Building a New Home Check Your Gutter Overflows Mechanisms

Building a New Home Check Your Gutter Overflows Mechanisms

1 Why?
What happens in really heavy downpours of rain when the volume of water is so great that the gutters and down pipes just cannot cope? If the issue is not managed correctly, water could flow back into the home across the eaves lining and cause considerable damage!

So the “why” in this equation is that we need to have mechanisms which ensures surplus water hitting the gutters and down pipes is not diverted back into the building. The Building Code of Australia has some specific requirements to ensure that “Overflow mechanisms” are installed into gutters to ensure that water cannot flow back into the home.

2 What?
An overflow mechanism is basically a design of the gutter which will direct water away from the building in heavy downpours so that it cannot flow back into the building. There are several options which can be implemented to achieve this outcome.
The simplest solution is to simply ensure that the front of the gutter (outer edge) is lower than the back of the gutter (edge adjacent to fascia/building) so that when the gutter if full, the water will simply spill over the front of the gutter.

Another common alternative solution is slotted gutters which enable an overflow of water to once again spill out of the gutter as opposed to flowing back into the home. The issue with both solutions is the aesthetic look of both solutions may detract from the appearance of the home. High fronted gutters are popular among home owners and builders as they hide the lower edge of tiles or roof cladding. Similarly, some builders/owners simply do not like the look of slotted gutters. So the bottom line is appearance over important functional requirements.

3 Where?
There is a surprising amount of science and calculation required in designing and planning for the correct gutters and downpipes sizes and the associated overflow mechanisms. Importantly, calculations need to be undertaken for each home in its specific location. These calculations will help determine the required volume of gutters, downpipes and overflow mechanisms. All of these calculations will be undertaken by your builder when planning the construction of your home.

4 How
There are a variety of options open to builders when planning how to install overflow mechanisms into the guttering of your home. See

5 Summary
1. In heavy rains gutters can fill quickly, requiring that surplus water needs to be redirected away from the home.
2. If gutter overflow mechanisms are not installed, there is the potential that surplus water will travel back across the eaves lining into the wall cavities and or onto the ceiling of the property. Water ingress of this nature can cause considerable damage.
3. The current Building Code of Australia requires new gutters to be installed with water overflow mechanisms so that water cannot flow back into the home.
4. When building a new home, you should check that water overflow mechanisms have been installed by your builder.
5. Houspect Building inspectors check that water overflow mechanisms have been installed when undertaking construction inspections on behalf of clients.

Call Houspect WA to organise your new home construction inspection. Houspect can inspect your home at the Practical Completion Stage or at every key stage along the construction journey.

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