How Many Air Movers and Dehumidifiers Does a Water Damage Job Need?

Every adjuster, every carrier and every IICRC S500 class tells you the same thing: drying is a numbers game. Put too little equipment on a loss and the job runs four extra days; put too much and you are paying for units that sit idle. This is the quick math our customers use when they are standing in a wet living room with a clipboard.

Step 1: Measure the wet area, not the room

Walk the loss with a moisture meter and mark the actual wet footprint: square feet of wet floor and linear feet of wet wall. A 20 x 15 room with water only along one 15-foot wall is a 15-linear-foot problem, not a 300-square-foot one. Everything below scales from those two numbers plus ceiling height.

Step 2: Air movers

The S500 standard gives a range rather than a single number, and most crews land on this rule of thumb:

• One air mover per 50–70 sq ft of wet floor on open areas.
• One air mover per 10–16 linear ft of wet wall, aimed at a 5–45 degree angle along the wall so the airflow sweeps the surface instead of hitting it head-on.
• Add one unit for each inside corner, closet or cabinet toe-kick where air stalls.

For a 1,000 sq ft Class 2 loss with roughly 120 linear feet of wet wall that works out to 8–12 air movers, which is exactly why the 1,200 sq ft Pro package ships with eight AM33 units. Under cabinets and vanities, swap in AM30LOC low-profile units; they push air where a snail-style mover physically cannot reach.

Step 3: Dehumidification

Air movers only move water into the air. If you do not pull it back out, humidity climbs, drying stalls and you risk secondary damage in rooms that were never wet. S500 sizes dehumidifiers by cubic feet and class of loss, and always on the AHAM rating (80°F / 60% RH), not the saturation number on the box:

1. Multiply wet square footage by ceiling height to get cubic feet.
2. Divide by the S500 factor for your class. For the Class 1–2 losses that make up most residential work on LGR equipment, plan on roughly one AHAM pint per day for every 100 cubic feet. Heavy Class 2 and Class 3 losses (soaked drywall, hardwood, plaster) use a much lower factor, so budget up to double.
3. Round up to whole units.

Example: 1,000 sq ft x 8 ft ceilings = 8,000 cu ft. At the baseline factor that is 80 AHAM pints per day: one DH80 (80 AHAM / 150 saturation) covers it, and on a heavier loss a second DH80 or one DH155W (155 AHAM / 268 saturation) gives you the margin.

Step 4: Air scrubbers are not optional on Category 2 and 3 water

Grey and black water losses, and any job where you are cutting drywall or pulling carpet pad, need HEPA filtration and usually negative pressure. Budget one 500 CFM scrubber per 1,000–1,500 sq ft of work area, or step up to a 1,000 CFM unit for open commercial floors. Our restoration packages include scrubbers in the same ratio.

Putting it together

Every MOUNTO package is built on exactly this math at the baseline factor, so the table doubles as a package guide:

Standard, Pro and Elite tiers change only the air-mover density (roughly 4, 6 and 10+ units per 1,000 sq ft); the dehumidifier and scrubber counts stay matched to the square footage. If the loss is a heavy Class 2 or a Class 3, buy the next package size up or add a dehumidifier rather than more air movers.

Three mistakes that cost drying days

• Running air movers without enough dehumidification. Relative humidity above 60% in the drying chamber means you are recirculating moisture, not removing it.
• Skipping daily readings. Log temperature, RH and material moisture every 24 hours. If material readings are not dropping, add dehumidification before you add air movers.
• Overloading circuits. Plan on one 15 A circuit per two to three air movers plus one dedicated circuit per dehumidifier, and daisy-chain through the GFCI outlets built into MOUNTO movers instead of extension-cord spaghetti.

Not sure which package fits the losses you see most often? Email info@mounto.com with your typical square footage and we will size it with you. Everything ships from Corona, CA within 1–2 business days.