Wet drywall: dry it in place or cut it out?

Drywall is gypsum pressed between two layers of paper ^[1]. Gypsum absorbs water and softens; the paper absorbs water, loses strength and provides food for mold once it stays damp. Drywall also wicks water upward from a wet floor, so a puddle on the floor can wet the bottom several inches of a wall within hours.

That means the clock and the water source matter more than anything else. Clean water, caught early, often leaves drywall that is wet but structurally sound, and air directed at it and into the cavity behind it can bring it back to normal. Water that sat for days, or water that carried sewage, soil or chemicals, changes the decision.

A flood cut is a straight, level cut along a wall a set distance above the highest wet point, often around a foot or two above it, with the drywall below removed. It exposes the bottom plate, studs and any insulation so they can be cleaned and dried, and it leaves a clean line for the repair. Flood cuts are standard after sewage backups and floodwater, when the lower part of the wall has been contaminated, and after clean water if the bottom of the board is too damaged to keep.

When drywall can be kept, restorers often drill small holes near the floor, behind where the baseboard sits, and blow dry air into the cavity. The holes are hidden once the baseboard goes back.

A wet drywall ceiling is more dangerous than a wet wall, because water collects on top of it and adds weight. A ceiling that sags or bulges can fall without much warning. Keep people out from under it, and let the contractor drain and remove it in a controlled way, as part of water extraction. Ceilings that got only a little wet and stayed flat can often be dried, though the insulation above is usually removed if it is soaked.

What is behind the drywall often decides the matter. Fiberglass batts in an exterior or basement wall hold water like a sponge and press it against the drywall and the framing. If they are soaked, they usually have to come out, and the drywall in front of them often comes out with them. Interior walls without insulation are easier to dry in place. Ask the contractor what is in your walls before deciding.

Basement walls deserve their own note, because so many Kansas homes have finished lower levels. Basement drywall is usually fastened to studs that sit on a bottom plate directly on the concrete slab, often with insulation or foam board behind it against the foundation. When water spreads across the floor, the bottom plate, the lowest part of the drywall and the insulation all get wet at once, and the cool, enclosed space slows drying. That combination makes flood cuts more common in basements than upstairs, especially after a sump failure, storm runoff or a floor drain backup.

If your basement was finished with drywall tight to the floor and carpet over it, the restorer will often recommend a cut so the plate and insulation can dry. When the wall is rebuilt, a small gap between the drywall and the slab, hidden by baseboard, helps the next time.

Many older homes in Topeka, Lawrence, Kansas City, Kansas and central Wichita have plaster over wood lath rather than drywall. Plaster tolerates brief wetting better than drywall because it has no paper face, but the lath can swell and the plaster can crack or let go of the lath. Firm, attached plaster that dries quickly can usually stay. Plaster that sags, bulges, sounds hollow or crumbles may need repair or replacement. Older plaster may also be painted with lead-based paint, so ask about lead-safe practices before any cutting ^[4].