Slotted Gutters: What Are Gutter Overflow Slots And How Do They Work?

So you’ve heard about slotted gutters (or gutters with holes in them) and you’re not sure what they’re about or whether to install them? 

Not to worry, to help you make a decision I’ve put together an article all about slotted gutters in Australia to help.

Quarter round slotted colorbond gutters in Australia

What are slotted gutters and what are their benefits?

In Australia, Slotted gutters are a type of gutter that has slots in the front of the gutter that prevent rainwater from overflowing back into your eaves or your home’s roof space.

How you may ask?  If your outlets are blocked or if there is heavy rainfall, your gutters can quickly fill up and without nowhere to go the rainwater will rise and overflow into your eaves.  

With slots in the front of your gutter, as the rainwater rises, it then escapes out through the slots of your gutter instead of rising and overflowing over the back of the gutters.

As the water flows out through the slots it will then fall to the ground directly underneath.

Why can you buy slotted gutters?

I’ve found that most of the large hardware stores in Australia such as Bunnings or Mitre10 won’t stock slotted gutters, hence if you are looking to purchase these you’re best bet is to go to a roof plumbing manufacturer such as Fielders or Stratco where they can make slotted gutters specific to your requirements.

Slotted gutter profiles

Slotted colourbond gutters in Australia
An example of slotted quarter round

Slotted gutters are available in a number of different profiles with most roofing manufacturers being able to provide their different profiles with either slotted or unslotted versions.  Profiles that come with slots include, but are not limited to:

  • Quarter-round and half-round gutters
  • Wide-based or square gutters
  • Fascia gutters

What colours do slotted gutters come in?

Colorbond gutter with water overflow slots
An example of slotted gutter in the colorbond colour of surfmist

When it comes to colours, slotted gutters are usually offered in the same colourbond colours that standard gutters come in.

colourbond colours
Example of colorbond colour chart

However, your roofing supplier will be able to confirm this during the ordering process.

Disadvantages of slotted gutters

There are not a lot of disadvantages to slotted gutters, though here are a couple that I’ve come across:

1. Not as aesthetically pleasing

Personally, I find that all the slots in the face of the gutter don’t look as aesthetically pleasing as good as non-slotted gutters.

2. No control of excess water

When water escapes out of the slots the water just runs down the face of the gutter and hits the ground below which can be an issue if you have slotted gutters installed over an area you hope to keep dry such as an outdoor patio.

3. Watermarks or rust stains on the face of the gutter

Although not a common issue, I have noticed that some of the older gutters with slots start to show signs of surface rust and watermarking around the gutter slots.  

However, I believe this is more for gutters that have a constant issue of gutters overflowing where the water is continually flowing out of the slots and running down the face of thrle gutter in heavy rainfall.

Where not to use slotted gutters

As I mentioned above, as you can’t control the flow of excess water I would look at avoiding the installation of slotted gutters around areas such as outdoor patios as the water could overflow and drip down into your patio area.  

If you do have a patio then perhaps look at a box gutter or a non-slotted gutter with overflow spouts on either side of your patio.

Would I use slotted gutters?

I often get asked this question and my recommendation is that you need to ensure you have a way for water to escape if your gutters start to overflow, hence you can either opt for slotted gutters or overflow spouts.

Personally, I prefer the use of overflow spouts as I feel that non-slotted gutters look better and with overflow spouts you can direct the water better.  However, saying this, if you don’t mind the slots then slotted gutters are still a great option.

Final thoughts

I hope you found this article helpful and that you now have the information you require to make a decision regarding slotted gutters.  

Regardless of whether or not you chose slotted gutters, please ensure that you consider overflow management and that you choose either slotted gutters or the installation of overflow spouts to avoid damage to your eaves or even worse, your property’s roof space.

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