Should I pressure wash my asphalt composite roof?
Simply put the answer is NO.
Asphalt shingles, unlike wood shakes are manufactured with components that create a roof system.
asphalt composite shingle starts out as a woven fiberglass sheet nearly
1/8” thick. The fiberglass is saturated on both sides with asphalt. The
top layer of asphalt, while still molten is embedded with Ceramic
Granules have 2 functions:
- 1. To give the shingle it’s color.
- 2. To protect the asphalt from the harmful UV rays of the sun.
with the granules, Asphalt is the waterproof component of the shingle,
and the Fiberglass is the chassis that holds the shingle together.
is a very volatile product (meaning that it is easily affected by heat
causing change in viscosity and increasing expansion and contraction)
and when granules are missing and there is more UV exposure the asphalt
gets dried out and causes roof failure.
Pressure washing a roof
when done improperly minimally removes granules that are so important to
the longevity of your roof. Because asphalt composite is a thin product
that can be easily torn it is not too difficult to cut the shingles
with the pressure wand.
Many pressure washers will assure you
that they are experienced and will not cause damage. They may be right,
but how can they guarantee it?
The adhesion of granules reduces
as the roof ages. The challenge for a pressure washer is how to gauge
their pressure. The problem for you is HOW WOULD YOU KNOW IF THEY ARE
DOING IT RIGHT?
It is difficult to know. The big question is, why
pressure wash anyway? The only reason is that it is a quick fix. Quick
fixes typically come with a bill to pay later.
Maybe it would be
better to examine where moss comes from, and what can be done from a
preventative standpoint to keep your roof healthy and looking clean.