[Greenbuilding] Insulation Problems
William R Bloom
wbloom at unm.edu
Thu Nov 11 12:40:52 CST 2010
Weren't they talking about continuous insulation on the
inside surface? I would have to agree about the thermal
break from the z-bars, particularly with COPPER cladding,
but if they put another layer of foam on the inside, then
a layer covering the exterior would be redundant?
On Thu, 11 Nov 2010 11:57:08 -0500
"J Messerschmidt" <John at fourpointscg.com> wrote:
> Alan,
> That's not a bad idea. I think it's fair to say that
>the insulation value is being reduced from R10 to what,
>an R6 - due to the heat transfer of the metal bars. I
>think the key is whether we can safely tape the joints to
>provide continuous insulation, while allowing drying to
>the outside. What's your opinion on that?
>
> Thanks!
>
> John
>
>
>
>
> ----- Original Message -----
> From: Alan Abrams
> To: J Messerschmidt
> Cc: Thomas Lewis ;
>greenbuilding at lists.bioenergylists.org
> Sent: Thursday, November 11, 2010 11:23 AM
> Subject: Re: [Greenbuilding] Insulation Problems
>
>
> building on John S's comments...
>
> ...are there some semi rigid strips of something like
>neoprene that could be applied over the outside face of
>the z-bars, that would have sufficient resistance to
>compression to support the cladding yet still provide
>some thermal breakage before the cladding is attached?
> this assumes that the potential for heat loss through
>the bridges is so great that even the addition of R-0.5
>btwn bars and cladding would be significant.
>
>
> AA
>
>
>
> Alan Abrams
> Abrams Design Build LLC
> A sustainable approach to beautiful space
> alan at abramsdesignbuild.com
> www.abramsdesignbuild.com
> 202-726-5894 o
> 202-437-8583 c
> 202-291-0626 f
>
>
>
>
>
> On Thu, Nov 11, 2010 at 11:02 AM, J Messerschmidt
><John at fourpointscg.com> wrote:
>
> Hi Thomas,
> I love the suggestion of taping the seams and taping
>the board to z bars. With the air leakage to the outside
>eliminated that would bring us a lot closer to the r-10,
>and it would be a proper drainage plane. My concerns
>are, what kind of tape and how does water escape if it
>does get in? 2" of xps has permeance of .55. Will that
>allow vapor to escape? What about bulk moisture? Behind
>the xps is a liquid applied membrane that probably has a
>very low permeance, so it has to dry to the outside.
>
> Lastly, looking at the interior wall assembly, if the
>open cell foam has a perm rating of 8, and 1" of polyiso
>has a perm of 2.33, this could be a well insulated wall
>and will still dry to the inside. Right? Unless I'm
>missing something, we'd end up with about an R30 wall.
> I'd be very happy with that. What do you think?
>
>
> Thanks!
>
> John
>
>
>
More information about the Greenbuilding
mailing list