<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Nov 26, 2016 at 9:42 AM, Michael O'Brien <span dir="ltr"><<a href="mailto:obrien@hevanet.com" target="_blank">obrien@hevanet.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div>Hi, Reuben--</div><div id="gmail-m_7113498976693558370AppleMailSignature"><br></div><div id="gmail-m_7113498976693558370AppleMailSignature">I think some metal roofing has high reflectance and emissivity, would reduce the heat in the attic. I wonder if a foil sheet stapled to the bottom of the rafters would add more reflectance, </div></div></blockquote><div>When you say 'bottom of rafters' can you explain? Are you saying staple the foil sheet to the inside faces of the purlins - which would then touch the back side of the drywall? <br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div id="gmail-m_7113498976693558370AppleMailSignature">not sure of your configuration.<br></div></div></blockquote><div>standing seam painted metal roof -> tar paper -> 5/8 plywood -> 2x6 rafters +insulation batt -> 2x4 purlins (horizontal)+insulation batt -> sheet rock -> prime+ paint <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div id="gmail-m_7113498976693558370AppleMailSignature"><br>Best, Mike<div>Sent from my iPhone</div></div><div><div class="gmail-h5"><div><br>On Nov 26, 2016, at 7:20 AM, Reuben Deumling <<a href="mailto:9watts@gmail.com" target="_blank">9watts@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Thanks for your reply, Topher, and good to hear from you. This list is not quite what it once was... Have folks drifted elsewhere, and if so I wonder where those places might be?<br><br><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Nov 26, 2016 at 7:03 AM, Topher Belknap <span dir="ltr"><<a href="mailto:topher@greenfret.com" target="_blank">topher@greenfret.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
Greetings,<br>
<br>
Thermal losses should be considered on the basis of surface area, not<br>
volume. </blockquote><div>Agreed.<br> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Heat stratification (for good or ill) is pretty insignificant in a modern, well insulated and sealed house. </blockquote><div>I've noticed this myself and tried to discuss this with the heating man who came to advise/make a bid for the additional duct work to the new upstairs rooms), but I don't think I was able to persuade him. <br> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Venting ought to be the same for either option (if I am envisioning correctly). Since it should<br>
run up the outer surface, not the interior. </blockquote><div>I am aware that standard practice has me installing vent channels between the insulation-in-the-rafter-bays and the sheathing, that connect vents at the bottom to ridge vents--we've discussed this here over the years--but I also think I remember folks arguing that in certain situations one could skip those channels. Am I misremembering this or just experiencing wishful thinking? I confess that getting the venting right seems to me the biggest challenge at the moment. <br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">My concern would be ensuring that the vapor barrier (if your climate wants one) is put in<br>
the right place. </blockquote><div>Ah, vapor barriers. I'd love advice on this. There is currently a layer of roofing felt on the outside of the sheathing. The batts of insulation I'm planning on using for the walls and sloped roof sections of the envelope are paper-faced fiberglass. I was going to rip the paper off the batts that run vertical and keep it on the inner layer that runs horizontal. Is that a viable approach?<br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">If you decide on the flat ceiling, fill that space with insulation.<br></blockquote><div>I was certainly planning on insulating above the horizontal sheet rock, but are you suggesting filling the entire triangle? <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
Thank you kindly.<br>
<br>
Topher<br>
<br>
--<br>
Topher Belknap<br>
Green Fret Consulting<br>
Kermit didn't know the half of it...<br>
<a href="http://www.GreenFret.com/" rel="noreferrer" target="_blank">http://www.GreenFret.com/</a><br>
<br>
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