Cromar Vent 3 Classic: 50m x 1m
Cromar Vent 3 Classic Breather Membrane
The Cromer Vent 3 Classic membrane is a triple-layer fabric, high-performance membrane. It is layers of spun-bonded polypropylene around a micro-porous polypropylene film. This roll is 50m x 1m and covers 50m ²
It is a highly vapour permeable, and waterproof membrane that is designed for use in either a fully supported or unsupported tile, slate or metal roofing system It has high tensile strength and great wind uplift resistance and conforms to a number of standards including BS 5534:2018 and BS 5250.
| Specification | Value |
| Weight, g/m ² | 115 |
| Tensile Strength |
MD 195N/50mm TD 130N/50mm |
| Elongation |
MD 51% TD 65% |
| Nail Tear |
MD 99N TD110N |
| Hydrostatic Head | 281cm |
| Reaction to Fire | Class E |
| Resistance to Streaming Water | Pass |
| Resistance to Water Penetration | W1 |
| Water Vapour Resistance (Sd)(m) | 0.02 |
| UV Resistance | 3 Months |
The outer layer of the membrane acts as a functional waterproof surface, the middle is the breathable waterproof membrane with the inner layer protecting the membrane from damage. It is ideal to use draper over rafters or to laid over insulation.
The membrane is laid horizontally from the eaves with the logo on the outermost working up the roof.
Minimum Horizontal Laps
| Roof Pitch | Min Horizontal Lap Partially Supported (mm) | Min Horizontal Lap Fully Supported (mm) | Min Horizontal Lap (mm) |
| 12.5 ° - 15 ° | 225 | 150 | 100 |
| 15 ° + | 150 | 100 | 100 |
Cromar is suitable for use across wind zones 1-5 depending on the roof's batten gauge.
Windzone Chart
| Batten Gauge | 345 mm | 245 mm | 345mm (Taped Laps) | 345 mm (Integral Tape) |
| Vent 3 Classic | Zones 1-2 | All Zones | All Zones | All Zones |
