On Tuesday, March 13, 2018 at 8:07:14 AM UTC-4, Robert11 wrote:
Hello,


How "necessary" or desirable is it to remove the old
shingles first ?


If you can afford it, rip it.
If the contractor can get a dumpster close rip it.


e.g., what "grade" of Shingles for up here in New England ?
I imagine most of the cost is the labor; right ?

Labor is the big part. Buy really nice shingles. A million people will be seeing them.


That Rubberized sheet I think the use as a matter of course:
How far back up the rood should it extend ? etc., etc. ?

If you are asking, it is because you plan on ripping the old off.
That is your weather/ice guard.


If the contractor shows you different shingle options, be certain to look at them outdoors. You inside light is likely not the same light.