Yes I know exactly what your thinking! That is really a tile roof under there"!    Moss from what I've seen first hand is not really that bad for tile roofs.  In this case the moss has completely consumed it though so, I am highly suggesting to the building owner to have us clean and maintain it a little more frequently!

My recommended cleaning method is;

1.  Blow, sweep and hand remove all moss.

2.  Clean out all gutters and downspouts, making sure the system is functioning properly.

3.  Pre-spray tile 1 section at a time letting dwell 15-20 minutes with a cleaning solution..

4.   Pressure rinse roof tile clean

5.  Although not in the quote, Im going to go ahead and clean the gutter fascia (outsides of the gutters) for them as well.

6.  A grounds clean up will be performed during and after the project.

Theres going to be a pile of moss 10 ft. high when were done with this!  Any body need moss?

I