Joe wrote:Think about it - peel-and-stick underside, granular coated top side
-
both serve basically ONE purpose - to prevent the roofer from sliping
and falling off the roof. Neither the adhesive underside or the
granular coated top side help AT ALL in helping the membrane perform
it's function of preventing water that gets under the shingles from
making contact with the wood deck.

However, both the peel-and-stick bottom side and
granular/asphalt-coated top side are a MAJOR pain when it comes to
re-roofing.

Comments?
Correct, Joe. Only for the relative safety of the roofer (Which I thought I'd
covered in my original reply to the OP, BTW). The membrane doesn't NEED to be
stuck down to the deck to perform it's function, but only to the drip edge and
any neighboring pieces of i&w shield. You can get away with a 3 inch lap. And
yes, it's hell to tear off old i&w shield. Tom
Work at your leisure!