Jim:
Regarding comp roofing: In the past, the mantra has been "surface
area." The concept was to have as much flat surface of a mounting foot as
possible in contact with the roofing. This surface to surface contact area
was filled completely with the highest quality sealant we could find and
never did we have a leak. We satisfied this with a 3"X3" angle foot.
As I get older, I have moved towards improved roof attachments. We used to
simply put aluminum feet directly on comp roofing, but we have not done
this for the last year or so. In an era when we have more and more sub-par
competition, it seems counter intuitive to increase installation costs, but
the more I learn the more I feel compelled to avoid liability.
Fast forward to today: For comp roofs, we have used the Thompson
technologies Flatjack http://www.thompsontec.com/products/flatjack.html and
we are pretty enthusiastic about them. Also, we are more likely to use a
DPW Power post flashed with an Oatey flashing. On flat roofs we have
developed a technique of using an Oatey with an overlayment. On flat tile
roofs we are 100% DPW Power Post and Oatey wide base flashings. For barrel
tile, we use a wide based malleable aluminum flashing over the Power Posts.
There are posts out there that have only one lag hole, but the DPW holds
two lags. Speaking of lags, we used to use standard lags, now we use
exclusively Simpson hot dip 1/4 X 3 rated lags.
The bottom line is we can only sell our installation services to customers
that can appreciate an emphasis on quality. It means we miss a lot of
quotes, but I'm not willing to risk insurance claims.
I hope this answers your questions.
William Miller
At 08:40 AM 1/23/2009, you wrote:
Wrenches
I know this issue has been pretty well hashed over on this site but I see
a trend that I'm not sure how to relate to. The number of roof mounted PV
structure mfgrs is on the rise and many are migrating to the US market
from elsewhere.
The trend now seems to be to drill thru the 3-tab shingles, tiles etc and
into a rafter. Then drive home a threaded lag bolt with a patch of sealant
on the exposed surface and covered by a large flat metal washer. Of course
most all the mfgrs will offer an optional flashed version of attachment.
So has the technology of sealants improved to a point that only a dollop
is needed or is this just an adaptation of a European product coming here
with hopes that it will work in this market as well as it does there.
And how much of new products is simply cutting costs by reducing the
amount of materials needed.
Thanks as always
Jim Duncan
North Texas Renewable Energy Inc
817.917.0527
<mailto:nt...@earthlink.net>nt...@earthlink.net
www.ntrei.com
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