Don & Low designed the MultiTX® range of underlays with moisture transfer in mind to mitigate the risk of condensation within the roof structure and ensure optimal protection against the elements. Notably, the MultiTX® range includes products that have obtained Agrement certification from BBA in the UK, affirming their suitability for warm non-ventilated, cold ventilated and non-ventilated pitched roof systems and walling. Additionally, MultiTX® Plus has received NSAI approval in Ireland.

The MultiTX® range of products is well-suited for various roofing applications, including fully supported or unsupported cold and warm systems. The comprehensive range comprises four distinct products, each differing in weight and construction, catering to diverse roofing underlay and walling membrane requirements.

Key benefits

  • The modern alternative to traditional bituminous-based (type 1F) roofing felts
  • Lightweight fabric minimises manual handling issues
  • Excellent low-temperature flexibility
  • Resistant to water penetration and stabilised against UV degradation

Additionally, the MultiTX Solar, when used with close-fitting PV panels

  • Removes the need for a ventilated counter batten space
  • Helps to comply with Building Regulations Part L, Future Homes Standards & NHBC
  • Resistant to water penetration and stabilised against UV degradation
  • It helps to meet BS 5250 Ventilation requirements when used with High and Low-Level Ventilation.


MultiTX® Plus

MultiTX® Pro

MultiTX® Maxi

MultiTX® Solar


Vapour permeable, air barrier HR roofing underlay and breather membrane for walling and roofing

Weight (g/m2)






3-layer laminate

CE Compliant

BBA Certified


IAB Certified





Protects against wind driven rain, snow and dust
Exceptional resistance to water penetration
Stabilised against UV degradation
MultiTX Plus Roll Insert English Download
MultiTX Pro Roll Insert English Download
MultiTX Maxi Roll Insert English Download
MultiTX Solar Roll Insert English Download
MultiTX Plus Datasheet English Download
MultiTX Pro Datasheet English Download
MultiTX Maxi Datasheet English Download
MultiTX Solar Datasheet English Download
NSAI MultiTX® Plus Certification -Barrier roof tile underlay English Download
BBA MultiTX® Barrier Undelays Certificate English Download