sal wrote:

On Wed, 17 Nov 2004 22:49:52 -0600, "3D Peruna"
wrote:

===============Snip================

That's nice if you make these membranes, and I'm sure it's nice for
roofers working on the high-sloped mansions that are all the rage now
aday's, but it means SQUAT for the low-slope home owner that has to
deal with tearing the hell out of his decking in 20 years because of
friggin sticky-back membrane. (!)

The purpose of an I/W membrane is to keep out the ice dams which often GROW

from the bottom up. If you don't have the membrane adhered to the

substrate, the ice can grow between the substrate and the membrane, making
the whole thing useless. Even with proper drip flashing, this could be a
problem. With the adhered membrane, you can't get any water between it and
the substrate, thus making it an effective system. Nailing it down is as
effective as having felt.




Nope, common sense over rules here.

What common sense?


where the heck do you think the nails for the shingles go though? so
nailing down would not compromise I/W membrane.

The membrane is quite flexible and will seal around nails very nicely.
Just like having an o-ring.


the reason you have ice shield is so that the melted water penetrating
the roof surface (top layer of shingles) does not reach the decking.

Yep, you are with the program so far.


the ice would build up and when the snow/ice continues to melt, the
resulting water would never reach the top edge of the I/W, because of
the roofs' pitch. The ice dam that is there would also melt as the
melting snow. so the water would be carried away over the top of the
ice.

my guess again why its has an adhesive backing is. for the ultimate
protection. the manufactures doesn't give a rats ass about the guy
doing the reroof 20 to 40 years down the road.

The adhesive gives one more layer of protection by keeping any water
than happens to get under the shield from migrating between the membrane
and the roof sheathing.


you do not need to stick the **** down. the bond is not that good and
certainly not strong enough to stop the expansion of ice. which btw is
never the problem. the problem is ice on the surface not below the ice
shield.

If the bond isn't that good, then why are you complaining about the
tear-off of this stuff?


Matt