New Zealand · metal roofing
Extra High flashing cover
Extra High is Category B at every pitch: 200 mm ridge, 100 mm barge, two upstands.
Sheet count usually stays the same when the wind zone changes. What changes is flashing cover and edge fixing. This takeoff treats NZS 3604 Extra High as CoP 8.4 Category B at every pitch. Category A, the residential default, is 130 mm ridge and 75 mm barge.
Very High and a pitch under 10° is also Category B on this page. SED is out of scope. Low, Medium and High at a normal pitch stay Category A, so they do not get their own checker.
Write EH on the order, and the flashing type as Category B, even when the sheets look the same as a Medium-zone roof. Fixing pattern and edge zones still come from the current manufacturer sheet.
FAQ
Does Extra High change the sheet count?
Not by itself. Cover width and the ridge-direction measurement still set the count. Extra High changes ridge and barge cover, and the upstand count.
What about Very High?
Very High is Category B here only when the pitch is under 10°. At 10° and above it stays Category A. Extra High is Category B at every pitch.