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Belzona 3111 (Flexible Membrane)

Belzona 3111 (Flexible Membrane)

A single-component, liquid-applied roof coating for long-term roof protection and waterproofing. 

A cold-applied liquid coating for long-term roof protection, providing outstanding waterproofing and weatherproofing properties. This single-component, solvent-free roof coating will bond strongly to all types of roofing materials, following even complex roof contours, and will allow the surface to breathe due to its microporous structure. The applied system incorporates a reinforcement sheet to allow an easy control of the coating thickness during the application as well as adapting to roof movement due to its outstanding elasticity.

This water-based material can be applied on almost any location including schools, hospitals and public buildings thanks to its low odour. It is certified by the BBA and has proven to provide excellent protection of roofs for in excess of 25 years.

Key benefits: 

  • Provides long-term roof protection
  • Microporous structure allows trapped moisture to escape whilst providing long-term weatherproofing protection
  • Reduced health and safety risks as it is solvent-free
  • Lightweight material, will not overload existing structures
  • Excellent adhesion to a wide range of materials including felt, asphalt, lead, zinc, copper, glass, concrete and brick
  • Adapts to roof movements due to its outstanding elasticity
  • Can be easily applied by brush and roller with no mixing required
  • Application and cure at room temperature no hot work involved
  • Energy Star approved as it incorporates special reflective fillers, which reflect sunlight and minimize air conditioning costs

Applications for Belzona 3111 (Flexible Membrane) include:

  • Creation of waterproof and weatherproof roof surfaces
  • Long-term roof leak repair and protection of deteriorated gutters
  • Sealing of glazing bars
  • Weatherproofing around upstands and other roof protrusions such as skylights, chimneys and vents
  • Replacement of damaged or missing flashings
  • Sealing of gaps and joints on coping stones as well as roof parapet walls
  • Sealing of tank bases
Key technical data:
Working life at temperatures between 5°C (41°F) to 30°C (86°F) Indefinite
Drying time 30 minutes
Tensile strength (BS 2782) 1,450 psi (10.0 N per sq.mm) lengthwise, 580 psi (4.0 N per sq.mm) crosswise
Vapor resistance at 20°C (68°F) 33 MN/sg
Recommended coverage rate (per ltr) Practical coverage rate for a 2 coat system: 
1st coat 1.3 sq.m. (14 sq.ft.) per litre on concrete and brick

2nd coat 3.0 sq.m. (30 sq.ft.) per litre on concrete and brick

1st coat 1.9 sq.m. (21 sq.ft.) per litre on asphalt, smooth felt, bitumen and metals

2nd coat 3.0 sq.m. (30 sq.ft.) per litre on asphalt, smooth felt, bitumen and metals
Bonds to Felt, asphalt, lead, zinc, copper, glass, concrete, brick and many more
Typical applications Roof repair including leak sealing, waterproofing and weatherproofing
Unit size 18ltr. Pack sizes may vary locally.
Availability* Global

* All products are subject to regional restrictions. Check with your local Distributor for more information


British Board of Agrement - ETA-05/0075


UL (Underwriters Laboritories Inc)
Class A


StarGuard™ Program Certificate

Bureau Veritas logo

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