Gyprock Fire Mastic fire and acoustic sealant

Gyprocksupreg Fire Mastic

Gyprock Fire Mastic is a permanently flexible, water based acrylic sealant for fire resistant caulking of penetrations and joints in masonry and plasterboard. This product provides a neutral paintable surface once cured.

As well as fire resistance Gyprock Fire Mastic can be used as an effective acoustic sealant.

Fire Mastic a low VOC, acrylic compound manufactured to stringent product specifications.

Product Options

Gyprock Fire Mastic is available in a 600ml red sausage.


Gyprock Fire Mastic is designed for sealing around pipes, conduits, busways, cable trays and ducts which penetrate walls, floors and ceilings. It will bond to plasterboard, masonry, concrete, metal deflection heads and cable coverings.


Prepare the surface by ensuring that it is dry and free from grease and dust. Cut end off caulking tube and screw on plastic nozzle. Place in caulking gun and apply to surface evenly to the required depth ratio (see this datasheet for details). Be sure that the mastic contacts all surfaces to ensure a good seal. Gyprock Fire Mastic is water resistant when cured but should not be used as a water sealing or water proofing sealant.

To ensure that the mastic cures correctly, it should not be applied if the room temperature is less than +5 degrees celsius or in high humidity/moisture conditions. In some joints, foam backing rod may be required as backing material.

Comprehensive installation instructions for Gyprock plasterboard and compounds can be found under the Resources tab and include:

For assistance with installation, try searching for a Gyprock plasterer, builder or repairer under the Locations tab.​



  • Gyprock products are manufactured for life with all CSR products designed to achieve optimal performance when part of a CSR integrated system
  • All Gyprock jointing products exceed the GBCA specification for Volatile Organic Compound content according to independent testing. Test certificates are available under the Resources tab.