Ken,
What is being done?  As for PM, there is a unit price developed by a
facilities guy at the Pentagon.  He figured out that the optimal amount of
money you should spend on maintenance of a flat roof was 15 cents per foot.
The opportunity cost of not maintaining it resulted in 45 cents per foot per
ten year period.
How about the moss roof in Germany?  Hey!  My gardens leaking.  Where do you
think its getting in?
Best,
Leland