Lars, <br>We looked into this and found some "threaded pop rivets" they were stainless steel and you had to buy the tool and then you just drill from the top, insert the pop rivet that leaves a threaded shaft facing skyward that you could attach L feet or other attachments to with a nut and washer....they guaranteed a waterproof connection and i imagine that you could always add some Eternabond double sided butyl tape to the bottoms of your L feet to double ensure the waterproof seal. They supplied engineering pullout documentation...you will need to provide them with the thickness of the purlins, the thickness of the metal roofing, and the thickness of the insulation if present for them to spec the right size rivet. <br>
<br>The company we found that had what seemed like it would work well was Bollhoff - a German company. They have US distribution so you can source the tool and materials domestically....<br>Good luck....<br><br>-- <br>Sunny Regards,<br>
Kirpal Khalsa<br>NABCEP Certified Solar PV Installer<br>Renewable Energy Systems<br><a href="http://www.oregonsolarworks.com">www.oregonsolarworks.com</a><br>541-218-0201 m<br>541-592-3958 o<br><br><br><div class="gmail_quote">
On Thu, Mar 15, 2012 at 9:40 AM, Allan Sindelar <span dir="ltr"><<a href="mailto:allan@positiveenergysolar.com">allan@positiveenergysolar.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<u></u>
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Lars,<br>
This has been addressed before on this list, but its been awhile.
#14 self-tapping ("Tek") screws have phenomenal pull-out strength in
standard steel purlins. My advice is to research this through your
fastener supplier; I have seen charts on pull-out strength of
various sizes and materials. I think you'll find that you can come
up with a screw attachment schedule with which you'll be satisfied.<br>
Allan<br>
<br>
<div>
<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com" target="_blank"><font color="#000099" face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font face="Times New Roman, Times, serif"><br>
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<br>
On 3/15/2012 10:26 AM, lars Ortegren wrote:
</div></div><blockquote type="cite"><div><div class="h5">
<div>
<p class="MsoNormal">Wrenches,<u></u><u></u></p>
<p class="MsoNormal">We have a project coming up where we are
installing a large array on a low slope metal building with
metal purlins. Typically we would through bolt our attachment
to the purlins, but in this case the building is a
self-storage, and access is not an option. Does anyone out
there have experience with any top side only metal-metal
attachments? I’ve thought about using some larger sized
stainless self-tapping screws, but I worry about the pull out
strength (as the roof combined with the c-channel purlins are
only about 1/8”) and the effects of heat and cooling of the
roof backing the screws out over time. Any thoughts ?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><b><i>Lars Ortegren<u></u><u></u></i></b></p>
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