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Protect A1 T3 Plus underlay

Protect A1 T3 Plus is a high performance, heavy-duty type HR roofing underlay designed for all cold and warm pitched roofs, developed to overcome the disadvantages of traditional Type 1F, 5U felts and plastic sheet materials and is used in conjunction with high and low level ventilation.

A new and improved fourth generation of the original A1T3 product, Protect A1 T3 Plus provides a class leading product weight of 190gsm, offering a robust secondary line of defence to the roof, whilst offering customers added value for money.

Features & benefits

  • Completely air and water tight, achieving >2.0m hydrostatic head of water resistance.
  • Regularly used for new build and re-roofing schemes.
  • Good nail tear strength and tensile strength.
  • Has unrestricted wind uplift resistance across the UK and Ireland – Zones 1-5 at 345mm batten gauge, without the need for additional sealing tapes.
  • UV and heat resistant.
  • Absorbent undersurface prevents condensate drip-off.
  • Easy to cut and handle, saving time on installation over traditional felts.
  • Does not generate nuisance noise under wind loading.
  • Resistance to wind pressure – 2094Pa, tested to BS 5534.
  • UKCA and CE marked.

Glidevale Protect has created two handy visual guides to help you choose the correct ventilation strategy for your projects. Click below to view…

Roof Covering ‘Impermeable’ – Ventilation guidance according to BS5250

Roof Covering ‘Permeable’ – Ventilation guidance according to BS5250



Range Brochure


Product Brochure


Specification clause


Fixing instruction


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For any questions or queries about our product ranges and the technical support services we can offer, please contact us using the form below.

Glidevale Protect is a division of Building Product Design Ltd.

Other subsidiaries include ventilation systems specialist Passivent and Kingfisher Louvres, manufacturer of aluminium louvres systems.

Important Notice

Please be vigilant of fraud/cyber crime. If you receive an email from our parent company Building Product Design Ltd, please check that the email address from the sender ends in '' and any phone number given is 0161 905 5700.

If you receive any emails ending in '' or '', these are NOT legitimate, and you should contact us as soon as possible at

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