Hi George,

On a pitched roof, my understanding is that the rubber underlayment
should go down first, then the drip edge. I'd have thought that the
drip should go first: then, any water captured by the membrane would run
off over the drip. I can guess that putting the membrane first lets the
it seal the drip nails. But, to what end, if there's no place for the
water to go?

When I shingled our roofs, I installed the drip edge along the bottom of
the slope first, then installed my roofing felt over the top. This way if
water finds it's way under the shingles, in theory it should flow down on
top of the felt, then over the drip edge. If the drip edge were on top of
the felt, the water would go under the drip edge to the wood decking. I
don't see why membrane would be any different.

On the sides of the roof slope, I installed the drip edge after installing
the felt. This keeps any rain that may be blown under the edge of the
shingles on top of the felt, and not blown under the felt to the wood.

On top of the drip edge at the bottom.

Under the drip edge on the sides.

Take care,

Anthony