Just like the title says what is the worst moss, lichen, algae covered roof you have cleaned?

Dont think this was the worst. But its definitely top 3.

Have got to love those oak trees. 💰💰

dont know where pics are (an old laptop) but I had a slate roof that was carpeted with 3 inches of moss FULLY, and baby trees growing out of gutters! 

Old cottage house in rolling hills.

house was going on market and I suggested try to sell as is or rip off/asphalt it.

that turned out to be the best cost effective method.

I need to find those pics.

but it was worse than this...

Don't you just love those? Then go back after a few months and see a new roof.