Windows – water entry around sashes

Where it is suspected that there may be more leaks in the building, engaging a registered building surveyor with experience in leaky homes is strongly recommended. This is particularly the case for houses built from the mid-1990s to the late-2000s. DIY repairs and repairs by non-specialist builders often do not solve the problem and may result in further problems. See our Weathertight guide for more details.

Causes

Defective putty or degraded seals

Water blown in around poorly fitted sash

External head and/or jamb flashing failure

Leaking at junctions between cladding and window

Common

Cause

Defective putty or degraded seals

Repair

  • replace defective putty (in timber windows) following the guidance here
  • replace seals on aluminium windows following the guidance here

Cause

Water blown in around poorly fitted sash

Repair

  • call a builder to re-fit or replace the sash

Cause

External head and/or jamb flashing failure

Repair

  • where a problem is found with flashings on just one window, call a well-experienced licensed builder to replace the flashing and investigate whether water has entered framing timber around the window. If the leak has occurred within 15 years of the original construction, the house has not met Building Code durability requirements, and building work to repair the leak requires a building consent

  • where the problem is widespread around the house, engage a registered building surveyor to investigate

Cause

Leaking at junctions between cladding and window

Repair

  • engage a registered building surveyor to investigate