[sweaty]

My roof is covered with black algae. It's way too big to wash by hand. Can/should I pressure wash it?

 

[Ed the Roofer]

You would be better off with a garden hose hooked up to an algae killing agent liquid dispersed at low pressure.

Their are products made for just roof cleanings, but with mixed results.

If you use a high psi pressure washer, you may damage the shingles by scouring the granules off with the algae embedded to the organic surface material.

Ed