Measuring Water Damage: Square Footage and Flood Cuts

After a water loss, the claim and the restoration both run on measurements: how much floor got wet, how much drywall comes out, how much baseboard and insulation goes with it. Here's how to measure each, with a worked example for two rooms.

1. 1

   Map the moisture

   Use a moisture meter to find where the wet stops, on the floor and up the walls. The visible stain understates it.
2. 2

   Measure the affected floor

   Length × width of the wet area in each room, plus the flooring material (carpet and pad, vinyl, wood, tile).
3. 3

   Measure the wet wall runs

   Linear feet of wet wall in each room, per side, less doorways. Note interior walls wet on both faces.
4. 4

   Apply the cut height

   Drywall area = cut height × linear feet, for each side. Divide by 32 sq ft for 4×8 sheets.
5. 5

   Document every room

   Dimensions, photos, dated moisture readings and a floor plan with the affected areas marked.

How do you measure the affected floor area?

Measure each room's wet area as length × width, splitting irregular areas into rectangles. If the whole room is wet, that's the room's floor area. Carpet and pad are usually discussed in square yards: divide square feet by 9. Note the material in each room, because it drives what's dried in place and what's removed.

How high is a flood cut?

A flood cut removes drywall in a straight line above the wet area so the wall cavity can dry and be inspected. There are two common approaches:

The heights above come from an AIHA Synergist article on water intrusion (February 2024), which explains the 24 and 48 inch cuts by the 48 × 96 inch drywall sheet. The 2 ft and 4 ft cuts are measured from the floor, not from the waterline.

How do you calculate flood-cut drywall?

Drywall area = cut height × linear feet of affected wall, for each side. Take the room's perimeter and subtract doorways and any walls that stayed dry. An interior wall that's wet on both faces counts once in each room, which is right: both faces come out. Exterior walls only have the inside face, but wet insulation behind the cut often comes out too, over the same area.

Baseboard comes off along the same runs, so the linear feet of wet wall is also the baseboard to remove and replace.

Worked example: two rooms

Water covered the floor of a 16' × 14' living room and a 12' × 12' bedroom and wicked up every wall in both. Each room has two 3 ft doorways.

So the loss is 368 sq ft of flooring (40.9 sq yd of carpet and pad if that's what was down), 96 linear ft of baseboard, and either 192 or 384 sq ft of drywall depending on the cut. Total the rooms before rounding sheets: rounding each room separately gives 7 sheets at the 2 ft cut instead of 6. Add a spare for breakage.

The flood cut calculator does this from each room's length and width, the cut height and the total width of the doorways. For full-height drywall replacement, use the drywall calculator.

Where does IICRC S500 fit in?

The industry standard for professional water damage restoration is ANSI/IICRC S500, currently the 2021 (5th) edition. Restorers use it to assess, classify and dry a loss. Its water classes are commonly described by how much of a room's combined floor, wall and ceiling area is wet porous material, from Class 1 (little) to Class 3 (most), with Class 4 for deeply bound water. That's another reason to measure all three surfaces: the living room above has 224 sq ft of floor, 480 sq ft of wall and 224 sq ft of ceiling, 928 sq ft in all. Check the current S500 for the exact class definitions.

How to document rooms for a claim

• Room sizes: name, length, width and ceiling height of each affected room, with floor area and perimeter.
• Affected areas: wet floor area and material; which walls, how many linear feet and the cut height; baseboard length.
• Moisture readings: dated, with locations, so the cut heights are supported.
• Photos: a wide shot of each room, then close-ups of the damage and the meter readings.
• A floor plan with dimensions and the affected areas marked.

Xactimate, from Verisk's Xactware, is the standard software for estimating property claims; Verisk says it's used by 80% of the top property insurance carriers. Whoever writes the estimate needs the same room dimensions either way. Your policy and your adjuster decide what's covered; this is about getting the measurements right.

Room sizes from a floor plan in FloorFigures

If the home's floor plan is available (builder plans, a listing floor plan, even a phone photo of a printed plan), open it in FloorFigures. It's free, runs in your browser and doesn't upload the plan. Find the rooms with one click each and you get every room's dimensions, floor area, perimeter and wall and ceiling area. With no plan, sketch the rooms on a blank sheet and type the wall lengths as you measure. Export a PDF report with the marked-up plan and a room schedule, or a CSV.

FloorFigures doesn't integrate with Xactimate; it gives you the room sizes to enter. More for claims work on FloorFigures for adjusters and restoration.