Hi,
My builder has recently completed a large flat roof with fake pitched crown using EPDM, but instead of using lead lined drainage channels with 150mm high edges as per the architect's spec, they've used several layers of EPDM rubber, on a very shallow fall, with a small sheet of lead flashing at the end. The layers have been applied to protect the edges/rear of the crown (which was screwed on after the flat roof deck was covered), but unfortunately the thickness of each layer also impedes the drainage slightly.
Now we've just had heavy rain showers, I can see water is starting to pond in and around these drainage channels and in some the floor of the gully/channel seems to have collapsed completely leading to 1cm deep puddles of water collecting in the middle of drainage channels. We also have signs of damp on the inside of the internal leaf cavity wall below the drainage channels.
Is EPDM a suitable material for gullies like this, and if so should it be laid like this and with no real support underneath the channels? What would the correct detailing be? Is there a simple fix?
Finally the builder has mentioned putting stone chippings on the rubber. I was under the impression this wasn't necessary and might even increase chances if damaging the rubber?
View media item 67630 View media item 67631
My builder has recently completed a large flat roof with fake pitched crown using EPDM, but instead of using lead lined drainage channels with 150mm high edges as per the architect's spec, they've used several layers of EPDM rubber, on a very shallow fall, with a small sheet of lead flashing at the end. The layers have been applied to protect the edges/rear of the crown (which was screwed on after the flat roof deck was covered), but unfortunately the thickness of each layer also impedes the drainage slightly.
Now we've just had heavy rain showers, I can see water is starting to pond in and around these drainage channels and in some the floor of the gully/channel seems to have collapsed completely leading to 1cm deep puddles of water collecting in the middle of drainage channels. We also have signs of damp on the inside of the internal leaf cavity wall below the drainage channels.
Is EPDM a suitable material for gullies like this, and if so should it be laid like this and with no real support underneath the channels? What would the correct detailing be? Is there a simple fix?
Finally the builder has mentioned putting stone chippings on the rubber. I was under the impression this wasn't necessary and might even increase chances if damaging the rubber?
View media item 67630 View media item 67631
