The correct crawlspace insulation system for Langley BC combines two components — and omitting either one leaves the job incomplete. Closed-cell spray foam on crawlspace walls provides R-20 or above while simultaneously acting as air barrier and vapour barrier. A heavy-duty 10 to 20 mil polyethylene vapour barrier across the crawlspace floor blocks ground moisture from evaporating upward into the space above. BC Building Code requires vapour barriers in crawlspaces — this is not optional. Western Insulation installs both as a coordinated system on every Langley crawlspace project. Book at westerninsulation.ca/basement-and-crawlspace-insulation/