<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body ><div>John,</div><div>I did not mention the air, water and vapor barrier the metal roofing contractor spec'ed on top of the plywood, under the metal...titanium psi-30 I think it is called.</div><div>The fastening system is typical staggered hidden clips for the male side of the panel that the femail side of the next panel snaps over.</div><div>Why Epson over polyiso?</div><div>Thanks</div><div><br></div>Sent from my cell phone<div></div><br><br>-------- Original message --------<br>From: John Salmen <terrain@shaw.ca> <br>Date:12/07/2014 1:03 PM (GMT-05:00) <br>To: 'Green Building' <greenbuilding@lists.bioenergylists.org> <br>Cc: <br>Subject: Re: [Greenbuilding] Polyiso strength on roof <br><br><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">John<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Greenbuilding [mailto:greenbuilding-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Ron Cascio<br><b>Sent:</b> December-07-14 9:45 AM<br><b>To:</b> 'Green Building'<br><b>Subject:</b> Re: [Greenbuilding] Polyiso strength on roof<o:p></o:p></span></p></div></div><p class="MsoNormal"><o:p> </o:p></p><p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Sounds good to me.<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Ron<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Greenbuilding [<a href="mailto:greenbuilding-bounces@lists.bioenergylists.org">mailto:greenbuilding-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Bill Allen<br><b>Sent:</b> Sunday, December 07, 2014 10:52 AM<br><b>To:</b> Green Building<br><b>Subject:</b> [Greenbuilding] Polyiso strength on roof<o:p></o:p></span></p></div></div><p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p><div><p class="MsoNormal"><span lang="EN-US">Hi all<o:p></o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US">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).<o:p></o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US">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.<o:p></o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US">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.<o:p></o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US">Thanks for any thoughts/comments.<o:p></o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p></div><div><p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p></div><p class="MsoNormal"><span lang="EN-US">Sent from my cell phone<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US">< dy><o:p></o:p></span></p></div></body></html>