Ceiling insulation

Dear Tom Gocze,
I have read your article on ceiling insulation in the past weekend paper. I
do have ceiling insulation (fiberglass). It looks fairly filled in between
the joists. The ceiling area does have electrical wiring in some areas. My
questions are: Does it make sense to put in sheet insulation? what
thickness of insulation? I'd also want to apply some sort of walkways for
possible use?
Several years ago, I took your advice on getting a on demand hot water
heater. I have been very pleased with it too.
Thanks,
John
Brewer, Maine

Hi John,
I would blow in some cellulose insulation on top of the fiberglass if you
need to add more. There should be about 16 inches up there.
Where you want to cover the insulation, an inch of polyisocyanurate
(urethane) foam replaces about 2 inches of fiberglass or cellulose.
Tom