Cromar Vent 3 CLASSIC Roofing Membrane – 115g

The Cromar Vent 3 Classic roofing membrane sits in that sweet spot — not the lightest option on the market, not the heaviest, but a genuinely capable mid-weight breather membrane that ticks the right boxes for most pitched roof applications. It carries BBA approval for use in warm and cold roofs, ventilated and non-ventilated, which means it covers the vast majority of residential and light commercial roof builds without any fuss over specification compliance.

At 115g/m², this membrane has the substance to handle site conditions without tearing on installation, while staying light enough to work with comfortably on the roof. The nail tear strength figures — 99 cross-direction and 110 machine-direction — reflect a membrane that holds up around fixings rather than creeping or splitting back from the batten line over time. Water vapour transmission sits at 1258, and vapour resistance at a very low 0.16, so it breathes freely. That matters in both cold and warm roof constructions where trapped moisture causes long-term problems with insulation and timber.

Where the Cromar Vent 3 Classic Gets Used

This membrane is a standard choice for new-build and re-roofing work under slates, plain tiles, concrete interlocking tiles, and most other pitched roof coverings. The BBA certificate covers both ventilated and non-ventilated roof designs, which gives roofers and specifiers the flexibility to use one membrane across a range of jobs rather than stocking multiple products.

UK Manufactured for UK Weather

Cromar manufacture the Vent 3 Classic in the UK, and that is not a trivial point. A membrane designed and tested against British weather conditions — driving rain, freeze-thaw cycles, extended wet periods — performs differently from one engineered to a different climate. The W1 watertightness classification confirms it meets the required standard for temporary weather protection during construction, which matters if the roof covering goes on over several days or gets delayed.

Available from DTS in 1m x 50m and 1.5m x 50m rolls, with bulk quantities available for larger projects. The 1.5m width reduces the number of laps on wider rafter spans, which speeds up laying and keeps material waste down.