Moisture-Resistant Drywall Requirements in Wet Areas (IRC R702.4.2)

What is moisture-resistant drywall?

Standard drywall (white paper facing) absorbs water and is a prime substrate for mold growth. Moisture-resistant drywall (often called green board because of its green paper facing) has a water-resistant core and facing. Cement board and fiber cement board are even more moisture-resistant and are required behind tile in shower and tub surrounds.

Each type costs more than standard drywall but is essential in wet areas.

Where is it required?

IRC R702. 4. 2 requires moisture-resistant materials in areas subject to moisture.

This includes bathrooms (all walls in the room, not just shower areas), behind kitchen sinks, laundry rooms, and any area with plumbing fixtures. Shower and tub surrounds specifically require cement board or equivalent, not just moisture-resistant drywall. These are minimum code requirements that must be met when drywall is replaced.

Why does this come up in insurance claims?

Many older homes have standard drywall in bathrooms and kitchens because the code was different when they were built. When water damage requires replacing this drywall, current code applies to the replacement. You cannot install new standard drywall in an area where code requires moisture-resistant material.

The building inspector will not approve the work, and the repair cannot be completed.

What does it cost?

Standard drywall costs $0. 30-$0. 50 per square foot for the material.

Moisture-resistant drywall costs $0. 50-$0. 80 per square foot.

Cement board costs $0. 80-$1. 50 per square foot.

The difference per sheet is $3-$8, but when you add it up for an entire bathroom or kitchen, plus the additional fasteners and joint treatment required, the upgrade adds $200-$600 to the repair cost.

What to do

If your repair involves replacing drywall in a kitchen, bathroom, or laundry room, check that the estimate specifies moisture-resistant drywall or cement board where required by code. If it simply says 'drywall' without specifying the type, ask your adjuster to clarify. This is a code compliance issue covered under your Ordinance or LawBuilding Code Upgrades in Insurance ClaimsWhen your home is opened up for repairs, existing construction that does not meet current building codes may need to be upgraded. This is covered u...
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