After a summer thunderstorm floods your garage, cut the power to the garage if you can do it safely, keep out of the water until you know there’s no electrical hazard, and photograph everything. Then get the water out, pull wet boxes and debris, clean up any spilled chemicals, and check the wall and door you share with the house, because that’s where storm water quietly gets into living space. Storm flooding garage cleanup is mostly about safety and speed: floodwater from outside isn’t clean, and drywall and stored items start soaking it up right away.
Why garages flood in summer storms
Middle Tennessee summer storms tend to build fast on hot afternoons and dump a lot of rain in a short time. Storm drains and yards can’t keep up, and water takes the easiest path downhill. A garage is often that path. Common reasons:
- A driveway that slopes down toward the garage door
- A worn or missing rubber seal along the bottom of the door
- Gutters overflowing or downspouts dumping right next to a side door
- A clogged trench drain or yard drain
- A slab that’s lower than the surrounding grade, common on some lots
- Heavy runoff from a neighbor’s yard or street after hours of rain
The National Weather Service in Nashville posts flash flood watches and warnings, and those are worth paying attention to on stormy summer afternoons. If a warning goes out and your garage has flooded before, it’s a good moment to pull boxes off the floor and move the car to higher ground.
What to do first, in order
- Stay out of standing water near outlets, cords, a freezer or the water heater until power is off.
- Shut off the garage circuits at the breaker panel, but only if you can reach the panel without walking through water.
- If you smell gas, leave and call your gas company from outside.
- Take photos and video of the water level, the stored items and the walls before you move anything.
- Move the car out if it’s safe and the water didn’t get inside it. If it did, leave it alone.
- Open the big door once the rain stops, so water can drain out and air can move.
- Push or vacuum out the water. A squeegee and a wet/dry vac handle shallow water. Deeper water needs a pump.
- Check the door into the house and the floor on the other side right away.
The garage, zone by zone
The floor
Concrete handles water fine, but floodwater leaves mud, silt and sometimes oil films behind. Once the standing water is out, scrub the floor with a stiff broom and a detergent solution, then rinse toward the door. If the water picked up oil or chemicals, soak it up with absorbent material first rather than spreading it.
The walls
Many attached garages have drywall, at least on the wall shared with the house. Drywall wicks water upward, and storm runoff isn’t clean water. The usual approach is to cut the drywall a foot or two above the highest waterline, pull any wet insulation, let the framing dry, and replace it once it tests dry. Our post on when drywall needs to come out goes into the details.
Appliances
Water heaters, chest freezers, second refrigerators and washers often live in the garage. If water reached the controls, burner area or compressor, don’t fire it back up until a qualified tech has looked at it. A submerged gas water heater is a real safety concern.
Stored stuff
This is usually the biggest pile. Cardboard boxes collapse and wick water into whatever’s inside. Sort it fast, because the longer things sit wet in a hot garage, the more likely mold and odor become.
What to toss and what to clean
Use this checklist when you’re sorting items that sat in storm water:
- Toss: wet cardboard, paper, books, mattresses, upholstered furniture, pet food, stuffed animals, particleboard shelving, insulation
- Toss carefully: leaking containers of fertilizer, pesticides, paint or pool chemicals (check local household hazardous waste rules rather than putting them in the trash)
- Clean and dry: metal tools, plastic bins, bikes, hard plastic toys, lawn equipment (have small engines checked if water got into them)
- Get professional help with: important papers, photos and anything with sentimental value, which can sometimes be dried or frozen until it can be restored
- Have checked: any appliance or power tool that was submerged
Wear rubber boots and gloves while sorting. The CDC’s flood safety advice covers the basics of protecting yourself from contaminated floodwater.
Don’t forget the house side of the wall
This is the part people miss. The door from the garage into a mudroom, laundry room or kitchen usually sits only a step above the garage floor, and sometimes level with it. Water can get under that door or soak through the bottom of the shared wall.
Check these spots inside the house:
- Carpet or rugs right inside the door
- Baseboards and the bottom of the drywall on the shared wall
- Laminate or vinyl plank flooring near the door, which can trap water underneath
- Cabinets in a laundry room or mudroom on that wall
If anything on the house side is wet, treat it as a water damage job, not just a garage cleanup.
Drying the garage out after the water’s gone
Getting the water off the floor is the easy part. Drying is where people cut corners, and a hot, humid garage in July is a good place for mildew to start on framing and drywall paper.
Once wet drywall and insulation are out, open up the wall cavities so air can reach the studs and the bottom plate. Run fans aimed at the framing. Here’s the trade-off with the big door: on a breezy, dry day, leaving it open helps. On a sticky, humid day, you’ll often get better results closing it and running a dehumidifier so you’re not pulling more moisture in from outside.
The bottom plate (the horizontal board the studs sit on) is the piece that stays wet longest, because it sits right on the slab. Check it with a moisture meter before anyone hangs new drywall. If it’s pressure-treated lumber, it’ll hold up to getting wet better than untreated wood, but it still needs to dry before you close the wall.
Give it a sniff test a week later. A musty smell in a garage that didn’t have one before is a sign something is still damp, often behind a cabinet, under a workbench or inside a wall you didn’t open.
Two ways this tends to play out
The driveway that funnels water. Say your driveway slopes down to the garage, and a slow-moving thunderstorm parks over the neighborhood for an hour. Water sheets down the drive, overwhelms the little rubber seal on the door and spreads across the garage. It’s a few inches deep at the low end. The boxes on the floor are ruined, the bottom of the drywall is wet all the way around, and the water heater sits on a stand, so it stayed dry. Cleanup means pumping, sorting, cutting out the lower drywall and drying the framing. The long-term fix is a trench drain at the bottom of the driveway.
The side door and the mudroom. Now say a gutter over the side garage door clogs during a storm and overflows right at the threshold. Only a little water reaches the garage floor, but it runs under the interior door into the mudroom, where it soaks under vinyl plank flooring and into the bottom of a built-in bench. The garage needs a mop. The mudroom needs real drying, and the flooring may need to come up so the subfloor can dry.
Keeping the next storm out
- Clean gutters before summer storm season and add downspout extensions.
- Replace the bottom seal on the garage door, and consider a threshold seal on the floor.
- Install or clean out a trench drain across the driveway.
- Store anything you care about on shelves or in plastic bins with lids, at least a few inches off the floor.
- Raise the water heater and freezer on stands if they sit directly on the slab.
- Keep chemicals on high shelves in sealed containers.
- Look at the grading around the garage and fix low spots that hold water.
When to call for storm damage help
A shallow puddle on bare concrete is a DIY job. Call in help if water got into the house, the drywall is wet, there’s mud and debris throughout, appliances were submerged, or the storm also damaged your roof or siding. Our storm damage team handles water extraction, drywall removal, drying and emergency tarping or board-up if the storm opened the house up. If storm water also got into living areas, our post on what to do after storm water enters a home is a good next read.
Areas we serve
We handle garage flooding and storm cleanup across Middle Tennessee. In Mount Juliet and Hendersonville, our crews are typically on site within about 60 minutes, day or night.
If a storm just filled your garage, call Water Damage Pros TN at (629) 250-3594. We’re open 24/7, our technicians are IICRC certified, and we’ll help you document the damage for your claim. You can also request a free estimate online.
