Structural Plastics

Deck Board and Guardrail Testing

Wood-plastic composites (WPCs) are produced by thoroughly mixing ground wood particles and heated thermoplastic resin. The most widespread use of WPCs in North America is in outdoor deck floors, but they’re also used for handrail and guardrail systems, stairs, fences, landscaping timbers, cladding and siding, park benches, molding and trim, window and door frames, and indoor furniture. Like any other building product, they may need to have their code compliance verified.

According to the International Residential Code (IRC), Chapter 3 Building Planning, Section R317 Protection of Wood and Wood-Based Products Against Decay, Subsection R317.4 Wood/Plastic Composites, “Wood/plastic composites used in exterior deck boards, stair treads, handrails and guardrail systems shall bear a label indicating the required performance levels and demonstrating compliance with the provisions of ASTM D7032.” NTA can permit labeling of your product as part of a certification program that will verify the code compliance of your product.

What NTA can do

NTA is accredited by A2LA under ISO/IEC 17025 to test, ISO/IEC 17020 to inspect, and the code compliance of structural plastics for manufactured homes and modular factory-built construction and structural composite wood-based products for building materials.

In 2008, NTA was one of the first accredited testing laboratories that could run the ICC-ES requirements for composite deck boards. We conduct tests per ASTM D7032, standard specification for establishing performance ratings for wood-plastic composite deck boards and guardrail systems (guards or handrails), and ASTM D7031, standard guide for evaluating mechanical and physical properties of wood-plastic composite products. NTA is also able to perform testing per ICC-ES AC 174.

WPCs are evaluated through:

  • Flexural tests
  • Temperature and moisture effects
  • Accelerated weathering/ultraviolet (UV) resistance test
  • Freeze-thaw resistance test
  • Biodeterioration tests, including termite and fungus decay resistance
  • Fire performance

Deck boards are additionally evaluated through:

  • Creep-recovery
  • Duration of load, or creep rupture
  • Determination of unadjusted allowable load
  • Mechanical fastener testing and uplift resistances
  • Slip resistance (i.g. ASTM F1679)

Guards and handrails are additionally evaluated through:

  • Concentrated and uniform load tests
  • One- and two-family dwelling requirements

For more information about our structural plastic testing services, contact us.

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