Asphalt Roofing Temperature


Correct application temperature is critical. Moderately higher temperatures destroy asphalt.


It has been recognized for some time that overheating asphalt changes its physical characteristics as well as decreases the weathering life of roofing material.


Manufacturers require an “equiviscous temperature” within +/- 25℉, yet asphalt cools 100 degrees in 5 seconds, 200 degrees in 11 seconds


(Source: National Bureau of Standards)



Test samples overheated by 100 degrees for 4 hours completely failed

after the equivalent of one year average outdoor exposure

  

This test was made by heating the asphalt for four hours before placing it in a weatherometer.


Weathering is reported in cycles. One cycle (24 hours) in the weatherometer equals approximately 21/2 weeks of weather life. Twenty cycles are equivalent to one year of average outdoor exposure.


    Asphalt heated at 450℉ taken out at the end of 80 Cycles showed no apparent decrease in weathered life.


    Asphalt heated at 550℉ for 4 hours failed at 20 Cycles.


    Asphalt heated at 600℉ for 4 hours failed at 10 Cycles.