Why drying takes more than a fan
After the standing water is gone, a lot of water remains inside walls, under floors, in framing and in the air. Household fans move air but don't remove moisture from it, and opening windows can make things worse when outdoor air is humid. Professional drying uses equipment designed to pull water out of materials and out of the air, and measures progress until materials are back to normal moisture levels.
The equipment
- Air movers blow high-velocity air across wet surfaces to speed evaporation.
- Dehumidifiers remove the evaporated moisture from the air so it doesn't settle back into materials. Refrigerant and desiccant dehumidifiers each suit different conditions.
- Wall cavity drying systems push dry air into wall cavities through small holes, which can save drywall that would otherwise be cut out.
- Hardwood floor drying mats draw moisture out of wood flooring.
- Heat is sometimes used to speed drying in specific situations.
The amount of equipment depends on how much area is wet, the materials involved and the conditions in the house. A small leak might need a couple of machines; a flooded floor might need dozens.
Monitoring and documentation
A professional drying job is measured, not guessed. Technicians use moisture meters and thermo-hygrometers to record moisture levels in walls, floors and framing, and temperature and humidity in the air, usually daily. They compare wet areas with dry reference areas of the same material in the house. Equipment is moved, added or removed based on the readings. Drying is done when materials reach normal moisture levels, not when they feel dry to the touch.
Ask for copies of the moisture logs. They show your insurance company the work was necessary and confirm the house is actually dry before walls and floors are closed up.
How long it takes
Most structural drying takes several days, depending on how much water there was, how long it sat, what materials got wet and the conditions inside and out. Dense materials such as hardwood, plaster and concrete take longer. Water trapped under vinyl flooring or behind tile may require removing those materials to dry what's underneath.
Living with the equipment
Drying equipment is loud and uses a lot of electricity. It needs to run continuously, so don't switch it off at night. Keep doors and windows closed unless the technician says otherwise, and keep children and pets away from cords and equipment. If you have to leave the house, tell the contractor so they can plan access for daily checks.
Mold prevention
Mold can start growing on wet materials within a couple of days. Fast, thorough drying is the best prevention. If the water sat for a while before drying started, or if you see or smell mold, tell the contractor. They may recommend antimicrobial treatment or removal of affected materials.
Questions to ask
- How will you measure moisture, and can I see the readings?
- How long do you expect drying to take?
- Will you use wall cavity drying to save drywall where possible?
- What happens if materials aren't drying as expected?
- Who decides when it's dry enough to rebuild?
When materials can't be saved
Some materials dry well; others don't. Particleboard cabinet bases, laminate flooring and some engineered wood products swell permanently once soaked. A good contractor tells you early which items are likely to be lost, so you can plan and inform your insurer.