The garage took on water — from a storm, a backed-up drain, a water heater failure, or street flooding that got under the door. Before you start sweeping it toward the drain, here is what you need to know about what’s already damaged and what you can still save.
Drywall on garage walls: Many garages in Houston have fire-rated drywall on the walls and ceiling — code requirement for the wall shared with the living space. Drywall wicks water upward from the bottom at approximately one inch per hour. A garage that had two inches of water for three hours has wet drywall at roughly the six-inch mark, even after the floor is dry. That wet drywall will mold within 48–72 hours if it isn’t dried out or removed.
Stored cardboard boxes: Gone. Cardboard absorbs water, collapses, and becomes a mold substrate almost immediately. If boxes were sitting in the water, everything inside is suspect — assess the contents and assume the boxes themselves are trash.
Anything with particle board or MDF: Shelving units, cabinets, and furniture with particle board or MDF cores swell and delaminate when wet. They can’t be dried and restored — once they’ve soaked in water, the structure is compromised. The finish may still look intact on the surface.
Power tools and electronics stored at floor level: Motors, batteries, and circuit boards that have been submerged need to be assessed before use. Some will work fine after drying. Others have internal corrosion that creates failure or fire risk. Don’t run flooded power tools until they’ve been inspected.
The water heater (if present): If your water heater is in the garage and was partially submerged, the thermostat, pilot assembly, and gas valve may be damaged. Have a plumber or HVAC tech assess before relighting it.
Concrete floors are not damaged by water — they may stain, but structurally they’re fine. Metal tools and equipment that aren’t motorized can be dried and cleaned. Solid wood that gets dried quickly (within 24–48 hours) typically doesn’t sustain permanent damage. Vehicles — if they didn’t take on water inside the cab or engine bay — are usually fine from a brief garage flood.
Texas building code requires fire-rated construction on the wall between the garage and living space — typically 5/8-inch Type X drywall. That wall is also the pathway for water damage to travel from your garage into your home’s wall cavities.
If the garage had standing water against that wall, moisture is wicking into the base of the drywall on both sides — the garage side and the living space side. The wall cavity between them is likely wet. This is the part of a garage flood that creates mold problems inside the house that don’t show up until weeks later.
Moisture meter readings on the shared wall at 12, 24, and 48 inches from the floor are the only way to know how far up the moisture traveled and whether the cavity needs professional drying.
This determines the entire cleanup approach. A garage flooded from a burst pipe inside the home is clean water (IICRC Category 1) — the concrete can be swept and mopped, tools can be wiped down, and drywall can potentially be dried in place if caught early.
A garage flooded from street water, storm runoff, or bayou backup is Category 3 — it contains motor oil, pesticides, animal waste, E. coli, and whatever else was in the street. Everything that absorbed that water is contaminated. The concrete may be fine after pressure washing and treatment, but porous materials that were submerged need to go.
If the water came from inside — a burst pipe, water heater failure, washing machine in the garage — almost certainly yes under a standard Texas HO-3 policy. Document before cleanup and file.
If the water came from outside during a storm — street flooding, storm drains backing up, bayou overflow — that is flood damage and requires a separate flood insurance policy. Standard homeowners coverage explicitly excludes this.
The concrete floor is the least of your concerns. The drywall, the shared wall with the house, and any porous materials that absorbed water are where the permanent damage happens. Know what source the water came from — because clean water and outside floodwater are completely different cleanup situations.
If your garage flooded and you’re not sure whether the shared wall with the living space was affected, call 247 Restoration Specialists for a moisture assessment. We can measure what’s wet and tell you whether you have a drying job or a remediation job before you start guessing.
Not necessarily — it depends on water category and how long it sat. Category 1 water (clean supply line) that was extracted within a few hours may allow drywall to be dried in place with professional equipment. Category 3 water (outside flooding, sewage) requires removal of all porous materials including drywall. Time matters: drywall that was wet for more than 24–48 hours in Houston’s humidity almost always needs to be removed to prevent mold.
For clean water: sweep, extract standing water, then let it dry. For Category 3 water (outside flooding): pressure wash, apply an EPA-registered antimicrobial cleaner, and rinse. Allow to dry completely before storing anything on the floor. If floor drains are present, have them inspected — they may be the entry point and may have backflow issues.
Usually not, from the flood itself. If water got inside the vehicle cabin or engine compartment, that’s a separate issue. Standing water under a car doesn’t damage the vehicle as long as the flood level didn’t reach the exhaust, air intake, or interior. However, if floodwater was contaminated and splashed into wheel wells or brake components, a car wash and brake inspection are reasonable precautions.
