Cromar Vent 3 BLUE Roofing Membrane – 135g

Cromar Vent 3 is a BBA-approved roofing breather membrane that covers the full range of UK pitched roof specifications. Whether you are working on a warm roof or cold roof, ventilated or non-ventilated, this single product covers the lot. For roofers who do not want to be caught out mid-job with the wrong membrane in the van, that is genuinely useful.

The Cromar Vent 3 Blue membrane is manufactured in the UK, which matters more than it might sound. British weather puts membranes through their paces — persistent wind-driven rain, freeze-thaw cycles, UV exposure during fit-out — and this product is designed with those conditions in mind rather than a warmer European climate.

Cromar Vent 3 Performance Figures

The technical numbers back up the on-site performance. At 135g per square metre, it sits in the mid-weight category — light enough to handle easily on the roof, substantial enough to do the job properly. Tensile strength is 266N in one direction and 184N in the other, with nail tear values of 167 and 253 respectively, so it holds well under fixings without tearing back. Water vapour transmission is rated at 1258, which keeps the roof build breathing as it should, and watertightness is classified W1. That is the top rating — no water penetration under standard test conditions.

The blue colouring makes it easy to identify on site and distinguishes it from standard underlays at a glance. Available in 1m x 50m and 1.5m x 50m rolls, the wider option covers ground faster on larger pitches and reduces the number of laps you need to manage. Both sizes are kept in stock at DTS for next day delivery.