Why Are My Gutters Overflowing? Please Help Me!

Overflowing gutters can be caused by a number of different reasons from a blocked downpipe to not enough downpipes being installed. Read further to identify why your gutters might be overflowing and what to do about it.

Signs that your gutters are overflowing

Signs that your gutters are overflowing back into your roof

One of the most common sign that you gutters are overflowing are stained roof eaves such as in the video above.

Reasons why your gutters are overflowing and how to fix them

An overflowing gutter is a common problem that many homeowners have experienced in the past, though not to worry – I’m here to help! Below are known reasons and how to fix it.

1. Blocked gutters

A gutter full of leaves

One of the most common causes is when leaves or debris enter your gutters. Over time leaves and debris builds up and cause blockages in your guttering system stopping water from freely flowing down your roof, into your gutters, and out of your downpipes.

Debris blocking up the bottom of a roof valley
Another example of debris blocked at the bottom of the valley where the water runs into the gutter

Believe it or not, another common cause of blocked gutters is bird nests, yes – you heard me right – bird nests! You would be surprised how many gutters I’ve had to unblock because of family of birds have decided to make a gutter their home.

A bird nest near a gutter
A bird nest I recently had to relocate

How to fix blocked gutters

If blocked gutters are your issue, then you’ll need to remove the leaves and/or debris to ensure rainwater escapes properly and your gutters don’t overflow.

Cleaning gutters before a storm

Use a professional to clean your gutters…

Note, as cleaning out your gutters can be a dangerous job, especially if you need to get up onto the roof recommendation is to contact your local gutter cleaning business to do it for you.


Alternatively, if you’re keen to fix it yourself here are a few steps you can:

  1. Using a small single-hand leaf blower go along the gutter with a ladder, blowing out all the leaves and debris (Note, if possible do this on a dry day).

    When you’re doing ensure you pay special attention to where the valleys run into the gutter as it’s important that the water must be able to flow freely from the valley into the gutter.

    Also, another important area to focus on is where the downpipes join the gutter if this is blocked rainwater will not be able to escape the gutter and run down the downpipe;

  2. Once all the large leaves or debris are cleared out you can then use a hose to go along and wash out the remaining dirt and moss etc that might be caked onto the bottom of the gutter.

If you would rather avoid blowing out the leaves and debris onto your yard then an alternative approach is to go along with a ladder and bucket, removing the blockages by hand (make sure you wear some heavy-duty gloves).

How to prevent your gutters from getting blocked

The best way to prevent your gutters from getting blocked is to install gutter guard. Coming in different styles and sizes to suit your roof, gutter guard is essentially a type of mesh that sits over your gutter (usually between the roof and the gutter) preventing any leaves or debris from entering your gutter.

2. Gutters are too small

In some instances, you’ll find that the gutters that have been installed are simply too small to handle the rainfall. This means that in heavy downfalls, the gutters don’t have the capacity in them to hold all the rain before it has the chance to disperse via the downpipes.

I’ve seen this happen often when patios are installed in Australia and instead of replacing adjoining gutters with proper box gutters, the patio installers just run all the rain from the patio into the existing roof gutters which do not have the capacity to handle both the rainfall from the patio and the rainfall from the roof.

If this is the issue then you have a couple of options to consider.

Option 1: Replace with a bigger gutter

One way to address this issue is to look at removing the existing gutter and replacing it with a larger capacity gutter such as a ‘box gutter’.

Alternatively, you may get away with adding more downpipes to the area of guttering as a workaround though your best bet would be to upgrade to a gutter with a larger capacity.

Option 2: Add more downpipes

A cheaper option and hopefully less effort (although you made need to add another soakwell) is to add an additional downpipe to the gutter that is deemed too small, allowing the water to disperse quicker from the gutter.

Option 3: Add a gutter overflow spout

What is an overflow spout you may ask? A gutter overflow spout is an outlet that is mounted halfway up the face of the gutter. If the gutter is filling up quickly and can’t disperse quick enough via the downpipes, as the water rises it flows out of the gutter spout and onto the ground below instead.

What option would I recommend?

If you don’t mind water flowing out onto the ground below in heavy downpours then out of the options above, the cheapest and probably quickest option to go with option 3 – install a gutter overflow spout. These are only a couple of dollars at Bunnings or Stratco and are a great way to ensure water can escape your gutters without backflowing into your eaves.

However, before going down this path, if you are unsure it’s always best to seek advice from your local roof plumber who can do a proper assessment of the issue and run through the options with you.

See also: Gutter Overflow Spout

3. Gutters do not run toward downpipes

Sometimes you’ll find that when a gutter has been installed, it’s been installed with a slight run-off away from the downpipe, rather than towards it. When it pours down with rain the water gathers in the gutter with no quick escape and rather than flowing towards the downpipe and leaving it builds up and overflows.

What do I do if my gutters do not run towards the downpipe?

If this is your issue, then unfortunately it’s not a quick fix as you need to take the gutter off and fix it higher on the furthest end from the downpipe to ensure the gutter is at least level or has a slight fall toward the downpipe.

Alternatively, if this is not an option then you could consider adding another downpipe, or a gutter overflow spout at the end where the water is pooling to allow the water to exist there.

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