Hot Weather Roofing

Roof surfaces can be far hotter than the surrounding air, and roofing is one of the trades most exposed to heat. Hot weather affects both people and materials, and roofing practice in hot climates, from the southern United States to the Middle East, Australia and South Asia, is organised around it.

Heat stress

The US Occupational Safety and Health Administration (OSHA) promotes water, rest and shade to prevent heat illness. Its guidance recommends scheduling heavy work for cooler times of day, shortening shifts, and taking frequent breaks in shade. New and returning workers need acclimatisation, with shorter shifts and frequent breaks during their first days in the heat. OSHA notes that wet bulb globe temperature (WBGT) is the most accurate measure of heat stress, and some US states, including California, Washington, Oregon, Minnesota and Colorado, have specific occupational heat rules. Federal enforcement relies on the general duty clause and a national emphasis programme on heat hazards.

Typical roofing measures include early starts, rotating tasks, cool drinking water at roof level, shaded rest areas, buddy checks for symptoms of heat exhaustion and heat stroke, and light-coloured, breathable clothing worn with the required personal protective equipment.

Materials

• Asphalt shingles soften in high heat and can be scuffed or marked by foot traffic, especially on dark colours. Crews limit walking on newly laid shingles, avoid twisting on the surface and stage materials to minimise traffic.
• Sealing. Factory sealant strips activate quickly in heat, so shingles misaligned during installation can bond in place before they are corrected. Excess hand-applied cement can cause blistering and should be used sparingly.
• Bitumen and adhesives. Hot conditions shorten open times for adhesives and coatings, and some coatings have maximum surface temperature limits.
• Metal panels. Panels expand on hot days; clip and fastener layout must allow for movement. Metal surfaces can cause burns.
• Membranes. Hot-air welding settings for thermoplastics are adjusted to conditions, with test welds after significant weather changes.

Storage

Bundles and rolls are stored flat, out of direct sun where possible, and not stacked higher than the manufacturer allows, since heat combined with weight can cause sticking and distortion.