Damp Proofing

Parapet wall build

Anonymous user 23/02/2024 - 3.30 PM

Hi all, I'm in the process of building a single story side extension with parapet walls on 3 sides. The parapet wall will be built at say 1 block above the (epdm) flat roof. My 2 questions are if I continue the epdm sheeting vertical up the 2 or 3 courses of the parapet wall and incorperate it directly under the coping stone (40mm in) would this be sufficient enough for me not to need a parapet cavity tray or is it regulations to insert one? I am using brick on the outer wall with a 100mm full fill insulation cavity then solid breeze blocks on the inner skin, I already have a cavity tray at ground dpc. As far as I know i have to close the cavity using slate then lay out a sheet of dpc before bedding the coping stones on top. My second question is if I had to use a parapet cavity tray, when it comes to putting a hole in both skins for a wall drain pipe into a hopper would the cavity tray have to sit below the wall drain pipe or would it go through the cavity tray and be sealed? I hope you can understand my questions. Thanks all. Stay safe