Water in a garage is not a problem you can put off until later. Even a small flood slowly breaks down concrete, block and metal, and it brings mold, a musty smell and corrosion on the car. It is worse when water shows up in the garage again and again: that means moisture is getting into the structure, and pumping it out only helps for a while.
During long, heavy rains, garages and utility rooms are the first to be at risk. Below is what to do with a flooded garage: why it floods, how to find where the water comes from, what to do first, what to save, and how to keep it from happening after the next storm in El Cajon.
Safety first: power and gas
If the water has risen to the outlets or junction boxes, first shut off the power at the home's main electrical panel. If that cannot be done safely, it is better to call the power company or an electrician.
Ready.gov's flood safety page puts it plainly: do not touch electrical equipment if it is wet or if you are standing in water. Turn off the electricity only if it is safe to do so.
Do not walk into a flooded garage if you suspect the wiring is damaged. Do not stand in the water while the power is still on.
Moisture sharply lowers the resistance of wire insulation and raises the risk of a short circuit and electric shock. Even when the water is already gone, moisture can stay inside outlets, switches, junction boxes and appliances.
- Until the garage is fully dry, do not turn on the lights, appliances, pumps or power tools that are plugged into the garage wiring.
- If you need equipment for the cleanup, power should be fed only after the wiring has been checked by an electrician.
- For temporary use, outdoor-rated extension cords and equipment are better, and only if they are not sitting in water and are plugged into a dry, GFCI-protected outlet.
A gas water heater in the garage
Gas and electrical connections should be checked by the gas utility, a plumber or an electrician. If the water reached a gas water heater, leave it alone until the gas connection has been checked. If you smell gas, leave the garage and call the gas company from outside. Outlets and switches are checked and dried by an electrician, and only then is the power turned back on.
Where the water is coming from
Before any work, you need to understand where the water gets in. That decides the choice of waterproofing, drainage, pump and other protection. The same symptoms can have different causes:
- A driveway that slopes toward the garage. Rain from the whole driveway runs straight to the door.
- Missing or damaged waterproofing on the outside of the foundation and walls.
- Drainage around the garage that does not work or does not exist at all.
- Cracks in the foundation, walls and floor, or where structures meet.
- Leaks from water supply lines, the sewer or the irrigation system on the lot.
- The wrong slope on the paving around the garage, so rain runs toward the garage walls.
- Poor sealing of the garage door, vents and other openings.
If water seeps up through cracks in the slab after days of rain, the soil under the garage is soaked. Much more often, though, the water runs in under the door. If puddles appear only after rain and sit near the door, check the paving slope, the storm drains and how tight the door is at the threshold.
- Check the walls all the way around. Water can seep through cracks, cold joints and the joints between concrete blocks.
- Look at the floor. Water coming up through joints in the slab means the soil under it is soaked.
- Check where utility lines come in. Unsealed holes around pipes are a common path for moisture.
- Look outside. Note the condition of the paving, downspouts, channel drains and the lay of the lot.
If water keeps coming in through a drain, the storm sewer, cracks or the doorway, deal with the cause first, otherwise the pumping will be useless.
What to do first
When the garage floods, act in order. The main task is to keep people, the car and the equipment safe, and then stop more water from coming in.
- Shut off the power to the garage if the water is near outlets, the panel, extension cords or appliances.
- Take out of the water belongings, tools, chemicals and anything that can be ruined or become a hazard.
- Find the rough source of the water: walls, floor, door, utility lines or ceiling.
- Pump the water out. A small amount can be removed by hand, but with a steady inflow a pump with an automatic float works better.
- Send the water away from the garage so it does not come back to the foundation and does not flood the neighbors.
- After drying, air out the garage and remove dirt, silt and debris.
- Look into the cause of the flooding, and only then choose how to repair.
Pumping out a flooded garage: pump and wet-vac
If there is not much water, it can be removed by hand or with a wet-vac, a shop vacuum that picks up liquid. With serious flooding, you need a submersible utility pump.
