Letter to the Editor

Question

Weathertightness requirements for garage doors

In the February 2007 edition of Codewords (Issue 018), in the article Weathertightness requirements for garages, you said that:

garage door-to-frame details are not included in E2/AS1 and must be considered separately. Such considerations would be limited to ensuring any leakage around garage doors does not result in damage (deterioration) to the garage or house, or dampness in the house.

Question: Does this mean that only the most weather-resistant garage doors should be used, or should we just screw garage doors shut to avoid them being left open?

Answer

The Building Code Clause E2.2 states 'Buildings shall be constructed to provide adequate resistance to... moisture from the outside.'  The performance requirement E2.3.2 requires (garage doors to) 'prevent the penetration of water that could cause undue dampness or damage to building elements'.

The word 'undue' is important here. Weathertightness for many situations does not need to be to the same levels required for health in habitable spaces.

Garage doors must be considered suitable for Building Code purposes if they adequately prevent moisture from deteriorating the surrounding framing (or if the framing has enough compensating durability) and any water that gets past the doors cannot migrate to places whereit could cause dampness or damage.

Under the Building Code, it wouldn't matter if a small amount of water splattered through a garage door onto the car or the floor of the garage in normal circumstances, as this would be unlikely to result in undue moisture for the garage.

As far as we are aware, most proprietary garage doors are capable of adequately meeting Building Code requirements in normal situations. However, in some special situations (for example, garages above habitable spaces), more careful weathertightness of the garage might need to be considered.

Weathertightness of garage doors is simply a question of what is appropriate. This is something designers must assess, and officials be satisfied of on reasonable grounds.