[RE-wrenches] Mounting L feet on corrugated metal roof.

[Ken Schaal]

Hi John

When you say ' corrugated ---with flat spans  and ribs-- do you mean what is generally called Grand Rib around here in Va. 8" flat panel with a low 1" wide area in the middle of the flat panel, then a rib 1"+ high, held on to the roof sheathing with hex head screws and sealing washers?

If so, we just did a job like that and used ' Peel and Stick ' membrane cut to make pads under the L feet, predrilled for the 5/16" x 3" lags into as many truss top chords or rafters we could hit--the ribs sometimes intervene, in which case we use 3/8 2" lags-- with a healthy dollup of black silicone in the hole and under the L feet. When the silicone squeezes out from under the foot, I always smooth it out with a finger, especially on the uphill side to better shed water and avoid an area where freeze- thaw can degrade the bond to the roof. Be sure the metal in clean before application. The silicone should squeeze out of the hole as the lag goes in, and any silicone on your finger is applied to the head of the lag, but that is more a place to get rid of it than a permanent water barrier.

If it's true sinusoidal corrogated about 5 years ago we mounted a thermal panel by making custom feet that spanned two peaks with a EPDM rubber gasket under the foot where the  screws penetrated, one into each peak. Hard to hit rafters, so decking type , thickness, decking fasterner type and schedule, metal thickness, and L foot screw diameter are all important factors, dependent on your wind and snow loads. 

How will you handle the expansion /contraction issue ?

I've used this general method for 30 years, starting with thermal panels.
There will probably be other suggestions as well. More than one way, so long as compounds are compatible.

Ken @ CommonWealth Solar
  ----- Original Message ----- 
  From: cvsolar at aol.com 
  To: re-wrenches at lists.re-wrenches.org 
  Sent: Friday, November 26, 2010 8:55 AM
  Subject: [RE-wrenches] Mounting L feet on corrugated metal roof.


  Wrenches,
       Do you have any tips, stories, methods for mounting L feet on the corrugated metal roof that has short flat spans and ribs.
  After all these years, I am facing my first install on this kind of roof.  We originally were going to install 6 top of pole mounts but he decided the neighbors would not like the appearance so now we are looking at a 20 x 40' metal roof on the garage.  The customer asked about flashing the L feet.  I'm at a loss to figure out how to do that. 

  John Blittersdorf
  Central Vermont Solar & Wind
  Rutland, VT 05701
  cvsolar at aol.com


   





------------------------------------------------------------------------------


  _______________________________________________
  List sponsored by Home Power magazine

  List Address: RE-wrenches at lists.re-wrenches.org

  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




------------------------------------------------------------------------------



  No virus found in this incoming message.
  Checked by AVG - www.avg.com 
  Version: 9.0.872 / Virus Database: 271.1.1/3281 - Release Date: 11/26/10 02:34:00
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20101126/8385dbc7/attachment-0003.html>