Why Does My Garage Floor Sweat

My dad and I were talking on the phone the other day. He lives in Florida and I am out here in Arizona. He was giving me the rundown on a few projects he has been working on, and he was saying he was having some issues with his garage floor sweating. I had never experienced that living out here in the desert. So, the conversation left me wondering, why would a garage floor sweat? I did some research, and here is what I found. 

Condensation is formed on the garage floor when moist warm air comes in contact with the cool concrete. The moist air is cooled and loses its capacity to hold water vapor. This causes the excess water vapor to condense and turn into liquid water, making for a wet garage floor. Don’t fret, there are ways to solve this from happening. 

Why is your garage floor sweating a concern? 

Putting on my OSHA hat for a second, there are several reasons why your garage floor sweating is a concern. First, there are health risks. Mold can grow in damp, dark, corners over time. This can trigger allergies and other respiratory problems if left uncleaned. Another concern is that pooled water can cause the concrete to become slick and dangerous. If someone were to slip and fall in a garage, the list of injuries from meeting the floor at that velocity is a long one.  Outside of health concerns, excess water can also damage tools and other items that you might be storing in the garage. (There is nothing more maddening than a wet, soggy cardboard box!) Once you find yourself in that situation, the only thing to do is take a sad walk to the dumpster, to toss your ruined items. 

Where does the moisture come from making my garage floor sweat? 

Let’s dive right in. First, it helps to know what you are dealing with to prevent damage to yourself and your things. There are technically three ways that water can be forming on your garage floor. The most probable cause is that the warm moist air outside is coming in contact with the cool concrete, causing condensation to form and water to pool. The second possibility is that small salt deposits may have formed on your garage floor, from water that evaporated and left it behind. The nature of salt is to attract moisture, so this might be a good reason to finally get out there and scrub those garage floors. The third, and I would say, the least likely, reason is hydrostatic pressure. This is where moisture underneath the garage floor slab is pushing up through the concrete.  

So, Where Do I start? 

Check the Drainage in Your Garage 

If you are experiencing garage floor sweat and water building up on the concrete, begin by checking to see if you have a floor drain in the garage and that it is working properly. (Don’t worry if you don’t have a floor drain! There are other things you can do to help troubleshoot!) If you do have a drain installed, make sure it is cleaned out and clear of debris. Check that water drains properly through the drainage system. Trapped water in the drain line won’t help your current situation and can be contributing to the problem.  

Decrease the Moisture in the Air of Your Garage 

The main reason why garage floors sweat is due to moist air. So, one of the most effective ways to combat the issue is to install a dehumidifier in the garage. Having this running in the garage will pull much of the moisture out of the air allowing two things to take place. First, the air will be less likely to turn into water puddles, in the way we described above. Second, with less moisture in the surrounding area, water will more easily evaporate and will be less likely to liquefy and pool on your garage floor. 

Identify Anything Else that may Attract Moisture 

Another part of decreasing the moisture build-up is to be aware of what else is being stored in the garage. Do you have an old fridge or freezer? Are you storing salt for the water softener or gardening products that might be pulling moisture in? These items you may want to clean out, get rid of, or store differently if you are dealing with a garage floor that sweats.  

Other Preventative Measures 

Once these initial steps are complete, here are some other things you can do to help keep your garage floor from sweating: 

Circulate the Air in Your Garage 

Install a fan to circulate the air in the garage. This can help keep moisture from forming and will help water evaporate faster. You will need a fan that can push some air since the standard garage is 20’ by 20’. If you are looking at different fan types that would work in the space, I would suggest looking at a fan that you can get multiple uses out of. It is always nice to have a fan blowing on you if you are working out in the shop on a hot day, so keep that in mind when you are making your choice. I would suggest looking at one of these to do the job. 

Control Your Garage’s Temperature 

While keeping your garage climate controlled isn’t always feasible or economical, there are some instances in which this may work for you. If possible, increasing the temperature in your garage can be a valid solution to your moisture problem. By increasing the garage’s overall temperature, you will, in turn, be increasing the temperature of the concrete floor. Warmer concrete means that the air will be less likely be to hit its dew point, where the water vapor condenses into a liquid. A space heater could be a viable option for you, especially if you like to work in your garage in the winter and could find other uses for it. (I like to get as many uses as I can out of the tools and products that I purchase). Here is an example

Epoxy Your Garage Floor 

Aside from giving it an awesome finish, epoxying your garage floor can also provide several benefits when dealing with moisture buildup in your garage. First, it will force you to have the garage floor cleaned, removing any salt deposits that may have formed. Second, since the porous garage floor is sealed, the potential moisture that collects on the garage floor will not be able to soak into the concrete. Third, this will cause the water to sit above the epoxy, exposing it and increasing the surface area causing quicker evaporation, if paired with other methods discussed in this post. Lastly, future cleaning of your garage floor will be much easier since everything is sealed and the dirt, salt, and grime are all on the surface. 

For more information regarding epoxying your garage floor, check out these other articles. How To Prep, Seal, and Epoxy Your Garage and Best Epoxy for Garage Floors.

Seal Up Drafts in Your Garage 

You may also want to check out your door and window seals, and ask: “Are they in good condition?” Can you feel the air move or see sunlight when you look at the seals? Make sure your garage is properly sealed to keep out excess moisture. If air gaps around the doors and windows are trying to help vent the garage, tell them to knock it off and fill up those air gaps. You might want to look at this or this when creating those additional barriers in your garage to seal up around the bottom of your garage door, for the side entry door, and for the windows

Check Your Garage Vents 

Lastly, don’t overlook the ventilation in your garage. Check to make sure the vents in your garage and roof are working properly. Periodically these need to be inspected to make sure debris buildup has not formed and that adequate airflow is passing through the vents. If the vents are not working well, this can also cause moisture to get trapped in the garage. The vents are there to keep a balance between the air in your garage and the air outside. Ensure these are in good working order, and this should also help solve your problem! 


If your garage floor is sweating, do not let the problem persist. Take action and start implementing some changes that will help take care of the moisture that is collecting making your garage floor sweat. If you are starting to see some momentum with your garage, and now that your floors are dry, check out these next articles to renovate your space.

Thanks for reading, and as always, be sure to keep it tuned to The Garage Junkie for all of your garage’s FYI and DIY needs!

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