How to Keep Water Out of a Garage

If your house is like mine, it’s common to get puddles of water pooling on your garage floor.

In my garage, that puddle seems to always be in the front right corner and it drives me CRAZY.

Water rushing in the front of my garage

Like most homes, my is sloped to direct all of the water to the corners. There was supposed to be a drainage outlet there to help it flow outside.

There isn’t.

Now I’m on a mission to get as much water out of my garage as possible.

I started digging into where the water came from, and some ways to stop it.

Assuming you don’t have flood damage or a leaky hot tub in your garage, water accumulates in two main ways: dripping off your car or rainwater coming in under your garage door.

I’ll talk about each of those situations separately. Then we’ll cover what you can do to minimize or even eliminate the amount of excess water in your garage.

If water is coming in through your concrete walls, check out my article showing my process how to waterproof garage walls to stop water from leaking in.

Why does my garage door leak?

There are several reasons why water gets into your garage.

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Almost all of them have water coming in through that big gaping hole that you drive your car through.

So why does a garage door leak? It depends where the leak is coming from. Leaks around the sides of the door usually mean that a seal is damaged or missing. Awnings or sills stop water from getting behind the door, so if you see leaking at the top of the door, that’s usually the culprit. Water coming in at the bottom of the door usually has to do with gaps between the concrete floor and the garage door.

The most common place where your garage door leaks is right at the bottom: where the door meets the concrete floor.

Let’s look at a couple of different ways to fix those leaks: a threshold seal and a trench drain.

What is a garage door threshold seal?

Over time, concrete floors shift and settle, creating gaps where the garage door doesn’t fit properly.

If there are gaps, then it’s like a flashing neon sign pointing the way into your garage. That’s where a garage threshold seal can help.

A garage threshold seal is a piece of hard rubber, plastic or aluminum that sticks on the concrete right where the door meets the concrete floor – almost like a small speed bump. It creates a tighter seal by eliminating any gaps which helps to regulate the temperature inside your garage, as well as keep bugs, dust and rainwater outside where they belong.

Why do you need one?

How a garage door threshold seal works.

I said in the beginning that my concrete floor isn’t exactly level. In fact, there’s a gap of about an inch between the bottom of the garage door’s rubber seal and the concrete floor.

That’s big enough for cockroaches or even small rodents to get through.

Just imagine how much water could seep in.

A threshold seal virtually eliminates that gap by adding a barrier underneath and also behind the garage door seal.

Seals are fairly inexpensive (under $100) and can easily be installed in under an hour.

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Do you need a trench drain?

If your driveway slopes into your garage then just adding seals around the door won’t fix the problem.

The water is just going to run down the slope straight into your garage.

A trench drain (channel drain) right outside the garage door fixes that. It catches the water running down the slope and then ‘channels’ it away from the door to someplace where you have adequate drainage.

Trench drains can prevent water in your garage.

Imagine a long U-shaped tub made out of metal or plastic that’s open on top. Cover that opening with a metal grate to keep out any leaves and debris.

One or both of the open ends need to be attached to drainage pipes, so the water can drain out.

Trench drains are harder to install than some of the other solutions here.

You’ll either need to pull up the pavers or jackhammer your driveway to make room. Once the drain is in, you’ll then need to add new concrete to keep it in place.

Personally, I’d skip a trench drain unless you’ve got a badly sloped driveway that causes lots of water runoff into your garage.

Should you put a wet car in the garage?

The car’s finish is designed to withstand extremes, so I wouldn’t worry about the water damaging the paint beyond unsightly water spots.

The dirty, salty slush that you’ve got in the Northeast is a different story.

Unless you really hate your car, it’s best to clean that off before it damages your paint and the snow melts all over your garage floor.

That doesn’t mean you’re all clear though. There’s not much air flow in your garage, which is why we need alternative ways to keep your garage cool.

No air flow means the water on your car can find it’s way in the cracks and in between the panels of your car can’t properly evaporate. If the seals are old and damaged, that water may then seep into more critical areas.

That excess water also adds to the overall humidity level in the garage. There’s a story that placing a bowl of water in a perfectly sealed room will increase the humidity level to 100%. It turns out that’s true.

This is especially a problem if you live in the hot and humid South.

High humidity can also cause electrical problems – not just for your car, but for your cordless tools, fans and anything else with wiring that’s not sealed well.

So should you put a wet car in the garage? No. It’s best to always dry your car off once you park it for the night.

How do I dry out my garage?

Eventually, you’re going to have puddles of water in your garage that you need to get rid of.

At best, it’ll be rainwater dripping from your car or blowing in from the outside. Worst case it could be a drainage problem or a flood. Flooding is just a bit beyond the scope of this article, but for smaller leaks, let’s talk about a few quick ways that you can dry out your garage.

Squeegee out the excess water: Don’t let that water pool. The longer water sits, the more damage it will do – especially if it can seep into your walls or drywall.

Run a dehumidifier: A garage dehumidifier will take the water out of the air. It’s a slow process that uses a lot of energy so don’t rely on this too much unless you’re a stockholder in your local electric company.

Use a fan to get more air circulation: The more airflow you have, the faster your garage will dry out. I have a wall-mounted Air King fan in my garage and I love it!

Towels and mops: The low-tech method of drying out your garage isn’t necessarily a bad one. If your leak is bad enough, put towels in between the water and anything sensitive. Try to mop up any excess water before it has time to spread.

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Tim Wells

Tim Wells, the founder of Garage Transformed, has been featured in dozens of home renovation publications, including, Home Stratosphere, House Digest, Livingetc, and SFGate. Since 2018, he has helped over two million people transform their everyday garages into something they can be proud of. He lives in Central Florida with his wife and bulldog.