Fire Mastic

Gyprock Fire Mastic is a permanently flexible, water based acrylic sealant for fire resistant caulking of penetrations and joints in plasterboard and masonry surfaces.

Typical Applications

Gyprock Fire Mastic is designed to create a fire resistant seal 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.

Category: CSR, Adhesives & Sealants
Store availability: Cabramatta, Katoomba
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Gyprock Fire Mastic is an off-white, low VOC, fire and acoustic acrylic grade sealant manufactured to stringent product specifications. It has a working life of 30 minutes and a skin time of 15mins. It provides a neutral paintable surface once cured.

Extensively Tested

Fire Testing
Gyprock Fire Mastic has been tested for periods of up to four hours, in systems, in accordance with AS1530.4 and achieved the following fire resistance levels (FRL):

– Plasterboard systems up to FRL 120/120/120.
– Masonry systems up to FRL 240/240/240.

Mechanical Testing
Tests to AS4072 have shown that Gyprock Fire Mastic has movement capabilities of ±20% after curing, which means that this product remains flexible and resists cracking.

Product Options

Gyprock Fire Mastic is available in a 600ml sausage and has a shelf life of 12 months from date of manufacture.

For product availability and to place an order, contact your nearest supplier.

Physical & Chemical Properties

Appearance Off White paste
Working time Skin time = 15mins, Working time = 30mins
Joint movement capability +/- 20%
Elongation at break >400%
Modulus <0.4MPa at 100% elongation, fully cured. 0.8MPa max modulus.
Viscosity 750,000 – 950,000cP
Specific gravity (H20=1) 1.50 – 1.60
Acoustic rating Rw Tested to Rw + Ctr 55 as a gap sealant in a wall system.
Fire rating* Up to FRL -/240/240 FRL when tested as a control joint to AS1530.4 supplemented by AS4072.1 and BS476: part 20.
Halogen free Yes
VOC content (as specified by GBCA) 31g/L
Service temperature -20 to 80oC
Hardness (Shore A) 23 – 35

* for 10mm x 10mm joint in concrete. For full details on FireSeal suitability, fire and acoustic performance, mandatory system requirements or applicable system warranties for all products or building systems within CSR, please refer to the relevant design guides published by Hebel®, Gyprock®, Bradford™ or Cemintel™.

Product Manufacture

FireMastic is manufactured for CSR Gyprock in Australia to stringent product specifications.

Product Handling

Transportation and manual handling: Refer to the Gypsum Board Manufacturers of Australia (GBMA) website for recommended OH&S practices.

Storage: Store unopened sausages below 30°C in a cool dry place away from direct sunlight. Opened sausages may skin and form a lump near the opening. Discard any lumps or skin and remaining product can be used.

Health and Safety

Safety Data Sheets are important documents in the construction industry and assist in the continuing focus on occupational health and safety on and off sites.

Installing to Standards

AS/NZS2589: Gypsum linings – Application and Finishing outlines the procedures for jointing and finishing of Gyprock plasterboard in conjunction with additional details contained in Gyprock Technical Literature.


Gyprock makes available resources that provide comprehensive selection, design, installation and maintenance guidance.

Product Enquiry

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