Weather-tightness
Weather-tightness is the ability of a building element to resist water ingress under wind-driven rain. AS 2047 sets the performance bar for external windows and doors.
Ask Chalkline about this →Weather-tightness is the capacity of an external building element (cladding, window, door, roof, junction, or penetration) to resist water ingress under wind-driven rain conditions. A weather-tight assembly keeps water on the outside of the building envelope without relying on sealant alone as the primary defence.
For external windows and glazed doors, AS 2047:2014 sets the water penetration resistance requirement: no water ingress through the assembly at a pressure equal to 30% of the positive Serviceability Limit State design wind pressure for the site (verified 2026-05-10). The test pressure is derived from the site’s wind classification under AS 4055.
Weather-tightness failures at residential scale are most commonly found at door thresholds (no sill pan flashing), window heads (no head flashing), and wall-to-roof junctions (inadequate sarking lap). These defects typically do not appear at practical completion but emerge in the first wet season, making them a common warranty claim.
Also known as: weathertightness, watertightness (in some contexts)
Category: Building envelope
Related
See also
- Flashing, the physical waterproofing detail that makes weather-tightness possible at junctions
- Tolerance
- NCC 2022 Vol 2 overview
Last updated: 2026-05-10. Verified: 2026-05-10.