PETERSBURG, FLA. — When David Jablonski began renovating and expanding his 2,500-square-foot home, he made a decision that set his house apart from most of his neighbors’: he replaced standard drywall, plywood, and insulation with non-toxic, moisture-resistant materials. He didn’t know at the time how soon that choice would be tested.
A Different Approach to Renovation
The renovation, which added 1,400 square feet to the home, reached occupancy in May 2024. In place of gypsum drywall, exterior plywood, and OSB, the project used magnesium oxide (MGO) board — a material still unfamiliar to many contractors and building inspectors. Behind the walls, ceilings, and floors, crews applied a mineral-based treatment meant to keep studs and cinder blocks free of lingering odors after water exposure.
City inspectors, unfamiliar with MGO board, had questions during permitting. Jablonski recalls one inspector examining a stack of boards that had sat outdoors for six months, finding no sign of decay. Once satisfied the materials were built for flood resistance, inspections moved quickly and the project passed.
Two Hurricanes, One Mostly Dry House
The real test came a few months later. On September 27, 2024, Hurricane Helene sent roughly four feet of floodwater into the home. When Jablonski returned three days after the storm, the house was largely dry, with only minor seepage — a result he attributes in part to water-resistant board on the floors drawing moisture out of the concrete slab below.
Twelve days after that, on October 9, Hurricane Milton brought about six inches of water into the house. This time, the floors were dry within a day. In the newer addition, crews removed the lower four feet of wall board and insulation as a precaution; when they did, they found no odor or staining — a contrast, Jablonski says, to seven earlier floods at the property that had left walls discolored and smelling of mildew. Helene and Milton brought the home’s lifetime flood total to nine.
Refining the System After the Storms
After the two storms, the renovation shifted to an updated set of materials, including a thicker, insulated wall panel rated for mold, fire, and moisture resistance, run four feet up the walls throughout the house. The remaining plaster was replaced with MGO board installed a full eight feet high, and MGO board was also used for the roof sheathing.
Paint, primer, screws, and adhesives followed the same standard, chosen for non-toxic and mold-resistant properties over conventional alternatives. Jablonski says the household now experiences no lingering odor after flooding — a change he credits to the shift in materials. Sewage-contaminated insulation had to be discarded, though he notes freshwater flooding would have allowed it to be reused; roughly 600 square feet of MGO board was salvaged and reused after the storms.
Designed for the Next Flood
The renovation was built around the assumption that more flooding is likely. Jablonski expects future floods will require only carpet replacement, with walls needing nothing more than a wipe-down. The approach was informed by George Swanson of Austin-based Swanson Associates, who specifies non-toxic, flood-resilient materials for homes prone to water damage — including installing the MGO board with a one-inch gap above the floor line, concealed behind base molding, so the wall assembly can breathe and floodwater has somewhere to go.
In sections where old walls came out entirely, the crew skipped traditional wood framing. Panels were screwed directly into the cinder block to form the supports, producing a wood-free exterior wall assembly in the renovated areas.
What Other Homeowners Can Take From This
Jablonski’s experience points to a few practical lessons for anyone building or renovating in a flood-prone area: material choice affects not just how a home looks, but how it recovers after water intrudes; leaving room for airflow and drainage can matter as much as waterproofing itself; and the materials worth paying more for are often the ones that shorten the cleanup, not just the ones that resist damage outright.
This account is based on the experience and observations of homeowner David Jablonski, as described in correspondence regarding the renovation.
Image for illustrative purposes only.