PIR 20mm, 30mm or 40mm? Short answer: pick the thinnest board that reaches your target Rd within the available build-up. We stock 20, 30 and 40 mm PIR at about 0.60 × 1.20 m.
When 20 mm?
Renovations with little space — floor, lining wall, roof detail.
When 30 or 40 mm?
More insulation per board when the structure allows it. 40 mm is the thicker standard when height allows.
PIR or stone/glass wool?
PIR wins on heat per millimetre. Mineral wool wins on sound. Shop: insulation. Positioning: buy insulation.
FAQ
Is 20 mm PIR enough?
Often yes for top-up insulation or tight spaces; for new-build targets you usually need more thickness or layers.