Great work Juan:-)
A follow up on how to remove staining and why the staining was created would be an idea.
As for pressure washers. Even at a low rate of pressure you are degrading the the top layers and possibly hastening the delamination of 2 things, The top coating that protects from UV for one and unsealing the shingles.
Tree’s & atmospheric conditions most likely the culprit.
Now James Write up your report with what you observed and from where.
Ground, Ladder that the eave.
Report on condition. No speculation of what may occur.
Home inspections are the visible condition of the components on “the day of the inspection.”
IE: A home owners buyers the home and places on a new roof on the unit because they want to, not need to or have to, have piece of mind for 20 tears.
A report may read as follows: The 12/12 pitch roof architectural shingles appeared to be in good condition.
SUSPECT: 2 deficiencies;
#1 Valley are closed. A shingle valley is recommended to be open.
A parallel line is marked 2" off center of the valley from the bottom to the peak of the roofs deck… The excess asphalt shingle is cut away exposing the metal under the shingles. This exposed metal allows debris form tress such as leaves, seed pods, small pieces of wood, ice and snow to be removed more readily by atmospheric conditions IE: Wind and rain.
#2 Algie staining on the front left hand gable.
Algie staining can be removed without harm to the asphalt shingles. There are several methods used to remove the algae.
Add a link. Bob’s your uncle mate
If you know the shingle manufacture do a class action search. Nathan has a service I recommend to all HI’S. RECALL CHECK.
I recommend that pressure washing is avoided at all costs. I have an commercial pressure washer. I can reduce the pressure to 150 LB. SQ.IN.
I have the basic principles of proper application and maintenance for sloped and flat roofing. I have my roofing trades licence.
I personally would never pressure wash a shingle roof let alone other components of a building unless you know what you are doing.