Drying Equipment Calculator (IICRC S500 method)
Estimate the dehumidifier capacity and air movers a water-damaged area needs.
Estimates use typical industry ranges and published methods. They are not a quote. An on-site moisture inspection sets the actual scope.
How structural drying works
Drying is a balance of three things: airflow across wet surfaces to evaporate moisture, dehumidification to pull that moisture out of the air, and temperature to speed evaporation. Air movers without dehumidifiers just push humid air around; dehumidifiers without airflow dry slowly. Professional drying combines both, sized to the job.
The equipment
- LGR (low grain refrigerant) dehumidifiers keep pulling water from the air at lower humidity levels where household units stall.
- Air movers blow high-velocity air along walls and floors. Placement follows IICRC guidance: typically one per wet room, plus one per 50–70 sq ft of wet floor.
- Desiccant dehumidifiers for dense materials and cooler conditions.
- Injection and wall-cavity drying systems that push dry air into walls through small holes instead of removing drywall.
- Hardwood floor mats that pull moisture up through wood flooring.
Classes of water loss
The IICRC S500 standard groups water losses into four classes by how much water was absorbed and how fast it will evaporate. Class determines how much dehumidification capacity is needed. The calculator above follows that method: cubic feet of the space divided by a class factor gives the pints of water per day the equipment should remove. Learn more in the categories and classes guide.
Monitoring: how you know it's dry
Every day of drying should include moisture readings at mapped points, plus temperature and humidity readings inside the drying area and outside it. Drying is complete when wet materials read the same as an unaffected reference area of the same material, not when they feel dry. Those daily logs are also the documentation your insurer will look for.
Why not just rent a dehumidifier?
A big-box rental or household dehumidifier is rated around 30–50 pints a day under ideal lab conditions and pulls far less once humidity drops. A water-damaged living room and hallway can need 100–200+ pints a day of capacity, plus a half-dozen air movers and enough separate circuits to run them all.