Intumescent Mastic, Fire Rated & Sealants. Standard construction foams and mastics provide little or no fire resistance. The range of products on this page can be used where fire stopping properties are required, for example, mastic sealing around other fire rated products. The PFP FR Acrylic is designed to prevent the spread of fire and smoke through joints and openings in fire rated walls and floors. The Intumescent Mastic is fire resistance to EN 1366-3 : 2009 and EN 1366-4 : 2006 and comes in various colours. The Intumescent High Pressure Expansion Sealant is used for for pipework up to 125mm diameter and suits metallic, PVC, HDPE and ABS pipes. All our mastic's are CE marked for more information or technical help please contact us.