The Torch-On Talc Felt 4mm Underlay 8m is a heavy-duty, high-performance base layer designed to provide a secure foundation for multi-layer flat roofing systems on extensions, garages, and sheds. Measuring 8 meters in length with a robust 4mm thickness, this underlay is engineered with a high-tensile polyester or glass-fibre core that offers exceptional strength and flexibility. It effectively accommodates natural thermal movement within the roof structure while delivering a tough, resilient first stage of defense against moisture ingress.
 
The upper surface of the membrane is finished with a fine talcum powder dusting, which prevents the layers from sticking together while tightly rolled and ensures smooth unrolling during installation. Meanwhile, the underside features a specialized melt-off plastic film that burns away easily when activated with a roofing torch, creating a strong, uniform, and seamless bond with the roof deck or previous layers. This makes it an efficient and reliable choice for professional roofers and experienced DIYers alike.
 
Working in synergy with a heavy-duty mineral cap sheet, this 4mm talc underlay significantly enhances the overall weatherproofing, stability, and wind-uplift resistance of the entire roof assembly. It protects underlying timbers from dampness, leaks, and condensation, helping to extend the lifespan of the flat roof system. Whether you are installing a brand-new roof or undertaking a complete refurbishment, this high-quality underlay delivers trade-grade reliability and peace of mind.