Hot Weather Recommendations for Application of Asphalt Roofing Shingles

Technical Bulletin #30

Current as of July 2021

Asphalt roof shingles have been used successfully in various climatic zones around the world for many decades, including desert and tropical regions. Improved application efficiency, and more importantly, enhanced long-term shingle performance can be achieved by following some of the hot weather application recommendations outlined below.

  1. Storage. Although asphalt shingles are designed to withstand direct exposure to the hot summer sun once installed, it is best to not store the products in direct sunlight. Such severe storage conditions can weather and weaken the packaging materials, making it awkward to carry/move the bundles prior to installation. As well, even though the shingles have a release film to prevent the shingles from sticking to each other in the package, in direct sun sealant will become more aggressive, and the shingles can be more difficult to separate out of the bundle. Always follow the manufacturer’s precautions about stacking bundles too high. Double-stacking pallets can indent/deform the shingles over time, particularly in warm weather.
  2. One must always be careful when working on pitched, sloped roofs. In hot weather applications, the asphalt coating on the shingles may become slightly softened, allowing for potential foot slippage. Wear proper footwear to minimize foot slippage possibilities. Also, under direct sunlight the asphalt shingle coating may be softened slightly rendering the shingles susceptible to scuffing from roof work or foot traffic. This is especially true on steeper roofs where worker “footprints” are likely to be more concentrated in small areas (toe marks, heel marks). Use reasonable care to minimize any scuffing, and if necessary, wait until shingles and ambient temperature cool down.
  3. For obvious comfort reasons, and for safety reasons noted above, on forecasted hot/sunny days it is advisable to install shingles early in the day before the temperature reaches its maximum. One should also plan the roof installation to “work around the sun”, i.e. work on the western-facing slopes in the morning, and the east-facing slopes later in the day.
  4. Despite trying to work around the sun or starting earlier in the day, shingle bundles will likely be laying in the sun for some length of time prior to installation. When removing shingles from the warm bundle, follow the manufacturer’s recommendations, as some products may separate better/easier when removed from the bundles ‘granule side up’, or by quickly snapping the shingles out of the bundle stack. This helps “shear” any tacit sealant bond which may be forming between shingle sealant and release films, allowing easier separation, and minimizing potential shingle damage.
  5. Almost all asphalt shingles are manufactured with a thermally activated asphaltic sealant which bonds the shingles together once applied to the roof and exposed to a few weeks of sufficient heat from sunlight. Even on hot sunny days, if the sealant has been covered by wind-blown dust from the surrounding environment or the job site (saw dust, etc.) or other air-borne debris, the sealant may not activate properly, and the shingles will need to be manually sealed as per the shingle manufacturer’s instructions. As well, on north-facing slopes or steeper slopes the shingles may not seal immediately, even in warmer weather.
  6. If repairs or other roof-top work is required during hot sunny weather, it is likely that the sealant bond is fully formed. Shingle removal/repair will be difficult to perform without causing shingle tearing/damage at the sealant interface. In such cases it is therefore often best to wait until cooler temperate conditions prevail before attempting shingle repair. Use of a watering hose and cold water to cool the shingle surface in very hot conditions is a technique that may facilitate the bond separation.
  7. Finally, ensure your safety by following all required safety precautions which may include use of fall protection devices.

The information contained in this bulletin is for general education and is not intended to replace advice from a qualified contractor or direction on usage/installation from the manufacturer. Consumers should be aware of the safety hazards associated with work on roofs and, before doing so themselves, should consider following CASMA s advice of using qualified contractors. This bulletin may be reproduced with permission on condition that it be reproduced in whole, unedited, with attribution of copyright to CASMA.