Wet Drywall: Dry It or Replace It?

The short answer

Wet drywall can often be dried in place if the water was clean, it was caught within a day or two, and the board is still firm. It has to be replaced if the water was dirty, it stayed wet longer than about two days, or the board is soft, swollen, sagging or smells musty. The water source matters more than how wet it looks.

Start with where the water came from

• Clean water, like a burst supply line or an overflowing AC drain pan caught quickly: the drywall may be saved if it dries fast.
• Dirty water, like a washing machine or dishwasher drain, or clean water that sat for days: treat it as contaminated, and plan on cutting the wet board out.
• Sewage or floodwater from outside: wet drywall and insulation come out, every time. That is the standard the water-damage restoration industry works to.

In San Antonio the most common source is not the roof. It is the air conditioner: a clogged condensate line or an overflowing drain pan in the attic that soaks a ceiling slowly, often for weeks before anyone sees a stain. More on that on our water damage repair page.

Signs it has to come out

• The board is soft, crumbles when pressed, or has swollen at the bottom edge.
• The paper face has bubbled, peeled or separated from the gypsum.
• A ceiling is sagging or bowed between the framing.
• The insulation behind it is soaked. Wet insulation holds water against the board and will not dry in place.
• There is a musty smell or any visible mold.
• It stayed wet more than about two days. The EPA advises drying wet materials within 24 to 48 hours to prevent mold.

When drying in place can work

If the water was clean and caught fast, and none of the signs above show up, the wall can often be dried with fans and a dehumidifier running for a few days. Opening a baseboard or drilling small holes low in the wall helps air reach the cavity. Before anything is patched or painted, a moisture meter should read the board as dry, top to bottom. Paint over damp drywall and the stain, the smell or the mold comes back.

How far to cut

Water wicks up inside drywall well past the stain you can see. The cut goes above the highest point a moisture meter still reads wet, then up to a height that lets a full-width piece of new board go in cleanly. That makes a flatter, less visible repair than a ragged patch. Wet insulation in that section comes out too, and the framing is checked and dried before new board goes on.

A wet ceiling is a safety problem first

Soaked ceiling drywall is heavy and can let go without warning, especially under a bulging spot. Keep people and pets out from under it, turn off the lights and ceiling fan in that area, and if water is pooling in a bulge, catch it in a bucket before it brings the ceiling down. Then have the wet section taken down in a controlled way.

What we do, and what we do not

We cut out the damaged drywall, let the cavity dry, replace insulation where needed, then hang, tape, float, match the texture and paint so the wall looks the way it did before. For a large flood or standing water, a water mitigation company should dry the structure first; we handle the rebuild after. If you are filing an insurance claim, take photos of the damage before anything is removed.