It s the ultraviolet radiation that they re subjected to all the time.
Roof temperatures in summer.
The maximum sheathing temperatures recorded were 168 f 76 c for black shingled roofs and 147 f 64 c for white shingled roofs.
Different sources report different temperatures.
An unshaded roof can reach temperatures of as much as 65 to 90 c.
Here s the kind of temperatures you can expect your roof to reach this summer depending on its surface.
This actually speeds up the effects we looked at in the last paragraph.
At these temperatures asphalt shingles can melt.
This fsec study didn t look at shingle lifetime but i think that adding 9 degrees to a temperature of 150 degrees won t make much difference.
Your roof bears the brunt of the sun s force and is exposed to a lot of heat during the summer.
Color of your roof.
A roof without shade might get up to 160 degrees f when the outside air temperature is only 90 degrees.
This also speeds up the damaging effect of the uv rays and causes other problems.
Roofs that absorb more heat in the summer will also absorb more heat in the winter which can actually be a wonderful positive when it comes to melting snow and keeping your home toasty warm in the winter.
Degrees fahrenheit on a sunny 90 degree day.
Overall the plywood sheathing in black shingled roof systems tended to be 10 f to 15 f 5 c to 8 c warmer dur ing the midafternoon of a sunny day than the plywood in comparable white shingled roof systems.
An unventilated attic can also exacerbate the problem and make damage more likely.