# Composite decking selection: a specification checklist

Canonical: https://woodplasticcomposite.net/guides/decking-selection/
Language: en
Updated: 2026-09-24
Version: 2
Review: Specialist review not yet recorded

## Summary

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.

## 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.

https://woodplasticcomposite.net/guides/decking-selection/#section-0

## 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.

https://woodplasticcomposite.net/guides/decking-selection/#section-1

## 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.

https://woodplasticcomposite.net/guides/decking-selection/#section-2

## 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.

https://woodplasticcomposite.net/guides/decking-selection/#section-3

## Key points

Supports and span
Surface finish and conditions
Joints, ends and fixings

## Comparison

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

## Are solid boards always stronger than hollow boards?

Geometry alone is insufficient. Use profile-specific evidence for loading, supports and exposure.

## 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.

## Sources

1. Advances and challenges of wood polymer composites — https://research.fs.usda.gov/treesearch/25693