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permaculture - Re: [permaculture] Roofing materials and water collection

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  • From: "Lawrence F. London, Jr." <venaurafarm@bellsouth.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Roofing materials and water collection
  • Date: Fri, 13 May 2011 21:23:07 -0400

On 5/13/2011 7:49 PM, Stephen Sherman wrote:
We have a small building which is going to be roofed, and I am in the
middle of choosing a roofing material. I would like to keep the option
of collecting roof runoff open, and keep the roof as fireproof as
possible. Those are the primary concerns for this choice of roof.

1)
I have heard/read the negatives about using water which came off asphalt
shingle roofs, so those are probably not an option. That would seem to
leave only a few choices:

2)
Ceramic tile roofs are out, due to their weight and structural concerns.

3)
Galvanized metal roofing seems like the best choice perhaps, for easy of
use, fireproof-ness, and runoff quality (as far as I have heard).

4) The Best Choice
Another potential option is painted metal roofing (usually available in
wider sheets than the plain galvanized, and longer lasting. Only problem
is no manufacture seems to have any data about runoff water quality from
their painted roof materials.

I would avoid asphalt/fiberglass etc.; ceramic is not really an option, plain 5V (24") galvanized will rust and require maintenance

Painted, galvanized (I assume it is galvanized under the paint layer) metal roofing comes in any length and in 38" width with 5 separate, evenly spaced gullets (rounded ridges) affording many overlap options to accomodate roof framing specs without cutting the roofing panels lengthwise which would bugger up the edge and break the paint coat. This is maintenance free and will last a lifetime. It may be heavier gauge than 5V and for sure you can get the industrial grade of this type of roofing that is very heavy gauge and with deep square overlapping gullets; this last option will last hundreds of years. I have used both 5V and painted but will only used the prepainted for any new work or maintenance. If you have to cut any to fit framing then use a simple curcular saw with a sheet metal cutting blade. Works fine. It is a flat smooth/square edged disk with many short slots cut around the edge radially toward the center. It cuts by tearing or ripping and not by abrasion. You can use this blade to cut panels lengthwise and across.
The fastener system ussed to attach the painted metal panels is superior to that available for the 5V, partly because of the limitations
imposed by the V's, only leadhead, acorn or neoprene washer nails are available though now there may be neoprene washer galvanized screws to use. This latter fastener, though heavier gauge than used for 5V, is what is used on the 38" painted metal panels. They say you can screw them through the flats but I would never do that, only through the overlapped V gullets (they are more like U gullets).
I can take photos of both metal systems if you want to see what they look like installed and which has rust and which doesn't.

I was wondering what people thought about these options; If there are
any others which I've missed; and if anyone had any hard data on
painted metal roofing leaching whatever into the water runoff.

From my experience and knowledge 5 U galvanized/painted 38" metal roofing is the very best option, nothing else can come near for ease of installation and durability as well as giving the owner-builder more and better design options.




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