How the Damage Happens
The wax ring is this donut-shaped seal between the bottom of your toilet and the drain pipe in the floor. It keeps sewage gases and water from leaking out. They last a long time, usually 20 to 30 years according to most plumbing sources. But they do fail, and when they do, water seeps out slowly with every flush.
In my case, the water was running along the floor and wicking up into the drywall behind the toilet. The floor tile looked fine. No visible puddles. Just this slow, invisible migration of moisture into the wall.
My buddy Steve, who does plumbing work, told me later that wax rings fail more often when toilets rock even slightly. Mine had a tiny wobble I'd never noticed. He said even a fraction of an inch of movement can break the wax seal over time.
Signs You Might Have This Problem
Soft or spongy drywall behind the toilet. Discoloration or staining near the floor line. A faint sewer smell that comes and goes. The toilet rocks when you sit on it. Water stains on the ceiling below a second-floor bathroom. Any of these should send you investigating.
Pulling the Toilet
You have to pull the toilet. I know. I spent two hours trying to figure out a way around it. Watched videos of people cutting drywall patches to fit around the toilet base. Thought about just replacing the bottom six inches of wall and leaving the toilet in place. None of it made sense.
Pulling a toilet is not as bad as it sounds. Turn off the water supply valve behind the toilet. Flush to empty the tank. Sponge out whatever water is left. Disconnect the supply line. Pop the caps off the floor bolts, unscrew the nuts, and lift straight up. The toilet weighs maybe 50 to 60 pounds. I set mine in the bathtub on an old towel.
The old wax ring looked exactly like you'd expect. Flat, cracked, and pushed to one side. The flange underneath had some corrosion but was still solid. Rob came back over to take a look and confirmed the flange was fine. "If the flange is cracked, that's a different project," he said. Mine wasn't, thankfully.
Assessing the Drywall Damage
With the toilet out of the way, I could finally see the full extent of the damage. The bottom 10 inches of drywall behind where the toilet sat was soft and discolored. There was no visible mold, which was a relief. But the paper facing was bubbled and the gypsum core felt like wet chalk when I pressed on it.
I checked with a moisture meter I'd borrowed from my sister-in-law Laura (she flips houses as a side gig and has every tool imaginable). The wall read about 35% moisture content. Normal is under 1% for drywall. So yeah, it was soaked.
The good news was the damage was contained to a roughly 14 by 10 inch area. The studs behind it were damp but not rotten. I pointed a box fan at them for two days before doing the repair.
The Actual Repair
Once the framing dried out, the repair itself was pretty standard patch work. Cut out the damaged section with a drywall saw, going to the center of the nearest studs on each side. I used moisture-resistant drywall for the patch piece. It's the stuff with the green paper facing. Costs about $4 more per sheet than regular drywall but it makes sense for a bathroom wall that sits inches from a toilet.
Cutting and Fitting the Patch
The awkward part is working in that tight space. Even with the toilet removed, you're still dealing with the supply line stub-out, the floor flange, and the wall angle. I cut my patch piece about three times before getting the fit right. Measure twice, cut three times apparently.
I screwed the patch into the studs with drywall screws every eight inches or so. Used paper tape on the seams because Uncle Frank has permanently convinced me that mesh tape is the devil's product. Two coats of all-purpose joint compound, sanding between coats with 150-grit. The whole finishing process took three days because of dry time.
Priming and Painting
I primed with Kilz mold-resistant primer. Two coats. Then matched the existing paint as close as I could. The bathroom hadn't been painted in six years so the match wasn't perfect, but behind a toilet? Nobody's inspecting that wall with a flashlight.
Resetting the Toilet
New wax ring: $6 at the hardware store. I went with the extra-thick version because Steve recommended it for toilets with any history of rocking. Pressed it onto the flange, lowered the toilet straight down onto the bolts, and tightened everything up. Sat on it and rocked side to side. Solid. No wobble.
Turned the water back on, flushed five or six times, and checked around the base with paper towels. Bone dry. That was three months ago and it's still dry.
What It Cost Me
Here's the breakdown. Moisture-resistant drywall piece (I bought a 2x2 foot section they had pre-cut): $9. Wax ring: $6. Joint compound (already had a bucket but figure $12 if you need to buy one): $12. Paper tape: $4. Kilz primer: $14 for a quart. Drywall screws (small box): $6. Sandpaper: $5. Paint touch-up (sample size): $8. That's $64 if you start from nothing, or about $95 if you add the stuff I already had on hand.
Rob spent $1,200 because he paid a plumber $350 to pull and reset the toilet and a handyman $850 for the drywall work. Both are reasonable rates. Sometimes paying someone makes sense. But for a small patch behind a toilet, this is pretty approachable DIY work if you're comfortable pulling a toilet.
Mistakes I Made
I should have checked for this problem way earlier. The toilet had that tiny rock for at least a year. If I'd shimmed it and tightened the bolts when I first noticed, the wax ring might have lasted longer and the water damage wouldn't have happened.
I also should have worn a respirator when cutting out the wet drywall. It didn't have visible mold, but the CDC recommends respiratory protection when working with any water-damaged building materials. Laura reminded me of that after the fact. She was not impressed with my safety approach.
And honestly, I should have just bought a full sheet of moisture-resistant drywall instead of the pre-cut piece. The pre-cut cost $9 and a full 4x8 sheet costs $16. Math-wise it would have left me with extra material for future bathroom repairs. Lesson learned.