It’s a 15 year old roof with an architectural type shingle. The built up areas are not another layer of shingle it’s just more granules on the shingle.
The question is, the built up areas only have cracks, is this a concern? It didn’t look like the cracks went below the depth of the top layer, but it’s hard to tell.
A picture of the ridge cap shows how the built up are is cracked but not the original layer.
Visible cracks in any shingle is time for replacement.
Were there many cracks or just a few?
I’ve seen 12 year old Architectural shingles fail. Many early failures are manufacturer defects, and others are due to improper ventilation or multiple layered.
Had the same cracking on the same type of shingle on a house about 10 years old, I was very concerned. Just so happened…the rep for those shingles was in town that day and I asked him to have a look at them. He told us that this was **normal **for these type of shingles (25-30 year) and not to worry about it. No performance problem. I think the brand was IKO.
This is more like etching to me. Just one of the downfalls to the crossover shingles. Won’t make it leak, but makes it look ugly. Really it’s better to use regular architectural shingles to eliminate the water runs at places like valleys, downspout exits and other areas where water tends to sidetrack. They have some pretty colors though. Atlas also makes one called chalet. Seems like all crossovers tend to blister and etch on the thicker portions. Sometimes they will crack all the way thru when your installing them on steep ridges when it’s cold.