Any time i have to remove copings on a roof that have a plastic dpc under them the plastic is wet.This is normaly due to the plastic sweating,basicaly making your own leak! This is on free stone and concrete ones.
I had to remove new concrete copings on a party wall on one house which had a dpc under them.At the bottom where the angled coping met the one flat one the dpc was folded back on its self.In this fold was a puddle of water,and all up the dpc it was covered in condensating water.
Whats the point,i mean its not as if water is going to come through 2" of a concrete coping.Then you see the edge of the dpc under the coping on other jobs.
The water tracks across the top and UNDER the dpc when it runs off the coping.
I rip the the plastic off and then bed them on a water proof sand cement mix.I suspose the people who use this practice dont ever go back to find out it causes more trouble than its worth.
I had to remove new concrete copings on a party wall on one house which had a dpc under them.At the bottom where the angled coping met the one flat one the dpc was folded back on its self.In this fold was a puddle of water,and all up the dpc it was covered in condensating water.
Whats the point,i mean its not as if water is going to come through 2" of a concrete coping.Then you see the edge of the dpc under the coping on other jobs.
The water tracks across the top and UNDER the dpc when it runs off the coping.
I rip the the plastic off and then bed them on a water proof sand cement mix.I suspose the people who use this practice dont ever go back to find out it causes more trouble than its worth.