What We Found Behind the Drywall
The contractor had cut the existing drywall four feet up from the floor across the front room, the bedroom, and one wall of the kitchen. That is roughly standard practice after flood or moisture damage. The cut line was clean and the studs behind it were exposed.
Naomi had wanted me to inspect everything before she had new drywall hung. Good call. The wood framing was generally sound but two studs in the front room showed termite damage, with the lower 18 inches partially eaten out. Not catastrophic damage, the studs were still standing, but they had lost meaningful structural value. We documented it with photos and she had a carpenter come in to sister new lumber alongside both damaged studs before drywall went back up.
The insulation in the wall cavities was a mix of old fiberglass batts (compressed, sagging, partially missing) and what looked like a previous owner's attempt to add foam board over plaster lath at some point in the 1990s. That whole layer was coming out. The contractor had already removed most of it. We pulled the rest by hand and bagged it.
The brick pier foundation under the shotgun was visible through gaps in the floor that had not yet been closed up. You could see daylight from underneath. That kind of ventilation is part of why these old houses survive humidity at all, but it also means whatever you put in the wall cavities is going to experience real outdoor conditions, not climate-controlled interior conditions. That changed our material choices.
Choosing the Right Drywall for a Coastal Home
The original lower drywall had been standard 1/2 inch white board with paper face on both sides. Paper-faced drywall is a mold buffet when it gets wet. Naomi had learned that lesson twice now. We were not going to do it a third time.
The choice for the replacement section was paperless mold-resistant drywall, sometimes called fiberglass-faced board. It is more expensive, roughly 1.7 times the cost of standard board at the time, but the fiberglass mat face does not feed mold the way paper does. If the wall gets wet again from a future event, the drywall itself will not become a mold source. The CDC guidelines on mold cleanup are clear that paper-faced materials need to be removed if they have been wet, so we wanted to eliminate that requirement.
The fiberglass-faced board is slightly different to work with. The face is more textured than paper drywall, which means you need a heavier skim coat to get a smooth finish before painting. We accepted that tradeoff. The installer who hung the board had worked with this material before and got it on the wall efficiently. The finishing was the part that took longer.
Mudding in Late November Louisiana Humidity
I had assumed November in New Orleans would be cool and dry. It was not. The week I was there, daytime highs were in the upper 70s with afternoon thunderstorms and dewpoints holding around 70°F. The house had AC running but the front room had two windows that did not seal properly and the indoor humidity in there hovered around 60 percent.
Joint compound at 60 percent humidity dries slowly. We did the tape coat on a Tuesday morning. It was still slightly damp Tuesday evening. By Wednesday morning it had cured enough to recoat, but barely. We were waiting on the compound the entire time, which extended the project by two days.
I had brought up a small dehumidifier from her storage room and ran it in the front room for the last three days. That dropped the humidity in there to around 45 percent and the final coats dried in something close to a normal schedule. If I had it to do again, I would have run the dehumidifier from day one instead of waiting.
The mud itself I switched to a setting-type compound (the 90 minute kind) for the first two coats. Setting compound cures by chemical reaction instead of evaporation, so high humidity does not slow it down as much. The third and finish coats I did with regular all-purpose compound for the smoother working consistency. That combination worked well in those conditions.
The Plaster-to-Drywall Joint
The most delicate part of the whole project was the horizontal joint where the new drywall met the original plaster above the cut line. That joint runs four feet up on every wall in the affected rooms, and it has to look invisible after paint or the whole repair looks like a patch.
Plaster and drywall move differently in response to humidity. Plaster is more rigid; drywall has slight flex. The seam between them is a recurring stress point that wants to crack. To handle this, we did a few things.
First, we ran a bead of acrylic latex caulk along the back of the joint where the drywall met the plaster, to give a flexible base. Then we taped the joint with paper tape and setting compound. Paper tape handles dynamic joints better than mesh because the bond to the substrate is mechanical-plus-adhesive rather than purely adhesive.
The coating sequence was setting compound for the embed coat, then setting compound again for the fill coat, then all-purpose compound for two finish coats. Each coat got slightly wider than the last, with the final coat about ten inches wide on each side of the seam. That wide feathering hides the slight surface texture difference between fiberglass-faced new board and old plaster.
After priming with a high-build primer (recommended by the paint store for transitions between substrates), the joint was visually invisible. Naomi has been back in the house for two and a half years and the joint has not cracked.
What I Would Do Differently
Two things I would change about how I approached this project.
First, I would have used the dehumidifier from the start. I lost two days of project time because I treated humidity as a background condition instead of a variable I could control. A 50 dollar a day rental from Home Depot would have paid for itself in saved time.
Second, I would have done a more thorough framing inspection before any drywall went up. The two termite-damaged studs we caught and fixed. But there might have been more issues we missed because we focused on what was visible from the exposed wall cavity. I would now recommend that anyone gutting a New Orleans home, even partially, get a structural inspection or at least a termite inspection from someone who can probe the framing properly before closing the walls up.
The total cost of the drywall portion of Naomi's recovery, including materials, contractor labor for hanging, my labor for finishing, and incidental tools, was around 3,400 dollars for three rooms. That does not include the floor work, the framing sistering, the painting, or any of the other recovery work. Drywall in a flood is never the most expensive part of the project, but doing it right matters because if it fails, everything you put back on top of it has to come off again.