Hi, just at the early stages of an extension & was wondering if fitting a cavity wall drip tray had to be done above all openings like windows & doors & around the whole base of the extension. Cant seem to find good info on this. I was also wondering how you fit the cavity wall insulation to the tray.
if you use catnic boot lintols above all the openings then you don't need cavity trays as they are designed to work in the same fashion. As for the the need of it around the base, if its a concrete floor, you build the inner leaf to floor height,concrete the floor and leave the outer course lower, the dpm is then left to drape over the inner leaf to form a damp tray to the outer leaf
local council officers differ from each county, you need to check before commencement, they will need to check foundation depth before the concrete pour, once up to dpc height and the sub base laid and compacted they will tell you what they require.