A flooded basement is dried in order: the water is removed and the source stopped, the materials are read, anything that cannot be dried is removed, and the structure is dried to measured goals. Mold is kept from starting by moving quickly through those steps, and any growth found later is handled after the structure is dry.
Key takeaways
- Water out first, then drying: standing water is removed and the source stopped before any drying equipment runs.
- Drying is measured. The work is finished when the readings reach the goal on every check, not when the surface looks dry.
- Drywall and insulation that have taken up water are often removed, because they cannot be dried reliably.
- Mold grows on wet materials over days. Speed and steady readings lower the risk.
- Growth found after drying is handled under its own plan and is not painted over.
What is the first step in a flooded basement?
The first step is to stop the source if it is still running and to remove the standing water. Power to the wet area is confirmed off before anyone enters the water.
Check whether water is still coming in, from the ground, a sump, a drain or a pipe. A sump that has failed or a drain that is backing up has to be dealt with first, or the pumping will be working against an open source.
Confirm the power to the basement is off at the panel if it can be done safely from a dry place. Do not enter a basement with water near a live outlet or a panel.
How is the water removed from the basement?
Submersible pumps and extraction equipment remove the water, and the crew paces the pumping against the ground around the walls. Pumping too fast can damage the walls, and pumping too slow leaves the materials wet longer.
The pump is set at the lowest point and run from a protected outlet outside the water. Silt and debris are cleared as the water falls, since they hold moisture against the floor.
Once the standing water is out, the floor and walls are read for the moisture that remains in the materials.
The pump should be set to draw the water out at a rate the crew agrees, and the discharge should be placed where it will not flow back toward the foundation. A discharge hose that runs back to the same wall can undo the work of the pump.
Why do the walls and slab need readings?
Concrete, block and the soil behind them hold moisture for a long time after the water is gone, and a wall can look dry while it is still wet inside. Readings in the material show the real condition.
A pin meter or a non-invasive reading in the block, the slab and the framing shows the moisture inside the material. A humidity reading in the room air is useful too, but it does not show the material.
The readings are taken at set points and recorded, so the drying can be checked on each visit.
When does drywall and insulation come out?
Drywall that is soft at the base, insulation that has taken up water and material that has been wet for a long time are usually removed, because they cannot be dried reliably. Solid masonry and framing are often dried in place.
Drywall is marked at the height the water reached, and a small opening is made where the readings are high, so the cavity can be checked. Board that is soft or crumbles is removed to the framing.
Insulation that has soaked is removed and replaced after the cavity tests dry. The crew shows you what is coming out before it goes.
How does drying actually proceed?
Air movers move air across the wet surfaces and dehumidifiers pull moisture from the room air. The equipment is set to the layout of the basement and checked on each visit. The drying runs until the readings reach the goal.
The equipment is placed so the air reaches the walls and the floor, and the room is kept as open as the plan allows. Sealing the room traps humidity and slows the work.
A basement can take much longer to dry than a room above ground, because the ground keeps supplying moisture. The crew explains the expected range and does not promise a finish date.
Keep the drying equipment away from the walls it is drying, so that its warm exhaust does not blow across the same surface. A dehumidifier and an air mover placed to create a moving path are more effective than one aimed at a single wall.
How is mold kept from starting?
Mold needs moisture, a food source such as paper or wood, and time. Fast removal of water, steady drying and removal of soaked porous materials cut off the first two and shorten the third.
Stored boxes, paper and fabric in a flooded basement are the first things to grow mold. Photograph and remove them where they cannot be dried, rather than leaving them in a damp room.
Keep the basement ventilated only as the crew advises. Open air can add humidity in some weather, and the crew will say when opening a window helps.
What if mold appears after the drying?
Growth found after the structure is dry is recorded and handled under its own plan. It is removed or cleaned, not painted over, and the moisture that allowed it is traced and stopped first.
Painting over growth on a damp surface hides the problem for a short time and lets it return. The moisture has to be controlled before the surface is cleaned and finished.
This guide does not give medical advice about mold. If anyone in the house has a health concern, speak to a doctor.
What does the air in a basement need during drying?
A basement that is drying needs air that is moving across the wet surfaces and a dehumidifier that pulls moisture from the room air. Air that is still and humid slows the drying, and air that is moved without being dehumidified can simply move the moisture around.
The crew places the equipment to give the air a path across the walls and floor, and it sets the dehumidifier to the room's conditions. The layout is checked on each visit, since a change in the room can change the best setting.
Keep the doors between the basement and the rest of the house closed where the crew asks, and keep the furnace and any other fuel-burning appliance serviced by its own trade. This guide does not advise on those systems.
How do I tell if the drying is working?
The readings are the test. If the readings in a material fall visit by visit toward the goal, the drying is working. If they stall or rise, something is wrong: a source is still active, the air is not moving, or the material is wetter than the crew assumed.
Ask the crew to show you the readings on each visit, and ask what it expects the next reading to be. A visible change, such as a stain that stops spreading or a floor that stops feeling cool, is a sign of progress, but the readings decide the finish.
A reading that stops falling is a reason to look again, not a reason to close the wall. The crew will look at the source and the layout before it decides the next step.
What should I do with stored boxes and fabric?
Stored boxes, paper, fabric and cardboard that were in a flooded basement hold water and grow mold quickly. Photograph them where they sit and remove them to a dry area or discard them after they have been recorded.
Do not stack wet items to dry them, since stacking traps moisture. Spread items out where the air can reach them, and keep them away from the drying equipment and its hoses.
Keep a list of anything of value that was in the basement, with its approximate age and condition. The list is the basis of any claim for belongings, and it is easier to make while the items are in view.
How long should I expect the basement to stay out of use?
There is no fixed number of days, because the drying and any repair depend on the materials and the readings. A basement can be used again for storage once the readings reach the goal, and for living space only after the finishes have been repaired and read as dry.
The crew explains which parts of the basement can be used at each stage. A room with its finishes removed may still be unsafe to use while the equipment is running, and a room with a finished floor should stay clear until the trade has finished.
Plan around the drying, not against it. Moving furniture back early can trap moisture behind it and slow the work, and it can hide growth that the crew would otherwise see.
Frequently asked questions
How long does a flooded basement take to dry?
It depends on the materials and the air. The work is finished when the readings reach the goal on every check, and the crew explains the expected range on the first visit.
Can the crew dry the walls without removing the drywall?
Sometimes. Drywall that has not softened can dry in place. Where the readings stay high or the board is soft, a section is removed.
Should I run a dehumidifier myself?
A dehumidifier helps a dry room hold its humidity, but it does not dry a flooded building. The crew sets the equipment and checks the readings.
Will mold grow in a basement that was flooded?
It can, if moisture stays high for days. Moving quickly through removal and drying lowers the risk, and any growth found is handled after the structure is dry.
Who repairs the walls and floor after drying?
The trades that do that work, after the readings show the structure is dry. The crew will tell them what it found.
Can I speed up the drying with a space heater?
A space heater warms the air but does not remove moisture from the materials, and a heater left running near wet materials or water is a fire and shock risk. Leave the drying to the equipment the crew sets.
Will the basement smell the same after drying?
A smell that remains after the readings reach the goal can come from materials that were not removed, from a source that is still active or from the drain. Tell the crew, and it will read the area again rather than leave the smell to pass on its own.
This guide is general information for Champaign County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.