Cromar Vent 3 Light is a triple-layer breathable roofing membrane made from spun-bonded polypropylene with a micro-porous film core. At 95gsm it delivers solid waterproofing, excellent vapour permeability and UV stability for up to three months exposure.
Size
QTY
Price
QTY
1.5m x 50m
54
£1,620.00£1,944.00
1m x 50m
1
£24.95£29.94
1m x 50m
54
£1,188.00£1,425.60
1.5m x 50m
1
£36.95£44.34
The Cromar Vent 3 Light roofing membrane is a 95gsm breather membrane built from three layers of spun-bonded polypropylene around a micro-porous polypropylene film. That construction is what makes it work: the outer layers handle the mechanical abuse of installation and everyday weather, while the film core lets water vapour out without letting liquid water in. Clean in concept, clean on the roof.
Available in 1m x 50m and 1.5m x 50m rolls, this membrane is sized for practical site use. Whether you’re working alone across a standard pitch or cutting runs for a more complex layout, the widths suit the job without excessive lapping waste. At 95gsm the Cromar Vent 3 Light sits in the lighter end of the breathable membrane range, which means it handles well in wind and is straightforward to cut and staple without a fight.
Where Cromar Vent 3 Light Performs
This membrane is suitable for both warm and cold roof applications, which covers a large proportion of the residential and light commercial roofing market. On a cold roof it allows moisture to escape from the insulated void rather than building up over time. On a warm roof build-up it contributes to the overall vapour management strategy above the structural deck.
Tear resistance and tensile strength are genuinely worth mentioning here because site conditions are not a laboratory. Membranes get walked on, caught by wind, and occasionally mistreated before the tiles go on. A membrane that tears at the first snag wastes time and materials. The Cromar Vent 3 Light holds together well enough to get through a standard installation without drama.
UV stability for up to three months gives you a reasonable working window between membrane installation and covering. That is not an invitation to leave it exposed indefinitely, but it does mean a few weeks of wet weather or scheduling delays will not immediately compromise the product. For most roofing projects that is more than enough buffer to work with.
Pro Tip: Always lap the membrane so the upper sheet overlaps the lower one by at least 150mm, and tape all horizontal laps with a compatible self-adhesive membrane tape to prevent wind-driven rain getting under the overlap.
The Cromar Vent 3 Light is used on pitched roofs in new build and refurbishment work. Roofers use it under tiles, slates, and metal roof coverings where a breathable underlay is required to manage vapour transmission through the roof build-up. It suits both cold and warm roof constructions across domestic housing, extensions, and light commercial buildings.
Installers also use it on outbuildings, garages, and agricultural structures where a reliable, cost-effective breather membrane is needed without the weight or bulk of a heavier specification product.
Best For
Pitched roof installations under tiles or slates
Cold and warm roof applications
New build and refurbishment roofing
Domestic housing and extensions
Light commercial and agricultural buildings
Compatible With
Concrete and clay roof tiles
Natural and artificial slates
Metal roof coverings
Timber rafter and batten systems
Standard roofing battens and staple fixings
Key Properties
95gsm weight
Triple-layer spun-bonded polypropylene construction
Micro-porous film core for vapour permeability
Waterproof outer layers
UV stable up to 3 months exposure
High tear and tensile strength
Available as 1m x 50m or 1.5m x 50m rolls
Not suitable for: Not suitable for flat roof applications where a fully bonded waterproofing system is required. Not intended for permanent exposure without a covering roof finish.
Lay the membrane horizontally across the rafters starting from the eaves and working up towards the ridge. Keep it taut but not stretched tight, as a small amount of drape between rafters helps shed any water that gets under the tiles. Fix with clout nails or staples through the rafter line, then batten immediately over the top to secure it properly.
Lap each successive course over the one below by a minimum of 150mm. On exposed sites or where wind-driven rain is a concern, tape horizontal laps with a compatible self-adhesive flashing or membrane tape. At verges and abutments, fold the membrane up and tape to the adjacent surface before fitting any cover flashings.
Start at the eaves and unroll horizontally across the rafters, allowing a slight drape of around 10mm between supports
Fix to the top of each rafter using clout nails or a membrane stapler, keeping the membrane flat and wrinkle-free
Fit roofing battens immediately over the fixed membrane to provide a secure mechanical fixing
Roll the next course up the slope, lapping it a minimum of 150mm over the course below
Tape all horizontal laps with a compatible self-adhesive tape, particularly on exposed sites
At verge edges, fold the membrane over the barge rafter and fix securely before applying the verge finish
At any abutments or penetrations, turn the membrane up and tape to the adjacent surface, then cover with appropriate flashing
Is the Cromar Vent 3 Light suitable for cold roof construction?
Yes, it is suitable for both cold and warm roof applications. On a cold roof it allows moisture vapour to escape from the insulated void rather than accumulating over time, which is the primary function of a breathable underlay in that type of build-up.
How long can the membrane be left exposed before the tiles or slates go on?
The Cromar Vent 3 Light has UV stability for up to three months. That gives a reasonable working window for most projects, but you should still aim to get the roof covered as soon as practically possible. Three months is a buffer, not a target.
What minimum lap should I use between courses?
A minimum 150mm horizontal lap is recommended between courses. On exposed or high-pitched roofs, tape those laps with a compatible self-adhesive membrane tape to prevent wind-driven rain finding its way under the overlap.
The Cromar Vent 3 Light is a triple-layer breather membrane comprising two outer layers of high-tensile spun-bonded polypropylene thermally bonded around a micro-porous polypropylene film core. The micro-porous film provides the vapour-permeable, waterproof barrier that is central to its performance. At 95gsm it meets the requirements for a Class 1 vapour-permeable underlay under BS 5534 and is suitable for pitched roof applications with rafter spans and batten spacings within standard guidelines.
Weight
95gsm
Construction
Triple-layer spun-bonded polypropylene with micro-porous film core
Available Sizes
1m x 50m, 1.5m x 50m
UV Stability
3 months exposure
Application
Warm and cold pitched roof construction
Standard
Class 1 vapour-permeable underlay
SKU
Vent3Class-1
Size
1.5m x 50m, 1m x 50m
Box Quantity
1, 20, 25, 54
Reviews
There are no reviews yet.
Be the first to review “Cromar Vent 3 LIGHT Roofing Membrane – 95gsm”Cancel Reply
Reviews
There are no reviews yet.