Phisherman wrote:

Having just one and only one layer is best. Shingles are heavy and
can put extra stress on a roof. I've seen some really bad sagging
roofs with 2,3 and 4 layers of shingles on it.


I've been scratching my head, wondering how much difference another
layer of shingles would
make. Google knows ) Found a website that seems to explain it well:
http://www.firesafedwellings.org/roo...of_weight.html

As for making a claim against the previous owner, that seems like it
would be a huge waste
in attorneys fees. Unless the roof caves in. I haven't read a
disclosure in a long time, but
if the previous owner had concealed anything, it seems the new owner
wouldn't yet know about the
layers of roofing. If there are really three layers of shingles, it
probably is far from a hidden
issue. Should be obvious from the street.