Can Classicbond EPDM Be Laid on Felt?

ClassicBond EPDM can be installed on a variety of roof surfaces, including timber OSB3 or plywood, concrete, metal, GRP, glass and tissue-faced insulation. Its versatility makes it a popular choice for new builds, renovations, and roof repairs.

However, ClassicBond EPDM is not suitable for direct application onto felt or bitumen-based surfaces. The bitumen content in felt can react negatively with EPDM over time, potentially causing the membrane to degrade or fail prematurely. This reaction occurs regardless of whether the EPDM membrane is 1.2mm or 1.5mm thick.

If you need to overlay a felt roof, these are your reliable options: 

• Overboarding: Install a separation layer, such as OSB3 or plywood, before applying ClassicBond EPDM. This provides a clean and fresh surface.

• ClassicBond Pro - Fleece-backed membrane: ClassicBond Pro can be installed directly onto felt or bitumen. The fleece creates a separation layer between the substrate and the EPDM layer of rubber. 

These options ensure a durable, long-lasting roof, even over existing felt.