There are crucial differences between the non-breathable and breathable membranes used for new roof installation.

Both membrane systems are designed to prevent water ingress on a pitched roof while reducing the chances of damp build up. As the name suggests, the main difference between non-breathable and breathable membranes is to do with the ability to breath for ventilation of the building.

Breathable membranes let a building breathe by allowing the moisture within the building to pass through the membrane and out of the building. Non-breathable membranes are not air permeable and do lot allow the moisture within the air to pass through them.

So which is best?

It is not so much which is best but which suits your property type. Both are modern underlay materials that are the ideal new solution for roofing underlay as an alternative to older underlay materials. Breathable membranes are newer and have become a popular choice with many roofers because it can be used on newer build properties alongside eave vents and ridge vents. But with breathable membranes, there has to be adequate ‘air gap’ between the underlay and the roofing slate or tiles to ensure that the moisture passing through has somewhere to go. Otherwise the moisture that passes through the membrane can then cause rot and damp build up on the roofing frame.

Non-breathable membranes are better at retaining heat in the property by reducing heat loss through the roof though the lack of breathability means that they should only be fitted as part of a cold ventilated pitched roof systems. Roofing needs to breathe and any opportunity to maximise ventilation in the roof area of a property is always a benefit. Warm roofing areas (that receive more direct sunlight) or properties that are lacking in sufficient ventilation should use breathable membrane underlays.

Find out more

Different properties need different types of underlay. We can advise you on the differences during a site visit to quote you for a new roof cost.

At Balmore, we are one of the leading local roofing contractors in Scotland with nearly 40 years of service across the central belt of Scotland.

From our head office in Glasgow, we can provide the complete roofing and building maintenance service ranging from traditional roofing repairs to new slate or tile roof fitting and emergency roofing work after storm damage.

Roofing Services

To discuss your specific roofing needs, to find out more about the range of roofing services that we offer or to request specific case studies of work we have done, please call our head office in Glasgow on 0141 944 6100 or email