Comments inserted as well. Tony wrote:Wrong. You are
apparently not familiar with ice dams at all. Felt does
absolutely ziltch for protection against ice dams, you must use a water &
ice guard which is manufactured under several names.

Sounds like you work for W.R.Grace, a major supplier of bituminous membrane.
Being from Michigan, I'm _very_ familiar with ice dams, and with the latest and
greatest of ice and water shield technology. A double coverage of 30 lb. felt
installed up only 3 feet beyond the inside wall will stop an ice dam from
penetrating the decking perfectly well, and cost less than the modified bitumin
(tar).
Yeah, don't use felt if you want the back of the tar strip to
stick to the
decking. Felt is layed for a purpose other than a dry in feature as you
suggest.

I suggest you look at a shingle to see if there even IS a tar strip on the
backside. Felt is laid just for the reasons I stated. Hope this helps. Tom
Someday, it'll all be over....