[permaculture] Roofing materials and water collection

Gene Monaco efmonaco at comcast.net
Sat May 14 20:31:17 EDT 2011

Does anybody have any long-term experience with Galvalume.
I have three concerns and no answers:
1) Since it is 55% Aluminum-Zinc alloy-coated sheet steel, the aluminum
might leach into the water giving us Alzheimer's.
2) How does it weather over time.  There are a lot of raggy looking metal
roofs out there.  It might be good for a while, and I know that nothing
lasts forever, nor should it, but what does it look like after 20 years?
What happens as it deteriorates?
3) Seems like a lot of embodied energy (high carbon footprint).  Aluminum
from far away...

Date: Sat, 14 May 2011 07:57:13 +0100
From: harry byrne wykman <lists at peacetreepermaculture.com.au>
Subject: Re: [permaculture] Roofing materials and water collection
To: permaculture at lists.ibiblio.org
Message-ID: <20110514075713.59a55dbf at humilis>
Content-Type: text/plain; charset=UTF-8

Here's a quote from a write-up of a recent study:

Cockrell School faculty and students conducted an in-depth study --
recently published in the academic journal Water Research -examining
the effects of conventional and alternative roofing materials on the
quality of harvested rainwater. The study, led by civil, architectural
and environmental engineering Assistant Professor Mary Jo Kirisits,
showed that, of the five roofing materials tested, metal (specifically
Galvalume??), concrete tile and cool roofs produce the highest
harvested rainwater quality for indoor domestic use. The study also
showed that rainwater from asphalt fiberglass shingle roofs and
increasingly popular "green" roofs contain high levels of dissolved
organic carbon (DOC). Although other potential pollutants can be
significantly lower on green roofs (turbidity and aluminum), the high
DOCs are significant where these roofs would be used for potable
rainwater collection.

Source: Rainwater harvest study finds roofing material affects water
quality : www.sciencedaily.com


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