Breather Membranes-FAQ
Breather membranes are one of the most important, and often misunderstood, components in a pitched roof build. Whether you're a roofer working on a new build, a builder tackling a full re-roof, or a homeowner trying to make sense of what is going in above your head, this page covers the questions we get asked most.
Did you know?
Don & Low's Roofshield, one of the breather membranes available from Roofbase, has been used in extreme climates including the Antarctic, proving its reliability in some of the most extreme weather conditions on earth.
Click on a question to reveal the answer
A. A breather membrane is a water-resistant material installed beneath the tiles or slates on a pitched roof.
It acts as a secondary barrier against wind, rain, and snow, while at the same time allowing moisture vapour from inside the building to escape outwards. This dual function, keeping liquid water out while letting water vapour through, is what makes it "breathable." Without it, trapped moisture can cause condensation, mould, insulation deterioration, and timber rot.
A. Moisture is constantly generated inside a building through everyday activities like cooking, showering, and heating. That moisture vapour rises and, without a proper membrane, becomes trapped in the roof space where it condenses on cold surfaces.
Over time, this can lead to damp insulation, which loses its thermal effectiveness, mould growth, and decay of structural timbers. A breather membrane allows that vapour to escape naturally while preventing any rain or wind-driven moisture from getting in.
A. These two products are often confused, but they do different jobs.
A breather membrane is installed on the outer side of the insulation, beneath the tiles or slates. It lets moisture vapour escape from the roof space to the outside, while repelling water.
A vapour control layer (VCL) is installed on the inner side of the insulation, and its job is to reduce the amount of moisture vapour entering the roof structure from inside the building.
A. Most breather membranes can reduce, but not entirely eliminate, the need for traditional ventilation in many roof configurations. However, Roofshield®’s patented Spunbond Meltblown Spunbond (SMS) structure ensures high airflow levels while facilitating moisture vapour transport, drastically reducing the risk of interstitial condensation. Unlike conventional membranes that depend on airtight VP film layers, Roofshield® offers a breathable, efficient solution that eliminates the need for additional ventilation products.
We would advise to aways check the manufacturer's third-party accreditation and follow the guidance in BS 5250 for your specific roof type.
A. Breather membranes in the UK must comply with BS 5250 (moisture management) and BS 5534 (pitched roof wind loading), ensuring a vapor-permeable structure (sd ≤ 0.12 m) that allows moisture escape.
A. Yes. Roofbase offer delivery to areas surrounding each of their branches. If you need breather membranes delivered to site, contact your local Roofbase branch directly and they will be able to confirm delivery availability for your area and arrange what you need.
A. Absolutely. The teams at all Roofbase branches are knowledgeable across the full range of pitched roofing products they stock, including breather membranes. Pop into your nearest branch or give them a call.
A. Roofbase holds extensive stocks of leading breather membrane brands, including Breatheshield from Garde Roofing Supplies and Roofshield from Don & Low.
Speak to your local Roofbase branch for availability and to discuss which product is right for your project.
