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How to Keep Rainwater From Running Under a Garage Door

News   Brett Rowley  | 22 March 2021

A garage door that does not seal properly can cause a host of issues. Just like you would not want moisture to leak into your home, you should also want a dry garage. You might not sleep in your garage, but it’s more than likely keeping several valuable possessions, as well as your car, safe from the elements. 

With Perth’s winter coming soon and bringing with it turbulent weather conditions such as strong gusts of wind and sheets of rain, you want to ensure you’re garage is as prepared as your home to fight the elements. That’s why we break down the possible causes and solutions for rainwater running under your garage door.

Why Should I Care About Keeping Moisture from Leaking Under My Garage Door?

Your garage is an extension of your home, and you should therefore treat it as such! The issue comes in that many garages do not keep the elements out properly. But the good news is that we have a handful of tips and ideas on how to seal your garage door from the rain.

It’s never pleasant to enter your garage and find the unpleasant surprise that rainwater has pooled on the floor. Not only can this lead to cracks in your garage structure and water damage to your possessions stored in the garage, but it can also cause health issues.

For example, constant dampness can lead to the formation of mould. This, in turn, could lead to diseases and just a foul smell filling your garage. Not to mention that someone could get injured if they slip on a wet garage floor! 

First Things First: Are You Sure The Moisture is Rain? 

If there is constant moisture in your garage, it could be due to condensation. This ‘sweat’ occurs when warm air is in contact with cold temperatures. And because garage floors and walls are often made from concrete, this is a frequent occurrence. 

Sometimes referred to as ‘sweating slab syndrome’, you can usually diagnose it by looking at the floor. Does it look darker due to moisture absorbed in the concrete?

Another tell-tale that your garage floor is sweating is that it leaves white minerals behind. Alternatively, you can tape a piece of plastic to the area and compare the covered concrete to the rest after a day or two. 

What Should I Do if My Floor is ‘Sweating’?

If your floor is sweating, you should consider decreasing the humidity with a dehumidifier or switch up the garage floor with something other than concrete.

Good options to look at include garage floor tiles or vinyl mats as they will adapt to the rest of the garage’s temperature. If all else fails, you have to consider that your garage door not sealing could be the culprit for rainwater running under it.

A Quick Hack: How Can I Tell That My Garage Door Is Not Sealed Properly?

A surefire way to know that your garage door does not seal is to check if any daylight is seeping through at the bottom and around your garage door. Several things can damage a garage door’s seals, including general wear and tear over time or changes to the driveway’s construction itself.

Troubleshooting: Possible Causes and Solutions for Rainwater Running under Your Garage Door 

Roof Problems

When your roof has no gutters around your garage area, it could be the cause of rainwater accumulating and going under your garage door.

Solution: Install Gutters

This might be a bit more of a pricy solution, but you will be thankful that you decided to install gutters around your garage. It will, therefore, transfer instead of collect the rainwater. 

Your Driveway Pitch

If you drive down your driveway instead of up, the decline can cause rainwater to pool around your garage building. 

Solution: Trench Drains

Trench drain garage doors rainwater

Although you have to clear these trench drains from time to time, they can be a real lifesaver in waterproofing your garage door. You install these drains right in front of your garage doors, allowing rainwater to drain instead of collect. 

The Garage is Drafty, or Door is Leaking 

If you notice that your garage door is leaking water or it’s drafty even when the garage door is closed, you might need new weatherstrips.

These strips are usually made from vinyl or rubber and fill the gaps between your garage roller door panels, acting as a garage door water barrier. 

Solution: Replace Worn-Out Weatherstrips

The weatherstrips or weather seals act as a garage door wind and water barrier. Self-adhesive strips, you can easily stick them on yourself to either the bottom or the top of each garage door panel.

Rainwater is Pooling on the Floor

A faulty or missing threshold seal could be to blame, causing the water to come through from under the garage door.

Solution: Install or Replace Garage Door Threshold Seals 

Consider replacing or installing garage threshold seals to seal your garage door further. This acts as a garage door bottom seal and is made of hard rubber or aluminium, and you can stick it straight onto the floor where it meets your garage floor. It acts as a kind of ‘speedbump’ to prevent water from entering under your door.

It will also help with regulating the indoor temperature to avoid condensation. This door sealing solution is not too expensive and is quick and easy to install. 


In conclusion, once you have isolated the cause of rainwater coming through under your garage door or experiencing excessive condensation, you now know how to fix it. The best solution of all, of course, is to ensure that you have a high-quality, functional garage door. 

Contact us if you are ready to get a new garage door, so the next time Perth winter arrives, you have 100% peace of mind that your garage is sealed from the elements. 

Brett Rowley

Brett is a garage door expert who also runs Gryphon Garage Doors. He strives for great customer service, excellent product knowledge and constant innovation.

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