Closed-cell spray foam delivers R-6 to R-7 per inch — more than twice the thermal resistance of fibreglass batts in the same thickness. A 2-inch application on a crawlspace wall delivers R-12 to R-14. A 3-inch application delivers R-18 to R-21. For rim joists and foundation walls where thickness is limited and maximum R-value per inch is essential, spray foam's performance advantage over every other insulation product is decisive. Western Insulation explains R-value per inch for every insulation type as part of every free Langley assessment. Book at westerninsulation.ca/spray-foam-insulation/