[Greenbuilding] roof material for rain harvesting

[Michael O'Brien]

Hi, Tim--

Here's the whole history of research on aluminum and health:

www.ncbi.nlm.nih.gov/pmc/articles/PMC3056430/

Kind of technical, but Section 4 is a summary. Short version: better to avoid ingesting Al.

But, does gavalume roofing actually shed Al?

Best,

Mike

Mike O'Brien Photography
mikeoregon.zenfolio.com




On Aug 16, 2013, at 5:53 PM, candtcampbell at juno.com wrote:

> Thanks for the replies everyone. Nick, the link you gave isn't working - can you correct it? I think the reason galvanized is recommended over galvalume, or zincalume as Nick calls it, is that neither humans nor vegetables require dietary aluminum, and some say it's actually toxic to humans. So I'd still like to find plain galvanized. However, I'm not going to be bending pans myself, and am reluctant to seek someone to do it for me, so would like to find this on the open market. If I have to use exposed fasteners, then I have to deal with leaching from neoprene, and I don't know whether that's worse than eating aluminum.
> 
> Tim
> 
> On 8/15/2013 10:15 PM, candtcampbell at juno.com wrote:
>> I've read that the best roof for rain harvesting is simply unpainted
> galvanized steel (not galvalume).
>> Is anyone aware of such material intended to be installed with concealed
> fasteners?
> 
> All new construction around here has rainwater tanks these days, but the
> rarity of plain vanilla gal roofing, and the great plethora of zincalume
> surely makes one wonder about the above. Essentially, Zn/Al steel imparts
> corrosion resistance of up to four times the life of galvanised steel and,
> most particularly, Zn/Al is also more resistant to acidic rain than straight
> Zn.  All this is reflected in the manufacturers' guarantees or the lack of
> same.
> 
> Both colorbond steel and zincalume steel are kosher for the collection of
> drinking water under local standards AS/NZ 4020 - 1999 "Products for use in
> contact with drinking water" and thus I imagine good enbough for anywhere.
> 
> While corrgated roofing has exposed screws, ribbed metal deck can be had
> with concealed clips.
> 
> Some background    http://www.u.com.au/files/dmfile/CTB25june2008.pdf
> 
> Nick Pyner
> 
> Dee Why   NSW
> 
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