We use a stainless fender washer between the lag and L foot both to
prevent a galvanic reaction between the aluminum and zinc plating, and
to seal over the slot in the L foot. It also increases the strength to
prevent the lag from tearing through the L foot in a heavy wind load.
When we tighten it down, we always make sure that we have sealant coming
out on all sides of the L foot, and the washer. We've also used lags
with rubber sealing washers too.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 4/16/2014 9:52 AM, [email protected] wrote:
As Ray Walters wrote, L feet installed with the correct sealant have
lasted as long as the comp roofs they're
on.
As can be seen in the attached pictures of L-feet on a roof that I
will soon be repairing, the wrong sealant eventually shrinks and
separates from the L-foot. Also the slotted hole where the lag
penetrates is exposed. That's why flashings are used-- to cover up
sealant that won't last.
Thanks for all the pointers to better sealants.
Don Barch
Energy Solar
Ray Walters <[email protected] <mailto:[email protected]>> wrote:
....If I'm putting a 2 inch hole through a roof, then that
constitutes
a penetration, and using a flashing is usually a good idea. But when
I'm filling a 1/4" hole with a 5/16" lag, its really much closer to
being a roofing attachment than a penetration.
BTW, we're not just depending on some adhesive to stop the
moisture. An L foot is really a 1/4" thick aluminum flashing. It has
at least 4 sq in. of surface area held permanently in place by a
mechanical fastener that is applying a significant amount of downward
pressure.
..... L feet installed
with the correct sealant have lasted as long as the comp roofs
they're
on, 30 + years.
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