Hello,

Live outside of Boston.

Know there are a zillion variables involved, as well as brand and quality
level, but what is a typical
lifespan for roof shingles on a residence (when they should be replaced) ?

Assume the quality level of these original shingles was probably "average,"
undoubtedly not the best,
or heaviest, available at the time (some 25 yrs ago).

Thanks,
Bob