Removing the Guesswork: TDR’s New Calculator Aligns Scopes with the AS-IICRC S500 Standard

A Tool for Transparency and Faster Approvals

Our new calculator automates this complex IICRC formula. For our insurance and loss-adjusting partners, it provides an immediate, objective, and verifiable way to validate a restoration scope.

By aligning on the correct scope from Day 1, we get mitigation underway faster, prevent claim escalation, and ensure a better outcome for the policyholder. Ultimately, this helps us achieve our shared goal: minimising the total claim cost.

Disclaimer

Initial drying equipment requirements are determined in accordance with Institute of Inspection Cleaning and Restoration Certification (IICRC) guidelines and industry best practice. These calculations provide a baseline for the quantity and type of equipment to be installed on Day 1; however, they are indicative only and subject to site-specific conditions.

An IICRC-trained technician should assess the property at the time of installation to determine and document the appropriate equipment placement and quantities. This assessment will consider, but is not limited to:

The extent and category of water intrusion
Affected materials and their drying requirements
The layout and size of the affected areas
The presence, volume, and configuration of contents that may restrict airflow
Accessibility, safety constraints, and environmental conditions

It is important to note that high contents loading, restricted airflow, or complex building configurations may limit the effectiveness of standard calculations and require adjustments to equipment quantities and positioning. Any such variations should be documented to support and justify the equipment levels required.

Moisture levels should be monitored daily using industry-approved methods and equipment. Based on these readings, drying strategies and equipment levels should be progressively adjusted to ensure efficient and effective drying in line with IICRC standards. This may include increasing, decreasing, or relocating equipment as conditions change throughout the drying process, ultimately helping to maximise efficiency and reduce overall costs and timeframes.

Air Mover Calculator

Step 1 of 5

How many rooms are affected?

Count every room that has water damage. Each room automatically gets one air mover as a starting point.

💡 Count each separate room - including bathrooms, hallways, and walk-in-robes - as its own room if it has water damage.

Step 2 of 5 Wet Floor Areas

What are the wet floor areas?

Measure the wet floor area in each room (in square metres). This includes floors and lower walls up to about 60cm high - but only enter the floor area, not the walls.

📏 Not sure of the area? Multiply the length by the width of the wet section. For example, a 3m x 4m wet area = 12m².

Step 3 of 5 Walls & Ceilings

Any wet walls or ceilings above 60cm?

If water has reached walls above 60cm from the floor, or the ceiling, enter those areas here. If not, leave as 0 and skip ahead.

💡 This only applies to wall areas above 60cm from the floor. The lower 60cm is already covered by your floor measurement.

Step 4 of 5 Insets & Offsets

Are there any wall insets or offsets?

Count any nooks, alcoves, or bump-outs in the walls that are deeper than 45cm. Each one needs an extra air mover to dry properly. If there are none, leave as 0.

💡 An inset is where a wall steps inward (like a closet nook). An offset is where it steps outward (like a chimney bump-out). Only count those deeper/wider than 45cm.

IICRC S500 Air Mover Calculation

This calculator follows the IICRC (Institute of Inspection, Cleaning and Restoration Certification) standard worksheet for determining air mover requirements.

Step 1: Base Count

Install 1 air mover per affected room. This is added to both the high and low range.

Step 2: Floor Areas

Add 1 air mover for every 4.5m² to 6.5m² of wet floor. This includes lower walls up to ~60cm.

Low range = floor m² ÷ 6.5 (rounded up)
High range = floor m² ÷ 4.5 (rounded up)

Step 3: Walls & Ceilings Above 60cm

Add 1 air mover for every 9.3m² to 14m² of wet wall/ceiling area above 60cm.

Low range = wall/ceiling m² ÷ 14 (rounded up)
High range = wall/ceiling m² ÷ 9.3 (rounded up)

Step 4: Insets & Offsets

Add 1 air mover for each wall inset or offset greater than 45cm. Added to both ranges.

Note: When any calculation results in a fraction, always round up to the next whole number. In small rooms under 2.3m², one air mover may be adequate.

Lower Walls & Limited Flooring

Use this only when water has primarily affected lower walls and limited flooring (less than 60cm of water migration into the room). This replaces the main calculation - don't use both for the same room.

Affected linear metres of wall Measure along the base of all affected walls.

Dehumidifier Calculator

Step 1 of 5 Water Damage Class

What class of water damage?

Select the IICRC water damage classification. This determines how aggressively the space needs to be dried.

Step 2 of 5 Equipment Type

What type of dehumidifier?

Select the dehumidifier type being used. LGR (Low-Grain Refrigerant) is the most common in the restoration industry, used in about 90% of jobs.

Step 3 of 5 Drying Zones

How many drying zones?

A drying zone is any group of connected rooms where air flows freely. Adjoining rooms with open doors count as one zone. Rooms on different levels or separated by closed doors are separate zones.

💡 Open-plan kitchen/living/dining with open doorways = 1 zone. A bedroom upstairs with its door closed = separate zone.

Step 4 of 5 Zone Volumes

What are the zone sizes?

Enter the total floor area for each drying zone and the average ceiling height. The calculator uses air volume (floor area × ceiling height) to size dehumidifiers.

Average ceiling height

Dehumidifier AHAM rating The AHAM-rated extraction capacity per unit (e.g. 50 for a 50 L/day unit). Check the manufacturer spec sheet.

Dehumidifier CMH rating The cubic metres per hour airflow rating of the desiccant unit.

💡 For a zone covering multiple rooms, add all floor areas together. For example: kitchen 12m² + dining 15m² + hallway 8m² = 35m² total zone area.

IICRC S500 Dehumidifier Calculation

This calculator follows the IICRC S500 Initial Dehumidification Recommendation factors and formulas.

Step 1: Air Volume

Calculate the total air volume for each drying zone:

Volume (m³) = Floor Area (m²) × Ceiling Height (m)

Step 2: IICRC Factor Chart

Select the chart factor based on damage class and dehumidifier type:

Step 3: Refrigerant Formula (Conventional & LGR)

Divide air volume by the chart factor to find litres per day (LPD) required, then divide by the unit’s AHAM rating:

Volume ÷ Chart Factor = Total LPD required
Total LPD ÷ AHAM Rating = Number of Dehumidifiers (round up)

Step 3 (alternate): Desiccant Formula

Multiply air volume by the ACH factor, then divide by the unit’s CMH rating:

Volume × ACH ÷ CMH Rating = Number of Dehumidifiers (round up)

Note: Conventional refrigerant is not applicable for Class 4 (Specialty Drying) — use LGR or Desiccant instead. Always use the AHAM-rated capacity of the specific unit being deployed. Actual requirements may vary based on ambient conditions and equipment. Restoration companies should record the IICRC class in their drying reports.