Ridge Cap Shingle Technique Proper?


Hi,
I have a 12 year old asphalt shingle roof in an area in California with periodic high winds. Recently I noticed pieces of ridge cap shingles appearing in my driveway after a windy period of a few days. I went up on the roof and found the roof to be in excellent shape but the ridge cap shingles falling apart.
Replacing the ridge cap shingles is usually no big deal and there are plenty of good guides out there written by authors such as Mike Guertin.
On this roof, however, the original roofer made the roof cap from layers of stacked shingles four thick. I.e. where you would normally place a single shingle a stack of four is in place. This gives an interesting visual effect that's sort of oriental in appearance.
Here's the question, however. To keep these thick shingle "stacks" in place the roofer used exposed nails all along the ridge. I.e every 4 inches or so is a roofing nail (no doubt necessary to keep them from blowing off). We get very high heat here in the summer (110+) so the adhesive on the tiles should bond nicely. Normally the nails are hidden below the overlaying shingle and you don't have any exposed nails until the very end of the ridge. To which you normally apply roofing sealer. Not so here, all the nails are exposed. No sign of sealer.
Now, that said, the ridge has never leaked. Is there a trick in the fact that you are nailing through 5 shingles (4 in the new layer and one below)? Is this proper roofing technique? I do like the effect and could replace it just as it was originally installed. I wouldn't want to perpetuate a bad practice, however.
I could really use an opinion from someone more experienced than I. My total experience is one 2000' sq ft. house which was originally wood shingle. We converted it to asphalt with the guidance of an experienced contractor friend.
--jhujsak
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On Mar 11, 7:19 pm, snipped-for-privacy@gmail.com wrote:

The exposed nails are short roofing nails which probably do not go all the way through the stack of 4 shingles you describe. That is why no cement was required. The first layer of shingles which actually protect your roof was not punctured. The other layers were just nailed to each other since they are only decorative. The shingles overlap so that also holds them down. That's just a guess on my part.
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On Mar 11, 7:19 pm, snipped-for-privacy@gmail.com wrote:

The exposed nails are short roofing nails which probably do not go all the way through the stack of 4 shingles you describe. That is why no cement was required. The first layer of shingles which actually protect your roof was not punctured. The other layers were just nailed to each other since they are only decorative. The shingles overlap so that also holds them down. That's just a guess on my part.
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snipped-for-privacy@gmail.com wrote:

The additional shingles may act as an additional water barrier, or there may be a concealed layer of Ice & Water Shield (or approved equal) that is the real water barrier. There is so little water hitting six inches down form the peak that it's unlikely it would leak even if there was only one cap shingle. That's what I would do - insert a self-sealing membrane under the cap shingles to keep the water from hitting the wood. With the membrane I wouldn't worry at all.
My question for you: how is the roof ventilated? Is there a ridge vent?
R
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