Breathable roofing membrane is an underlay, not the finished roof covering
Breathable roof membrane sits beneath tiles or slates as a secondary layer in a pitched-roof build-up. It is different from shed roofing felt, which can form the exposed covering on suitable garden buildings, and from EPDM rubber roofing used as a finished flat-roof membrane.
Choose 1m or 1.5m × 50m rolls
The same 135gsm membrane is available in two roll widths. The 1m roll is easier to handle in tighter working areas; the 1.5m roll covers more roof width per run and can reduce the number of horizontal laps.
Breathable does not automatically mean no ventilation
The required ventilation depends on the complete roof build-up. NHBC guidance distinguishes low-resistance and high-resistance underlays and also changes the ventilation treatment where a low-resistance underlay is fully supported on high-resistance sarking such as OSB or plywood. Follow the roof design and the membrane manufacturer's installation instructions.
Use graded roofing battens where the roof specification requires them
After the underlay, use the batten specified for the roof covering. Browse our Roofing Battens range for BS 5534 graded batten.
Need help understanding roof underlay?
Read What Is Breathable Roofing Membrane? for the difference between breathable roof underlay, vapour control layers and finished waterproof roof coverings.
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