[Greenbuilding] roof material for rain harvesting

Nick Pyner npyner at tig.com.au
Fri Aug 16 01:10:00 CDT 2013


-----Original Message-----

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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