If your membrane roof is external, it would seem more likely that the whitish/lime green growth is lichen.

 

This is unlikely to damage the roof membrane in any significant manner … and indeed, it may provide some protection against ultraviolet radiation induced deterioration (although since you say the roof is in shade; and you live in those northern climes), you probably don’t have much UV to worry about.

 

Cheers

 

David West

Executive Director

internationalconservationservices

T:     +61 (2) 9417 3311

M:    +61 (411) 692 696

sustaining your heritage

From: The listserv where the buildings do the talking [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Friday, 28 August 2009 4:27 AM
To: [log in to unmask]
Subject: [BP] mold on membrane roofing

 

 

There is a nice whitish/lime green mold growing on a 9 sq foot section of my 20-yr old flat membrane roof.   Although there is an annoying live oak above it, the tree actually overshadows the entire 400 sf porch, so i cannot figure out why it grows there.

 

Should I gently scrape it off?  Or leave it alone?

 

c on dfi, getting ready for hurricane danny and moving malia's stuffed animals to high ground

 

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