Water damage to drywall can happen slowly. At my house, there was ceiling damage from a roof leak. Or it can be a surprise, like the pipe that sprayed water inside the kitchen wall.
Fortunately, I learned that most drywall repairs can be easily done. In this drywall water damage repair guide, I’ll talk about how to make repairs and the experience my family had.
| Project difficulty: Intermediate Estimated time to complete: 1 week to 10 days (including the drying and the repairing itself.) Project cost: DIY costs range from $100 to $400 for minor damage, but costs can increase depending on how extensive the damage is. *Before repairing the wall, make sure the cause of the water damage is addressed. If it is a leaky pipe, for example, make sure to get it fixed before repairing your wall. |
How Does Water Damage Drywall?
Drywall is made of gypsum, which absorbs water. It’s sandwiched between two paper panels, which also absorb water. If it’s wet for long stretches, the drywall will eventually come apart.
Why You Shouldn’t Ignore Drywall Damage
Soaked drywall can be dangerous to you and your home. Here’s why.
- It loses structural integrity: As mentioned, wet drywall eventually will come apart. So your ceiling may come down, as may your shelves. Or eventually, the wall itself will fall apart.
- Electrical issues: Your home’s electrical lines run through the walls, covered by drywall. Wet electrical lines increase the chances of a fire. If wiring is near a leak, turn off power at the circuit breaker.
- Mold: Wet drywall, with its small crevices, is the perfect home for mold to flourish. It can create health problems for you and your family or worsen existing illnesses, like asthma.
See Related: Health Risks of Mold in Your Home
How to Repair Drywall Water Damage
Before you can fix the drywall, you have to find the damage (or the extent of it), then find the source of the water and stop it.
How to Spot Drywall Damage
Some water damage will be easy to see. Others may take some sleuthing.
- Stains: You’ll likely see a coffee-colored stain on your wall or ceiling. (That’s how we discovered the roof leak.)
- Bubbling or wrinkling wallpaper or paint: This happens when the drywall’s paper backing gets wet.
- Moisture on the walls or around baseboards: A pipe leak can send water down the walls, or there may be leaks around your windows or your home’s foundation.
How to Find the Water Source
In some cases, the source will be obvious: Flooding from a storm, a sewer backup, an overflowing bathtub, or a major pipe break.
Other sources won’t be as obvious. In my case, I heard hissing in the kitchen. It took me a few minutes to figure out that the noise was coming from inside one of the walls.
Other places to check, depending on where the damage is visible:
- Around the toilet, or pipes under the sink
- The roof, for missing shingles
- Window air conditioners or fans
- Outside walls for cracks or other damage
- Areas of standing water
Be aware that tracking a leak can be tricky. Water travels: It can enter a roof or wall at one spot, but the damage will show up far from the leak.
Removing Damaged Drywall
This will depend on the amount of damage, but your first step will be to inspect the distressed areas. Remove drywall that’s:
- Cracked
- Soggy or crumbling
- Bulging
- Moldy
If you’re removing a large piece of drywall, put safety first. Turn off the power at the main switch or circuit breaker. (You don’t want to saw into a live wire.) Also, remember to remove any outlets and switches on the wall. Then:
- Mark a straight line above the wall, just above where the watermark ends
- Cut about three-quarters of the way through the drywall with a utility knife
- Loosen and carefully remove the piece of drywall.
- Remove any insulation in the area; it’s likely wet, too.
For a smaller area, cut a square or a rectangle shape around the damage. This will make it easier to create a replacement patch.
My Tip: In the course of repairing leaks (or having them repaired) you may end up with extra holes in the wall. With our pipe leak, the plumber cut a hole in the kitchen wall and then found he couldn’t access the broken bit of pipe. He had to cut a hole in the adjacent room to reach it.
If that happens, just hold on to the cutouts. You can use them to measure new patches, or you may be able to put them back.
Dry Out The Areas
Once the damaged portions have been removed, it’s time to dry out the area around and inside the wall. You can use a regular fan or dehumidifier, or rent a high-efficiency blower for a larger job. Whatever you use, let it run from three to five days.
You might have to be creative in getting air to the walls. Our kitchen pipe leak occurred in a small section between the kitchen and pantry. The only access hole was near the ceiling — setting up a fan would be difficult, and it wouldn’t dry the bottom section.
Our handyman’s solution was to cut a 9-inch by 19-inch hole in the bottom of the pantry wall. We removed a shelf and cleared floor space for a box fan, which we let run for a few days.
How to Replace Drywall
Now it’s time to install the new drywall:
Cut and Install the Patch
- To begin, measure the hole that you cut around the damaged area. This way you’ll know how large of a patch to cut. If you plan to screw the patch into the studs, make sure it’s large enough to rest the edges on the studs.
- For large patches, you may need to install a support, using 3-inch scrap lumber or 3/4-inch plywood. Cut the support 2 to 4 inches longer than the hole you’re patching. Place the supports behind the drywall, then screw them in.
- Size-test the patch to make sure it fits snugly. (Don’t force it in.) Drill pilot holes in the studs, then attach the patch.
Another option is to use drywall clips, which help support the patch. Follow the manufacturer’s instructions on how to install the clips and patch.
Cutting drywall can produce a lot of dust, so consider safety goggles and a mask.
Tape and Mud the Patch
Tape and mud is the process of applying drywall tape and joint compound to hide the drywall seams. Here’s how:
- Apply drywall tape (either fiberglass mesh or paper) to the seam. For large patches make sure it’s centered over the seam. Smooth the tape down to secure it.
- Use a drywall knife to spread about an inch of joint compound over the tape. Go over it again with the knife to remove excess compound. Wait 24 hours to dry.
- When the compound is dry, sand it smooth, then apply another coat of joint compound. Let it dry for another 24 hours.
- Sand the now-dry compound again and clean the surface with a tack cloth.
- Time to paint! For new drywall, put down a coat of primer before applying wall paint. New drywall is very porous: It will soak up the wall paint, leaving an uneven finish.
Replacing the Cut-Outs
In some cases, like mine, you may not have to cut drywall. The kitchen leak left us with three dry, solid pieces of drywall that could go back into the wall.
Normally, they can be reset using the same techniques as applying new drywall patches. But luckily, the smaller pieces fit snugly, so our handyman just needed to give them a few easy taps, and then finish all three with drywall tape and joint compound.
Since the repaired walls were already painted, we skipped the primer and just put on a coat of paint after sanding. (And thankfully, we had leftover paint from all three colors!)
Painting Water-Stained Drywall
If the damage to your drywall isn’t severe enough to need replacement, painting over the stain is an option.
That’s how we repaired the ceiling damage from our roof leak. We waited several days after the roof repair to be sure the site was dry and the drywall was solid, with no sign of mold. Fortunately, the paint had not bubbled, so we didn’t have to scrape the loose bits.
Experts suggest using a coat of primer to keep the stain from bleeding through. I confess that I just applied two coats of paint, and so far, it’s held up.
When You Need Professional Help
There are times when you may need to have an expert’s help before you even consider repairing damaged drywall:
- Sewage backup: Sewage can carry bacteria, viruses, and parasites that cause illness. If at all possible, call a local expert who can handle biohazard cleanup.
- Floods: Floodwater can carry debris and dirt as well as bacteria. Plus, there could be electrical or other hazards. Even if you’re doing your own cleanup, the EPA suggests getting professional help to determine if it’s safe to go in the house.
- Mold: Large amounts of moldy drywall (roughly larger than 10 square feet) can be toxic, and should be removed by experts.
See Related:
With luck, your home may never have drywall damage. But I hope our guide has given you the confidence to tackle that repair should it be needed.
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