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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>On the bracing. Sheathing as part of a shear wall is probably the simplest, effective and cost effective way of bracing. It also forms one layer of weather resistance protecting the structure.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You don’t however need to sheath a whole building – just those portions identified as providing shear structure for the building. Depending on the building this could be a 1/3 of the exterior walls. The problem though is if some future resident wants to put a big window in a shear wall...<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Quite a while ago I researched cross strapping (flat strap x bracing) for lateral strength and did not emerge with a warm fuzzy feeling of confidence. To cross brace effectively you really need to design for it well from foundation connections through to top plate – which becomes the equivalent of designing shear walls into a structure. At that point it is more cost effective to simply sheath a 6 or 8 ft section of wall as a shear wall as the ply cost will be less than cost of strapping and gussets. Getting an engineer to design a shear wall is cheap in comparison to a moment frame (like getting a fancy chef to make a hamburger)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Now my Japanese framing manual is very thorough on wood bracing and gives me a higher level of confidence (mostly aesthetic). Unfortunately we can’t afford to spend that kind of time on structural, though it would be nice.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>On the outgassing. Prior to good availability of NAUF (no added urea formaldehyde) plywoods we typically used exterior rated plywood in interiors as it primarily used phenolic formaldehyde adhesives which were more water resistant. They are more stable therefore are not as prone to outgassing and are considered ‘acceptable’ for very low levels of emissions in comparison to conventional interior plywoods. I ordered my first lift load of no formaldehyde cabinet ply 30 years ago but it became increasingly difficult to obtain in following decades. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Basically most ‘domestic’ plywood uses phenolic adhesives at this point and all exterior plywood and composite boards use phenolic adhesives or some equivalent water resistant glues that meet or are exempted from most emissions standards. As for standards they used to be voluntary but we now have what I call the OBAMA standard (he signed it) which is a law and has resulted in the NAUF designation which unfortunately doesn’t cover all products – so most of it is still voluntary. We also have californa CARB regulations pushing manufacturers.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You do have to be extremely careful in what you purchase from any yard as we are being dumped on with low quality (unfortunately mostly Chinese) products. Home depot is especially bad for unregulated products that are not domestic and not subject to any requirements and can’t be researched. Prior to purchasing from a local supplier I get the name of the mill and then get an msds or product sheet from the mill – even mills are importing and then putting their own name on the product (the woods are thick with thieves)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You can actually eliminate fasteners from the foam and the furring strips using foam adhesive and I think you will get better performance under wind loading (the bond strength of a foam adhesive – wood to foam in a squiggle pattern or on 16” centers would exceed screws. Similarly the bond of a glued 1x3 furring spaced 16 or 24” to foam would meet the loading criteria of the heaviest siding. Foam will not sag or creep unless subjected to loads of over 50% of its compressive strength (about 700lbs per square foot). Figure out the siding load, adhesive bond area and go from there for spacing of furring. Occasional screw or nail to hold things in place while the foam glue sets. I am a traditional carpenter and love fasteners but also traditional enough to want to eliminate them when not needed.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";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";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> Greenbuilding [mailto:greenbuilding-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Eli Talking<br><b>Sent:</b> November-28-12 6:48 AM<br><b>To:</b> jfstraube@gmail.com; Green Building<br><b>Cc:</b> Chris Koehn<br><b>Subject:</b> [Greenbuilding] Outgassing of Sheathing & Insulation fasteners<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><div><p class=MsoNormal><span style='font-size:13.5pt'>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. </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>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. </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>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. </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>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. </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>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. </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>Eli </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'><a href="http://www.conservationarchitect.net">www.conservationarchitect.net</a> </span><span style='font-size:14.0pt'><o:p></o:p></span></p></div><div><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <o:p></o:p></span></p></div><div><div><p class=MsoNormal style='background:whitesmoke'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:jfstraube@gmail.com" title="jfstraube@gmail.com">John Straube</a> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:whitesmoke'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Sent:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Tuesday, November 20, 2012 5:12 PM<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:whitesmoke'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>To:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:greenbuilding@lists.bioenergylists.org" title="greenbuilding@lists.bioenergylists.org">Green Building</a> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:whitesmoke'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Cc:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:chris@koehn.com" title="chris@koehn.com">Chris Koehn</a> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:whitesmoke'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Subject:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Re: [Greenbuilding] Insulation fasteners<o:p></o:p></span></p></div></div></div><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p></div></div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-family:"Helvetica","sans-serif"'>Thats an interesting idea Chris! never seen it done, but it sounds really worth it for 2nd stories etc. </span><span style='font-family:"Calibri","sans-serif"'><o:p></o:p></span></p><div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Dr John Straube, P.Eng. <br><a href="http://www.BuildingScience.com">www.BuildingScience.com</a><o:p></o:p></span></p></div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>On 12-11-20 3:47 PM, Chris Koehn wrote:<o:p></o:p></span></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><pre>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.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Best,<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Chris Koehn<o:p></o:p></pre><pre>TimberGuides<o:p></o:p></pre><pre>Vancouver Island<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Eli wrote: "I know from experience there is a lot of labor from missing the stud and <o:p></o:p></pre><pre>trying again, as well as creating additional holes to the the thermal <o:p></o:p></pre><pre>barrier. The thicker the insulation gets, the more difficult it becomes to <o:p></o:p></pre><pre>hit the stud with hand held drills."<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>Greenbuilding mailing list<o:p></o:p></pre><pre>to Send a Message to the list, use the email address<o:p></o:p></pre><pre><a href="mailto:Greenbuilding@bioenergylists.org">Greenbuilding@bioenergylists.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>to UNSUBSCRIBE or Change your List Settings use the web page<o:p></o:p></pre><pre><a href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre></blockquote><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><div class=MsoNormal align=center style='text-align:center'><span style='font-family:"Calibri","sans-serif"'><hr size=2 width="100%" align=center></span></div><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>_______________________________________________<br>Greenbuilding mailing list<br>to Send a Message to the list, use the email address<br><a href="mailto:Greenbuilding@bioenergylists.org">Greenbuilding@bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org</a><o:p></o:p></span></p></div></div></div></div></body></html>