Most household models are made for clean or slightly dirty water with small debris. But if there is a lot of sand, silt or trash in the water, you need a pump built for heavily soiled water. The pump is chosen by the volume of water, what is in it and the distance to the discharge point.
Point the discharge hose where the water cannot get back in.
When the floodwater outside is still close to ground level, pumping is a wasted effort, because the water will come back.
Pumping is not waterproofing. It removes the result, not the cause. Why speed matters for what is left underfoot is covered in this guide to fast water extraction.
Drying the garage
Once the water is out, the garage needs to be dried as soon as possible. Open all vents, windows and doors. If you can, use a dehumidifier: it removes leftover moisture faster and lowers the risk of mold. Fans can sometimes help with drying, but they should be plugged only into a dry, GFCI-protected outlet.
Do not dry wet walls with strong heat, though: it can crack the surface and ruin the insulation and the wall finish. Natural drying works best in sunny weather with a light wind that carries the moisture out through open windows and doors. More about how this is handled is on the water damage restoration service page.
Don't close off the vents: too little air exchange raises the humidity and helps mold grow.
What to save and what goes
Take everything out of the flooded area. Metal items, after cleaning and disinfecting, can go back in their place.
- Tools and power tools should not be switched on until they and the garage wiring are completely dry and checked.
- Appliances that stood in the water follow the same rule: no power until the garage is dry and the wiring has been checked.
- Furniture and bedding soaked with water and mud are probably not usable any more, and it is better to throw them out than to keep a source of dangerous bacteria.
- Particleboard shelves and cabinets that swelled should go as well; solid wood can often be dried and cleaned.
When there are many boxes and belongings to move out and sort, see how pack-out services for water damage work.
Garage wall drywall and insulation
After the water is pumped out, check for water left inside the walls. To do this, a moisture meter is pressed against the drywall at several points along the bottom of all the walls.
If the cavity is filled with fiberglass or another insulation, it will be hard to save and dry. That insulation is now worth nothing, and as it warms up mold and fungus will grow. After the garage is dried and disinfected, the insulation has to be put in again.
If mold has spread on the walls, the wall finish (drywall in most garages) around the infected spot is cut out and replaced; how far is decided after an inspection. All of this has to be finished before any interior finishing starts.
The garage floor
A concrete slab that was under water for a day or two usually needs only cleaning and time to dry. Cracks that let water up through the floor are sealed once the slab is dry. Don't put rubber mats, a floor coating or anything airtight on concrete that is still damp: the moisture stays trapped under it.
Door threshold and drainage fixes
Once the garage is completely dry, check the walls and floor for cracks and places where water gets in. Small defects can be sealed with waterproofing compounds or sealants. If the garage flooded after rain more than once, the problem is better solved as a whole: drainage around the building, repairing the paving, cleaning the storm drains and sending rainwater away from the foundation.
A drain at the garage door
On a driveway that slopes down to the garage, rain runs straight at the door. The usual fix is a trench drain: a channel with a grate set across the driveway just outside the door and piped to a spot where the water can drain away from the house. A rubber threshold seal on the floor under the door and a new bottom seal on the door itself keep out wind-driven rain. Downspouts that empty onto the driveway are extended or turned away from it.
Garage flooding solutions for the long run
- Keep the paving sloped away from the garage walls.
- Do not let water collect next to the foundation.
- Check how tight the roof and the garage door are, especially at the threshold.
- Clean drain inlets and downspouts of leaves and debris, and check them before the rainy season.
- Keep the garage ventilated at all times.
Mold after a flooded garage
If the garage is not dried quickly and properly, mold develops. After a flood the whole garage should be disinfected. There are many products for this; handle them carefully and work in gloves and a mask. When mold has already taken hold, see the mold remediation service page.
Who does this work in the area is described on the about us page, what homeowners say is on the customer reviews page, and other water damage articles are collected on the blog with more articles. The full list of services starts from the El Cajon restoration home page.