For fire and acoustic applications, the sealant used must have appropriate performance, and supporting documentation to show it meets the relevant standards and specifications. Fire rated sealants require a fire performance rating according to AS1530.4, and acoustically, a sound insulation rating calculated according to ISO-717.
Fire rated sealants however, can differ greatly in their physical performance characteristics (such as adhesion and flexibility), and these are just as important in sealant selection, as they are key in providing a robust sealant that will adhere and maintain adhesion integrity. In most applications, whether it is a penetration or perimeter seal, the sealant will need to have the ability to wet out and adhere to friable surfaces such as the cut edge of plasterboard. In the event of building element movement that puts strain onto the sealant, the adhesion to the cut edge needs to be strong enough to maintain the integrity of the seal.
Adhesion integrity to friable surfaces is influenced by the flexibility of the sealant. A useful quantitative measure of a sealant known as Modulus, describes the ease with which a sealant can flex under the influence of force, and is referred to as being either low or high. A low modulus product is easy to flex whereas a high modulus sealant is more difficult to flex. Therefore, a low modulus sealant has the propensity to flex before the bond to friable surfaces can rupture.
After a sealant has been applied and the wall complete, the sealant will often be hidden and there is no way of knowing whether the sealant has maintained its bond integrity long after construction has finished.
Failure of the system will only be evident after complaints about acoustics or in the unfortunate event of a fire. Selleys® next generation sealant—Proseries™ Fireblock®—not only meets the standards for fire (AS1530.4) and acoustic performance (STC 67), but also offers enhanced performance of adhesion and bond integrity to the plasterboard cut edge, even under adverse building movement. In addition, Proseries™ Fireblock® contains a unique UV tracer which provides security that the correct product has been used.
Contact your nearest CSS member store for more information on Selley’s range of fire rated sealants.