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<DIV><FONT size=4>As noted by my earlier message, I was advocating predrilling
2x furring strips to achieve accurate alignment of long screws through thick
layer of foam that could reliably hit the intermittent studs. I had the
issue of hitting the rafters through 3” foam and .5” paneling installed under
existing sheetrock of cathedral ceiling. However, on the exterior of my
house that had 5/8” textured plywood siding, I did not need to be accurate
because the plywood had sufficient grip. I could run GKR screws anywhere
and it would grip suffieciently to allow the head to countersink into the
exterior furring strip. In the house I am designing, we are planning on
putting all the insulation on the outside, 6” or 8” EPS, still to be
determined. I am wanting to know if the withdrawal strength of
.5” plywood or osb would be sufficient. I like the simplicity of
assembling a very solid conventional sheathing enclosed framed structure.
</FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><FONT size=4>Because this is a new structure, I am planning on setting the
EPS and the 2x furring strip directly on metal termite shield, insect barrier,
flashing that is in direct contact with the foundation. In so doing, the
fasteners are no longer fully supporting the weight of the 2x furring and the
selected siding. Fasteners would only be resisting horizontal loads from
wind or vibrations. 2x4 studs commonly get away with 4 16d nails.
Fasteners for furring could be located at band joist, top plates or other
horizontal framing, allowing more location tolerances and avoiding the need to
predrill. </FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><FONT style="FONT-SIZE: 13.6pt">All insulation in exterior mounted foam
makes the structural sheathing over the conventional 2x4 framing on the interior
side of the thermal envelope. Can some on the list point me to issues relating
to outgassing in plywoods and oriented stranded boards? I expect to
achieve near passiv haus level of tightness. We will install ERV for
ventilation. </FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><FONT size=4>Also, we are considering alternative bracing to rely on the
EPS for the exterior sheathing. In this approach, there is not tendency
for foam to sag from weight. Then we would have to achieve accuracy and
predrilling would be appropriate. Also detailing the bracing becomes more
important. However, it would save a whole layer of sheathing from project
cost. </FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><FONT size=4>Still probing for more knowledge and insights from this
list. It is exciting to be moving forward in achieving a new level of
performance. Your help is very appreciated. </FONT></DIV>
<DIV><FONT size=4></FONT> </DIV>
<DIV><FONT size=4>Eli </FONT></DIV>
<DIV><FONT size=4><A
href="http://www.conservationarchitect.net">www.conservationarchitect.net</A>
</FONT></DIV>
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<DIV style="font-color: black"><B>From:</B> <A title=jfstraube@gmail.com
href="mailto:jfstraube@gmail.com">John Straube</A> </DIV>
<DIV><B>Sent:</B> Tuesday, November 20, 2012 5:12 PM</DIV>
<DIV><B>To:</B> <A title=greenbuilding@lists.bioenergylists.org
href="mailto:greenbuilding@lists.bioenergylists.org">Green Building</A> </DIV>
<DIV><B>Cc:</B> <A title=chris@koehn.com href="mailto:chris@koehn.com">Chris
Koehn</A> </DIV>
<DIV><B>Subject:</B> Re: [Greenbuilding] Insulation fasteners</DIV></DIV></DIV>
<DIV> </DIV></DIV>
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<DIV class=moz-cite-prefix><FONT
face="Helvetica, Arial,
sans-serif">Thats an interesting idea
Chris! never seen it done, but it sounds really worth it for 2nd stories
etc. <BR><BR></FONT>
<DIV class=moz-signature>Dr John Straube, P.Eng. <BR><A
class=moz-txt-link-abbreviated
href="http://www.BuildingScience.com">www.BuildingScience.com</A></DIV>On
12-11-20 3:47 PM, Chris Koehn wrote:<BR></DIV>
<BLOCKQUOTE cite=mid:F0FDCCCF-4763-44E0-9E8C-154424271824@koehn.com type="cite"><PRE wrap="">For thick insulation, take the time to pre-drill before installing. If the structure is accurately framed, studs are at predictable centres, and it's much easier to drill straight holes when the sheet is on horses than when you're standing on a ladder. We snap lines and pre-install the screws, which makes running them in while working at height a much simpler process. As well, choosing a screw that self-taps into existing (and often hard) materials makes life easier.
Best,
Chris Koehn
TimberGuides
Vancouver Island
Eli wrote: "I know from experience there is a lot of labor from missing the stud and
trying again, as well as creating additional holes to the the thermal
barrier. The thicker the insulation gets, the more difficult it becomes to
hit the stud with hand held drills."
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