Roofing underlays

LETO 125

LETO 125 is a BBA-certified, vapour-permeable roofing underlay designed for modern pitched roof construction. Manufactured from a durable three-layer polypropylene construction, it provides dependable weather protection, excellent breathability and W1 water resistance, helping to reduce the risk of condensation while protecting the roof structure from external moisture. Suitable for warm and cold roof applications, LETO 125 combines straightforward installation, reliable performance and excellent value for everyday roofing projects.

 

Solar
Compatible
Vapour
Permeable
W1 Resistance to
Water Penetration
Resists Wind
Uplift
UV Stable
3 Months
UK wind zones map

Wind Zones

Taped laps 1-5
BATTENED LAPs 1-2
BBA CE UKCA

Technical Specifications

Weight, gsm 125
Resistance to water penetration, Class W1
Water vapour transmission (Sd), m 0.02
Tensile strength (MD/CD), N/50mm 280 / 155
Elongation at max. tensile force (MD/CD), % 70 / 60
Nail tear resistance (MD/CD), N/50mm ≥50 / ≥50
Flexibility at low temperature -40°C
UV stability, Months 3
Reaction to fire, Class E
Colour Blue

Ideal For

  • Warm roof construction
  • Cold roof construction
  • Vented and unvented roof systems
  • Timber frame and rafter roofs

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Documents & Downloads

BBA Ceritficate - For use in cold non-ventilated pitched roof systems

BBA Ceritficate - For use in warm roof and cold ventilated pitched roof systems