Cold-Applied Roofing

Cold-applied roofing covers any low-slope system installed without open flames or heated bitumen. The term is used for several different technologies:

• Cold-process built-up roofing: felts laminated with solvent- or water-based asphalt adhesives that are sprayed, brushed or squeegeed.
• Cold-adhered modified bitumen: SBS sheets set in cold adhesive, sometimes with special backings.
• Adhered single-ply: membranes bonded with contact or water-based adhesives.
• Liquid-applied membranes: polyurethane, PMMA, polyester, acrylic or silicone resins, often reinforced with fleece.

Advantages

The main advantage is safety: no kettles, no torches and fewer hot-work permits, which lowers fire risk and makes the work acceptable on occupied buildings such as schools, hospitals and housing. Cold adhesives also avoid asphalt fumes. In the UK, cold liquids are widely chosen for roofs, car parks, balconies and walkways where hot works are not allowed.

Limitations

Cold systems generally have stricter weather limits than hot systems. Solvent-based adhesives need time to flash off, water-based products need warm, dry conditions to cure, and rain on uncured material can spoil it. Coverage rates must be controlled; one simple site method is to mark the roof in grids matching the product's coverage rate so the right quantity goes on each area.

Reinforced cold liquids

Cold-applied reinforced liquid systems embed a polyester fleece in wet resin to form a seamless membrane. PMMA versions cure in under an hour even near freezing; polyurethane and polyester systems are also common. See liquid-applied roofing.

Health and occupancy

Because cold-applied systems avoid kettles and torches, they also avoid hot asphalt fumes, which NIOSH has identified as a potential occupational carcinogen. This makes them attractive for work on occupied buildings.