How long should shingles last?

[buckscrape]

I have a home around 12 years old, how long should the original shingles last before needing replacement?

[nutherblond]

from Reader's Digest March 2007 issue article written by Tom Philbin (I just read this last night)...Normally, an asphalt shingle roof lasts 15 to 20 years. You need to replace the roof if you see curling or missing shingles or a large amount of granular material from the shingles collecting in gutters.

If you happen to see this issue read the article. It's titled '5 Biggest Home Repair Rip-Offs'.