On Mon, 22 Nov 2004 02:24:55 -0500, thunder
scribbled this interesting note:

Not exactly true. That plastic strip also happens to be the nail line, at
least in three tabs.

One reason to nail where the manufacturer says is so you are nailing
not only through the shingle you are currently working with, but also
through the top of the shingle below it-think of it as a kind of
double protection. Another reason is that if wind does get under a
shingle, you want the nails as low as you can get them and still have
them water proof since the more surface area the wind can grab the
more likely it is to remove a shingle for you.

The plastic strips serve no other purpose than the keep the shingles
from sticking together while packaged up. No other reason at all.
None. I've never seen any statement from any shingle manufacturer
we've worked with in over twenty five years of working with roofing
materials that says otherwise.

Of course I could be mistaken, just sharing what I've seen while on
the job, while reading web sites, what I've seen in warranty
statements, etc.
--
John Willis
(Remove the Primes before e-mailing me)