On Thu, 26 Apr 2007 20:53:46 -0500, "Don Young"
wrote:


"DJW" wrote in message
oups.com...
Ok I have read the directions on my Owens-Corning shingles. However
when I started to remove the existing old shingles I see they were
nailed in the tar seal strip. Now I am not sure if back 27 years ago
the installer had used nail guns. But the shingles are dried and very
bad but still I have no leaks.
Aside from the warranty being voided isn't this a good place to put
the nail for the following reasons?
1. The tar will seal around the nail shaft and the head after the sun
has done it's thing.
2. The sealing might stop the nail from popping up in the future.
3. The nail is a bit farther up from the above courses tab's lower
edge.
I am amazed that the nail is so close to the edge of the overlap
anyway when installed via the directions. I would think if anything
that the nail should go above the tar seal strip. That way any water
that might be pulled up under the shingle by capillary action would be
stopped by the seal of the two shingles before reaching the nail.
What do you think?

I think I do not know near as much about shingles and their proper
installation as does the manufacturer. I do agree that it is nice to know
why when there is something I do not understand. I am sure that the nailing
recommendations are based on leak and blow-off testing of different nailing
methods.

Don Young

A standard 3-tab is 18" by 36" with an 8" exposure, right?
That means that there's a 2" band to put a nail where it
will both penetrate the back edge of the shingle below,
and be covered by the shingle above. Within that
2" strip, I expect you want the nail as low as possible
so that there's less flap to blow around in the wind,
but back far enough that wind-driven water doesn't back up
under the shingle around the nail-head.