PIR 20mm, 30mm or 40mm? The short answer is this: pick the thinnest insulation board that reaches your target Rd within the available build-up.
We stock 20, 30 and 40 mm PIR insulation boards. Standard size is about 0,60 by 1,20 metre.
When is 20 mm the better thickness?
Choose 20 mm on renovations with little available space. Typical spots are a floor, a lining wall, or a tight roof detail.
When do you choose 30 mm or 40 mm?
Choose 30 or 40 mm when the structure allows a thicker insulation board. You then get more insulation per board. 40 mm is the thicker standard thickness when the available height allows it.
PIR versus mineral wool or glass wool
PIR wins on heat insulation per millimetre of thickness. Mineral wool and glass wool win on sound. Shop here: insulation. Positioning advice: buy insulation.
FAQ
Is 20 mm PIR enough?
Often yes for top-up insulation or very tight spaces. For new-build targets you usually need more thickness or extra layers.