Greenstop® Rigid Wall Underlay

USG Boral Greenstop® Rigid Wall Underlay is non-combustible, moisture-and mould-resistant panel that offers a 100% inorganic fibreglass facer and backer mat.

• Treated gypsum core, combined with fibreglass face and back, offers exceptional water resistance

• Scores and snaps easily for quick installation

• For use in most exterior systems as a rigid air barrier - when properly detailed by the exterior cladding manufacturer

• Meets or exceeds the requirements of ASTM C1177 for use as an exterior substrate for a weather barrier. 


Mould Resistant: High resistance to mould and mildew, scoring a 10 (highest) when tested in accordance with ASTM D3273.    

Resists Water: Glass-Mat facer on both sides sheds water.    

Fire Performance: Non-combustible gypsum core achieving a classification of Group 1-S when tested in accordance with ISO 5660 cone calorimeter test. 

Quick & Dry Installation: Quick score and snap, with neither sawing or special tools required.   

Exposure: Can be exposed to weather for up to 6 months after application.

Warranted Performance: USG Boral Greenstop® is guaranteed for 15 years against manufacturing defects and for 6 months of weather exposure after application.

Physical Properties:
  • Edge Profile SE / Square Edge
  • Nominal Sheet Sizes:
  • 10mm - 1200 x 2450/3000mm
  • 13mm - 1200 x 2750/3000mm
  • 16mm - 1200 x 3000mm
  • Weight
  • 10mm – 8.5 kg/m² (nominal)
  • 13mm – 11 kg/m² (nominal)
  • 16mm – 13.8 kg/m² (nominal)

Greenstop® is a high performance fibreglass-faced gypsum-core sheathing board for use on exterior walls when protected by an exterior face sealed or rain screen facade system.