Water absorption, swelling and Nordic exposure

State the procedure before the percentage #

Report initial conditioning, specimen dimensions, exposed edges, water temperature, duration and the calculation basis. Water absorption measures mass change, while thickness swelling measures dimensional change. They are related observations but not the same property.

Forest Products Laboratory research on fungal and moisture durability explains why moisture access remains relevant to WPC. Research on treated composites' moisture sorption likewise evaluates particular materials and treatments rather than one universal WPC value. [R46,R51]

Connect laboratory exposure to installation #

ISO 16616 addresses test methods for exterior NFC deck boards. Its scope is a useful starting point when organizing evidence, but the exact procedure and product requirements still need to be identified.

For a Nordic project, review water exposure, freezing conditions, support details and the ability to inspect the installation. A short test can support a defined comparison; it does not alone establish a decades-long lifetime in every climate.

[3]

A buyer's evidence request #

Ask for the complete report or a clearly identified summary containing the test method, specimen identity and results. Request conditioned mechanical performance when that is relevant to the intended use. Make sure a capped sample represents the cut ends and installation details that will exist on site.

Finally, keep marketing language measurable. Moisture-resistant is not the same as impermeable. A good specification explains which exposures were assessed and what installation practice is needed to maintain the intended performance.

Evidence and source scope #

[1] Official research synthesis; FPL-GTR-303.

[2] Experimental study.

[3] Official standards scope; no reproduction of paid normative text.

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