Remedies: moisture

Weathertightness is a significant problems for art deco houses because of their flat roofs and parapet walls.


The flat or low-pitched roofs and parapet walls of art deco houses generally meant that they had poor protection against the ingress of rain, and weathertightness was a major problem.

Other factors contributing to weathertightness issues are: the lack of eaves and protection for window heads; tiny cracks forming in stucco cladding, allowing water in (see matching new to existing for details); and the lack of wall and roof underlay (see remedies: roofing and cladding for details). Cavities can be prone to condensation buildup without building paper and adequate cavity ventilation.

As well as carrying out remedial work to damage that may already have occurred, the issue of how the principles of E2/AS1 can be incorporated into the reconstruction must also be addressed during renovation work.
Issues to consider include:

  • the lack of eaves
  • the lack of protection at window heads
  • the existing cladding where it is stucco – stucco is only an acceptable solution under E2/AS1 on a cavity, and direct-fixed stucco will need to be consented as an Alternative Solution (see Complaince paths)
  • window detailing where an existing window has been removed or a new window is to be inserted into an existing wall
  • roof pitch – in many cases roofs are below the current minimum slope requirements
  • internal gutter size, as it may not meet current Building Code requirements
  • the lack of a wall and roof underlay.

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Internal moisture

Older houses tend to be draughtier and therefore less energy efficient, but they are also less prone to internal moisture problems than newer, more airtight houses because air movement occurs continuously through gaps around windows and doors, chimneys and floorboards.

As a house becomes more airtight, particularly with the installation of insulation and aluminimum glazing, internal moisture generated from cooking, washing, unflued gas heaters and clothes dryers, could become a problem. Internally-generated moisture problems can generally be identified by stale indoor odours.

Internal moisture problems may also be caused by:

If there is a musty smell, it is likely to occur from one of these sources of moisture.

If the problem is from an internal moisture source, options available to remove internal moisture include to:

  • install extract fans in the kitchen and the bathroom that are ducted to outside
  • install insulation where possible to keep indoor temperatures higher
  • install security catches to windows that allow ventilation without providing a security risk
  • install new windows with trickle ventilators.

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Other problems


See Common problems and remedies Roofing and cladding.


Rot is common when moisture is present, and can cause significant structural damage. Read more.


Mould is common when moisture is present, and can be harmful to health. Read more.