permaculture

[Neil Bertrando <neilbertrando@gmail.com>]

Does non-arsenic mean non-toxic? my understanding is that the newer
treatment is copper based but I haven't tracked down the complete component
list or seen good info on the effects/toxicology.

not that this means it is non-toxic, but is it approved by OMRI/NOP for
Organic Production?

On Mon, Jan 21, 2013 at 8:59 PM, Stephen Sherman <spsherm@msn.com> wrote:

> I think you'll find that the commercial double glass pane units are air
> evacuated and filled with an inert gas. That makes the "middle" less
> conductive and convection loops less of an issue, which is why they can
> have 1" spacing without loosing insulating, I suspect. Unfortunately
> this is not really doable on a wood framed unit.
>
> Look carefully at the total system cost of two 1/8" sheets of polycarb
> vs the commercial dual or triple wall polycarb GH extrusions. When I
> last compared prices (granted a few years ago) the roll your own
> polycarb solution was quite a bit more expensive; which makes sense
> since you end up using 1/4" thickness of plastic overall. The commercial
> GH extrusions are quite a bit thinner than that, and use less plastic
> per sq ft of coverage.
>
> One can still put the multi-walled GH extrusions on a treated 2x frame,
> much the same way you would the single wall, you just are putting it on
> only one side of the wood structure. In CO, all new treated lumber is of
> the newer non-arsenic type for quite a few years now. I thought it was
> everywhere but you probably need to check. (The new stuff gives a
> reddish brown color to the wood, as compared to the old stuff which made
> the wood a greenish color.)
>
> Whatever polycarb you go with, you should be sure to get some which has
> a UV protected surface coating, and be sure to put that towards the
> outside as you are installing. Failure to do so will mean your plastic
> will not last as long when exposed to the sun. No plastic (clear plastic
> at least) will last forever when exposed to direct sunlight. Up here at
> 8200' elevation, the GH plastic I have has lasted 10 yrs so far and is
> still quite functional. Some say you can get 20 yrs out of it (it is
> guaranteed for 10). Interior (non UV protected) start whitening and
> cracking in as little as 5 yrs. No doubt all these times will be longer
> in places with less UV and sun.
>
>
>
>
> On 1/18/2013 9:26 PM, venaurafarm wrote:
> > On 1/18/2013 11:03 PM, Scott Pittman wrote:
> >> I have always read that any airspace between the glass or poly should
> never
> >> exceed 5/8 of an inch to prevent a thermal loop from developing which
> would
> > There is plenty of glass double pane panels that have 3/4" airspace.
> >
> >> defeat the purpose of double glazing.  This is certainly the rule in
> >> manufactured thermal pane windows and doors.  By evacuating the air
> space
> >> between the glazing panels you can slow down this effect with over time
> the
> >> vacuum gets lost.
> > My method just uses two Polycarbonate glazing attached to framing
> > members, not air evacuated. My untested theory on prevention of thermal
> > loops would be to use more framing members, blocking more light of
> > course but creating a stronger panel that is more energy efficient. I
> > would not hesitate to use this method on a skylight, in a sunspace or
> > or a greenhouse. This by far the cheapest way to go plus extremely
> > durable and lightweight; you get plenty of light with some degree of
> > thermal efficiency.
> >
> > LL
> >
> >
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