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Why Box Gutter Design is Important

Box Gutter

Take a quick look at any building and it should be easy enough to spot the gutters lining the edges. Look for a little longer and a complete rainwater system with gutters, downpipes, rainheads and perhaps even a rainwater tank will all be revealed.

However, not all gutters are the same. Box gutters are slightly different from the norm. Box gutters, also known as internal gutters, are roof drainage system that sits directly above a roof, rather than hanging over the sides.

This design can lead to some issues, despite the practicality. That’s why box gutter design is so important. It has to match up to Australian standards to keep your home safe from damaging leaks.

Here’s why well designed box gutters are so important to you and your property.

What Makes Box Gutters Different?

Ultimately, box gutters and traditional eaves gutters perform the same function of efficient roof drainage. The only quirks are a few standout features differentiating box gutters from standard gutters.

Traditional gutters are designed to sit on the perimeter of a roof. Therefore, any overflow hopefully still ends up draining away from a house or at worst leaks into the eaves. Box gutters don’t have the same luxury.

As the same suggests, box gutters have a flat base and are shaped like a square box. Sometimes they’re also called an internal gutter or perhaps a concealed gutter. The name also alludes to the fact the gutter is often boxed into the middle of a roof.

Common locations for a box gutter include the meeting point of two roof valleys, or behind a parapet or elevated fascia board. They’re also found on properties where there’s limited space for standard gutters due to tight boundaries or council requirements.

As the box gutter sits on top of a home, any overflow will pose an immediate problem to the roof and ceiling. Water cannot just drain over the edge and fall into the garden.

So if rainwater levels quickly rose, how can a house with box gutters installed cope? Easy. Box gutters must have an additional overflow provision in the form of a rainhead or sump.

Okay, What are Rainheads and Sumps?

Rainheads are probably more recognisable than most people think. A rainhead or sump is a metal container on the side of a building, located between the gutter and downpipe. It helps to funnel water away from the roof safely as an external overflow point.

They come in a wide range of shapes and colours and are usually pretty discreet.

Sumps are slightly different from rainheads, too. Sump design is just like a square or rectangular box where stormwater is collected to minimise build-up in the gutter itself.


Does Every Box Gutter Require a Rainhead?

Box gutters have a tendency to overflow easily. Leaves and debris can easily block them. And the worst part is a leaky internal gutter can be a nightmare.

According to the Australian National Construction Code, box gutter design “must be able to cope with a 5 minute duration rainfall intensity and a 1 in 100 year average recurrence interval, rather than 1 in 20 as is the case for eave gutters.”

In translation, the rainhead is an overflow provision to safely funnel excess water into the downpipe. It has to be installed so the gutter system can cope with high capacity rainfall at all times.

Appropriate gutter design means the roof drainage system will not compromise the integrity of a home.

Is There Any Change to Gutter Maintenance?

Nope, maintenance is the same as eaves gutters. Although, it never hurts to stay regular. And it remains the perfect solution to overflowing box gutters.

The tendency for additional debris build-up means you should always keep an eye on your roof. If you know a storm is coming and you have the time, check the box gutter! Even after heavy rain or a big storm, clean out the gutters so when the next storm hits there’ll be a clear path and unimpeded water flow.

Regular gutter cleaning also keeps box gutters healthier for longer. Tannin found within many leaves is released as they break down. Leave them for too long and the tannic acid build-up can rust box gutters. That’s not good for your home because any holes in the gutter will be located right above your head. And water will only go to one place – the ceiling.

That’s why clean gutters are incredibly beneficial. Stormwater will always be directed towards the outlet and rainhead, where overflow will be safely funnelled into the stormwater system. Roofs remain pristine and box gutters stay strong for years with good regular maintenance.