On Wed, 05 Jan 2005 04:37:49 GMT, Tony Hwang
scribbled this interesting note:

Hi,
I'd remove old shingles to inspect underneath.(why put on extra weight
on the roof keeping old layer?; lazy man's job)
Install new flashings,

Why install all new flashings? The assumption you seem to be making is
that all the existing flashings are bad. They may not be. 30 year old
lead plumbing vent flashings are actually of better quality than
similar flashings you can buy today, and far superior to any of the
cheap flashings with neoprene seals that are commonly used now.
Furnace and water heater flashings commonly rust out and require
replacement, to be sure, but not all roof jacks and vents necessarily
need to be replaced simply because a new roof is being installed.

One item that needs to be addressed, no matter who performs the work,
is that wherever a plane of a roof meets a wall or chimney, that area
will have the proper flashing and counter flashing installed. Far too
often installers choose to merely tar in these trouble spots with no
effort given to doing the job correctly. In these instances leaks
develop anytime between immediately and six months to a year.
Skylights are another area that never accept any less than a correctly
done installation and proper care must be taken to keep you, the
homeowner, happy and content!


--
John Willis
(Remove the Primes before e-mailing me)