Why High Pressure is Harmful to Your Roof

High pressure on a roof is one of the most common and costly mistakes a homeowner — or poorly informed contractor — can make. Here's why, with facts to back it up.

Granules: the protection you only get once

Asphalt shingles are covered with mineral granules that serve three essential roles: UV protection, fire resistance, and heat reflection. High-pressure washing strips these granules irreversibly. Once gone, they don't come back. You can see granule loss in your gutters after aggressive high-pressure washing.

Manufacturer warranty cancellation

Major shingle manufacturers (IKO, BP, CertainTeed, GAF) explicitly mention in their warranties that damage caused by high pressure is not covered. Some go further and specifically recommend the Soft Wash method (SH + surfactant) as the only acceptable cleaning method.

What high pressure doesn't fix

The real problem with black streaks, moss and lichens is not surface dirt — it's a living organism rooted in your shingle. High pressure can visually displace some of it, but within months, the organism regrows from its intact roots. Results last 6 to 12 months maximum. Soft Wash with SH lasts 3 to 5 years because it destroys the organism chemically.