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EPDM Roofing

Water Cut Off Mastic

Water Cut Off Mastic

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DuoPly Water Cut Off Mastic is a one part butyl blend mastic designed to be used in conjunction with EPDM roofing and waterproofing systems. It is primarily used for sealing between membranes when installing a compression type seal.

Water Cut Off Mastic is extremely tacky and will remain as such when not under compression.

Features & Benefits

  • Provides a durable compression type seal
  • Extremely tacky
  • Coverage of 3 linear metres per tube


1. All surfaces must be free of moisture, oil, dirt and other contaminants. Water cut off cannot be used on insulation and needs to be compressed against a solid, nonporous surface.

2. Apply a 11mm bead of Water Cut Off Mastic between the substrate and the underside edge of the membrane. The fleece needs to be removed from back of membrane for this application.

3. Apply appropriate DuoPly termination bar and secure to provide constant compression to the Water Cut Off Mastic.


1. Review the applicable Material Safety Data Sheet for complete safety information prior to use.

2. Water Cut Off Mastic is flammable. It contains solvents that are dangerous fire and explosion hazards when exposed to heat, flame or sparks. Store away from all sources of heat, flame or sparks. Do not smoke when applying. Do not use in a confined or unventilated area. Vapors are heavier than air and may travel along ground to a distant ignition source and flash back.

3. If swallowed, do not induce vomiting. Contact a doctor immediately.

4. Avoid contact with eyes. Safety glasses or goggles are recommended. If splashed in eyes, immediately flush eyes with water for at least 15 minutes. Contact a doctor immediately.

5. Avoid contact with skin. Wash your hands thoroughly after handling. In case of contact with skin, thoroughly wash affected area with soap and water.

Colour: Grey
Solids: 80%
Flash Point: 4°C
Service Temp: -40°C to 93°C
Shelf Life: 1 year

Download the DuoPly Brochure

Registered in England and Wales, Company Number: 03984573

Registered Office: Flex-R Ltd, Sandswood House, Hillbottom Road, Sands Industrial Estate, High Wycombe, Buckinghamshire, HP12 4HJ

Telephone: 0800 037 1240   Email: enq@duoply.co.uk