Lars, 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.
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.... Good luck.... -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o On Thu, Mar 15, 2012 at 9:40 AM, Allan Sindelar < [email protected]> wrote: > ** > Lars, > 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. > Allan > > *Allan Sindelar* > *[email protected]* <[email protected]> > NABCEP Certified Photovoltaic Installer > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > *Positive Energy, Inc.* > 3201 Calle Marie > Santa Fe, New Mexico 87507 > *505 424-1112* > *www.positiveenergysolar.com* <http://www.positiveenergysolar.com/>**** > > ***************** > * > > > On 3/15/2012 10:26 AM, lars Ortegren wrote: > > Wrenches,**** > > 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 ?**** > > ** ** > > *Lars Ortegren* > > ** ** > > Director of Operations**** > > California Solar Electric Company**** > > 10141 Evening Star Drive, Suite 6**** > > Grass Valley, CA 95945**** > > http://www.californiasolarco.com/**** > > ** ** > > Phone : (530)274-3671**** > > Fax: (530)274-7518**** > > ** ** > > *California C-10 Electical Contractor #779624* > > *NABCEP Certified PV Installer # 091110-89* > > *Certified NABCEP Continuing Education Provider* > > More about NABCEP:**** > > ** ** > > http://www.nabcep.org/**** > > ** ** > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & > settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out participant bios:www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > >
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