |
Common questions
Are solid boards always stronger than hollow boards?
Geometry alone is insufficient. Use profile-specific evidence for loading, supports and exposure.
Question permalink ↗Can every composite board span 600 mm?
No universal spacing follows from the material name. Use the permitted spacing for the exact product and project.
Question permalink ↗Sources & further reading
- Advances and challenges of wood polymer composites ↗USDA Forest Products Laboratory · Research publication · 2026-09-24
Cite this page
J. A. Gill. “Composite decking selection: a specification checklist” Version 2. Updated 2026-09-24. https://woodplasticcomposite.net/guides/decking-selection/
Author profile
Author: J. A. Gill
WPC and natural-fibre composite specialist · Innovator, inventor, product designer and entrepreneur
Expanded reference format with a direct summary, comparison checklist and source links.
General material information is not product certification or project-specific engineering advice.
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