[Greenbuilding] Polyiso strength on roof

[ErgoDesk]

Build the entire House from EPS http://goo.gl/bpmmmJ

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On Mon, Dec 8, 2014 at 7:01 AM, John Salmen <terrain at shaw.ca> wrote:

> Its funny as its thought that the expanding agent causes the decrease and
> as the blowing agent outgases over time the performance drops as well. EPS
> improves in cold weather. Here is a link to the building science realer
> world tests summary
> http://www.buildingscience.com/documents/special/thermal-metric-documents/thermal-metric-summary-report
>
>
>
>
>
> *From:* Greenbuilding [mailto:
> greenbuilding-bounces at lists.bioenergylists.org] *On Behalf Of *Alan Abrams
> *Sent:* December-08-14 6:14 AM
>
> *To:* Green Building
> *Subject:* Re: [Greenbuilding] Polyiso strength on roof
>
>
>
> and now comes Building Green, to out the news on polyiso: that its
> performance plummets as the temperature drops...
>
>
> http://www2.buildinggreen.com/article/polyiso-manufacturers-turn-blind-eye-problems-cold-temperatures?utm_source=BuildingGreen.com%20Mailing%20List&utm_campaign=c7088d50b1-BGB_2014_12_08_members&utm_medium=email&utm_term=0_d558b0594a-c7088d50b1-157062105&mc_cid=c7088d50b1&mc_eid=d0e88c5192
>
>
>
> -AA
>
>
> Alan Abrams
>
> *certified professional building designer, AIBDcertified passive house
> consultant, PHIUS*
>
>
> *certified passive house builder, PHIUS*cell     202-437-8583
> alan at abramsdesignbuild.com
> HELICON WORKS *Achitecture and Education*
> <http://www.heliconworks.com/index2.html>
>
>
>
> On Sun, Dec 7, 2014 at 5:53 PM, Sacie Lambertson <
> sacie.lambertson at gmail.com> wrote:
>
> Recommend highly staggering the EPS on the roof, using the foam
> sealant/glue John mentions AND covering all with thick layer (s) of felt.
> We have had a condensation problem with a similar combination (metal roof
> attached to straps etc).  I am pretty sure it is because the foam was not
> staggered and or sufficient foam/glue was not used in all the nooks and
> crannies.  Needs some real hands on supervision and frankly better if the
> details are handled by you rather than the construction people.
>
>
>
> Plywood not necessary.
>
>
>
> We're in NE Kansas.  Lots of wind.
>
>
>
> Sacie
>
>
>
> On Sun, Dec 7, 2014 at 9:03 AM, John Salmen <terrain at shaw.ca> wrote:
>
> I would strongly recommend eps rather than polyiso for the roof insul.
> There are a number of benefits you can research. 2” foam can span the 5.5
> centres but I would bond the staggered foam layers together using some foam
> adhesive (spray poly foam works well). Depending on the type of metal
> roofing (fastening) it could be laid directly on the foam (with a wrb)
> eliminating the ply layer. Metal roofs are very prone to condensation
> inevitably wetting the sheathing so the ply is a weak component. If ply is
> used a a very well applied wrb is crucial (membrane). The ply is really
> just there for fastening so if a z strip or other fastening system could be
> used it would minimize material in the assembly.
>
>
>
> John
>
>
>
>
>
> *From:* Greenbuilding [mailto:
> greenbuilding-bounces at lists.bioenergylists.org] *On Behalf Of *Ron Cascio
> *Sent:* December-07-14 9:45 AM
> *To:* 'Green Building'
> *Subject:* Re: [Greenbuilding] Polyiso strength on roof
>
>
>
> Sounds good to me.
>
>
>
> Ron
>
>
>
> *From:* Greenbuilding [
> mailto:greenbuilding-bounces at lists.bioenergylists.org
> <greenbuilding-bounces at lists.bioenergylists.org>] *On Behalf Of *Bill
> Allen
> *Sent:* Sunday, December 07, 2014 10:52 AM
> *To:* Green Building
> *Subject:* [Greenbuilding] Polyiso strength on roof
>
>
>
> Hi all
>
> I am about to reroof my 1926 colonial and am looking to also insulate per
> the BSC "deep energy retrofit" plans consisting of plywood sheathing, 2
> layers of 2" polyiso, another layer of plywood, then roofing (in my case,
> standing seam metal roofing).
>
> The original roof was wooden shingles that are still in place with 2
> layers of asphalt on top. Also still in place are the nailers for the wood
> shingles...roughly 1x2s, 5.5" on center across the rafters.
>
>
>
> My question is: if I leave the 1x2 nailers in place during the demo can i
> exclude the first layer of plywood and install the polyiso directly on the
> nailers? It would then have plywood on top, secured with long screws into
> the rafters. Less material and less cost.
>
>
>
> Thanks for any thoughts/comments.
>
>
>
>
>
> Sent from my cell phone
>
> < dy>
>
>
>
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