Flashing Supplement

For many years, Build magazine has been providing comprehensive advice on the design and installation of flashings in buildings. The best of those articles have been compiled in this Build supplement to provide a valuable reference for designers, builders and building officials.

Topics include

Flashings
Flashing Supplement
Last updated 19 May 2026
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Flashings play a vital role in preventing external moisture from getting through the building envelope (called primary defence) and ensuring that any moisture that does get in can drain out again (called secondary defence). Flashings are defined in New Zealand Building Code

Flashings are defined in New Zealand Building Code clause E2 External moisture as ‘component[s] formed from a rigid or flexible waterproof material that drains or deflects water back outside the cladding system’.

Required in many locations

Flashings are typically required at:

  • roof junctions and edges such as barges and gutters
  • changes in roof pitch such as ridges and hips
  • roof and wall penetrations such as windows, doors, meter boxes, skylights, flues and pipes
  • roof/wall intersections such as soffits, parapets and balustrades
  • vertical and horizontal junctions between cladding materials
  • intersections between different building elements.

This 96 page flashing is broken in to an overview, roof flashings, wall flashings and roof/wall intersections.

For the full Flashing supplement, see Build-162-Flashings-Supplement-S.pdf