Which insulation type is known for high water resistance?

Which insulation type is known for high water resistance?

• A. Fiberglass
• B. XPS (Extruded Polystyrene)
• C. Cellulose
• D. Polyiso

Answer: (B)

Water resistance in insulation is about how well the material resists taking on moisture, because moisture can reduce its insulating value and promote problems like mold. XPS has a closed-cell structure that limits both liquid water uptake and capillary wicking, so it stays drier when exposed to damp conditions. That makes it the most effective option for high water resistance among the common insulations listed. Fiberglass can trap and hold water within its fibers and voids, and cellulose is highly moisture-absorbent due to its paper-based nature. Polyiso is also a closed-cell foam and moisture resistant, but in long-term wet exposure its performance isn’t as consistently high as XPS. So XPS stands out for staying drier and maintaining its thermal resistance in damp environments.

Water resistance in insulation is about how well the material resists taking on moisture, because moisture can reduce its insulating value and promote problems like mold. XPS has a closed-cell structure that limits both liquid water uptake and capillary wicking, so it stays drier when exposed to damp conditions. That makes it the most effective option for high water resistance among the common insulations listed. Fiberglass can trap and hold water within its fibers and voids, and cellulose is highly moisture-absorbent due to its paper-based nature. Polyiso is also a closed-cell foam and moisture resistant, but in long-term wet exposure its performance isn’t as consistently high as XPS. So XPS stands out for staying drier and maintaining its thermal resistance in damp environments.