Weathertightness Print

Design Outcome

The house is dry, weathertight and easy to maintain

​​​​Building weathertightness will generally be addressed by complying with the Building Code, but can also be dependant on a suitably skilled and experienced construction team. 

However, some forms and materials carry a higher risk than others and may be linked with greater costs in order meet Building Code standards. Decisions made at the beginning of the design process can save cost later. 

The design of the house should consider weathertightness, ease of maintenance and the durability of materials at the start of the process. Weathertightness risks are greater when: 

  • Buildings have a high number of complex wall junctions and a range of materials. 
  • Buildings have upper level decks, particularl​y within the building footprint of the floor below, and internal gutters.


Design for weathertightness is not about stifling innovation or creating boring buildings. It is about being aware of weathertightness at the beginning of the design process and designing out potential weaknesses. 

A good designer will know how to balance the requirements of creating a weathertight building with creating one that is attractive and well articulated.

Better Design Practice

Keep it simple. Simpler building forms will be easier to weatherproof than complex ones.
Minimising the amount of material changes, complex junctions, joins and flashings will also make the house cheaper to make weathertight.

Protect from the weather. 
The easiest way to keep the water out is to stop it from getting in. Eaves are a simple and effective way of protecting the walls and roof junctions. 

Choose materials carefully. 
The ease of maintaining the outside of a building will have a direct impact on how it performs over its lifetime. Some cladding systems rely on more onerous or costly maintenance regimes to ensure they stay weathertight. A cladding system that is easy to maintain will look better over time, do a better job of protecting the house and cost less. 

Consider the ‘Four D’s’ when designing a house: 
  • Deflection – keeping the water away from potential entry points 
  • Drainage – removing any water that does enter 
  • Drying – allowing any remaining moisture to be removed by ventilation or diffusion 
  • Durability – providing durable low maintenance materials.

Rules of Thumb

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