<div dir="ltr">A couple of years ago, we had a tornado in Minneapolis. A few hours later, after the storm had long since passed, and ten miles away, a storm door crashed down in someone's backyard, intact. </div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Tue, Jan 14, 2014 at 1:31 PM, RT <span dir="ltr"><<a href="mailto:archilogic@yahoo.ca" target="_blank">archilogic@yahoo.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Reuben wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
figured [double-walled polycarbonate] would lighter, easier to fasten,<br>
consistent across the full length (5 equal patio doors)<br>
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BC John wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I worry about non laminated glass as tempered can still cut<br>
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Clark wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
the first one was torn-off by ice 10 years ago.battens holding the glass down were cedar 5/4 x 3<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
The main roof is 7.5/12 (aka 10/16, the golden mean) steel, allowing the ice to slide,that time taking my panels with it.<br>
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Reuben mentioned initially that the porch roof would be 35 ft in length.<br>
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The IGUs from three, six-ft wide patio doors would yield 12 sheets of glass, nominal coverage 12 x 3' = 36 ft.<br>
(The actual width of the glass would be ~ 34", spaced 1.5" between edges of the glass ( {[1/2" bearing + 1/4" expansion clearance for each sheet] x2} + 1" batten bearing surface = 2.5" batten<br>
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The above bearing/batten details would be the same regardless of whether the panels were glass or plast-ecchhh!.<br>
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One of course can use the store-bought extruded aluminum glazing bars, clamping bars and batten caps but for residential apps, the cost can be prohibitive not to mentioned needlessly high in embodied-energy costs.<br>
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Wood is fine for all of the above components so long as it is detailed to anticipate and deal with water.<br>
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ie It used to be that the local building supply would carry metal studs and track made from galvalume stock.<br>
The track for 2.5" studs could be modified slightly so that it would do nicely as snap-on weather-proof caps for 2.5" wide wooden clamping bars (aka battens) which could either be pre-painted if desired or left au naturel. The modification consists of bending a small lip onto the legs (at one of edge-stiffening creases already formed into the channel by the stud manufacturer) so that it would catch the edge of a rebate milled into the edge of the wooden batten, the rebate designed to function as a caulking allowance.<br>
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I prefer to custom-bend the batten covers from strips cut from sheet stock intended for exterior use and mill bevelled-edge wooden battens, slightly narrower than 2.5" at the top face).<br>
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No exposed fasteners and no rough surfaces to catch/hold snow or ice.<br>
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*<br>
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I think that the concerns about being cut by non-laminated tempered glass are unwarranted.<br>
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Plain tempered glass is virtually indestructable. Pretty much the only way that it can be broken is if the edge receives a sharp impact (which includes being pressed up against the shank of a metal fastener due to insufficient edge clearance (including expansion allowance) being provided.<br>
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I've had door panels that were temporarily leaned up against a porch, picked up by winds and thrown a few metres landing face-first on some large blast rock (ie sharp edges) without breaking more than a few times. It was easy to see where the rock impacted the face of the glass because the boulders left a streak of abraded stone dust across the face of the glass (which washed off).<br>
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I think that it was last year I mentioned on this list where I reported that ice & snow accumulations on a almost zero-slope sheet of 3 ft wide tempered glass on a walkway canopy, glass supported only along the longitudinal edges had deflected 1.5 inches at the midspan of the unsupported 3 ft width under the weight of the couple of feets-deep re-frozen snow/snow melt ... without breaking. I've had people tell me that cows have walked across their sheets of tempered patio door glass without breaking it.<br>
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In the unlikely event that tempered patio door glass does break, it will break by exploding into a gazillion little harmless ~ 1/4" chunks ... not as large dangerous shards as would be the case with untempered glass.<br>
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Pretty much the only way to get cut is if one laid down nekkid in a pile of the chunks and purposely ground one's flesh into the glass chunks.<br>
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I'd venture that laminated glass would be more hazardous because it'd come down en masse, all of the broken mass being held together by the plast-ecchhh! sheet laminate so while one may not get cut by pieces of falling glass, one would get a pretty good bump on the head being hit by a 60 pound mass o' glass.<br>
*<br>
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And an off-topic "heads up" to listmembers who eat chicken nuggets and have small dogs:<br>
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<a href="http://www.youtube.com/watch?v=_ym0rxisOpw" target="_blank">http://www.youtube.com/watch?<u></u>v=_ym0rxisOpw</a><br>
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-- <br>
=== * ===<br>
Rob Tom AOD257<br>
Kanata, Ontario, Canada<br>
<br>
< A r c h i L o g i c at Y a h o o dot c a ><br>
(manually winnow the chaff from my edress if you hit "reply")<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><br><br>b e n j a m i n p r a t t<br> <br>professor art+design<br>the university of wisconsin stout
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