Structural drying in humid Louisiana houses

Drying is a balance between three things: air movement, humidity and temperature. Wet materials release moisture into the air right at their surface. Air movers push a fast, steady stream of air across that surface so the damp layer is constantly swept away. Dehumidifiers then pull that moisture out of the room air and send it down a hose as water. Warmth speeds the whole process because water evaporates faster from warm materials.

If any one of those is missing, drying stalls. Fans without dehumidification just move water from the floor into the air, where it soaks back into drywall, furniture and ceilings. Dehumidifiers without air movement dry the air but leave a damp layer clinging to every wet surface. That is why a drying setup looks the way it does: air movers angled along walls and under cabinets, and one or more dehumidifiers sized to the volume of the room and the amount of water involved.

Two main types of dehumidifier are used. Refrigerant units cool air over a coil so water condenses and drains away ^[2]; low-grain refrigerant models are designed to keep working as the air gets drier. Desiccant units pass air over a moisture-absorbing material and work well in cooler spaces and for dense materials such as hardwood and concrete. Specialized tools, such as injection systems that push air into wall cavities or mats that draw water up from hardwood floors, are added where ordinary airflow cannot reach.

The work is guided by measurement. Restorers following the ANSI/IICRC S500 standard set a dry goal for each material, usually based on readings from unaffected parts of the same house, and record readings every day until the goal is met ^[3]. Equipment comes out when the numbers say so, not when the surface feels dry.

Air can only hold so much water vapor, and in south Louisiana it is often close to that limit. When outdoor air is warm and humid, opening windows brings more moisture into the house than it carries out. That is the opposite of what drying needs, and it is why restorers here usually seal the house and dry it with dehumidifiers in what is called a closed drying system.

Air conditioning helps, but only up to a point. A central system removes some moisture as it cools, but it is not designed for the volume of water a flooded room releases, and running it hard while ducts or the air handler are wet can spread odor and moisture through the house. Contractors often ask homeowners to set the thermostat to a moderate temperature and leave the rest to the drying equipment.

Building methods also matter. Many Louisiana homes have vinyl wallpaper, oil-based paint or vinyl flooring that slow evaporation from the surface. Kitchens and bathrooms have cabinets sitting on toe-kicks that trap water underneath. Slab homes hold moisture in the concrete for a long time. Each of these needs its own technique, and a one-size setup of fans in the middle of the room leaves them wet.

After the first setup visit, the contractor usually comes back once a day. They take readings from the same marked spots, write them down and compare them with the dry reference. Areas that are dry have equipment moved away from them; areas that are slow get more airflow, a different angle or a specialized tool. A visit may only take half an hour, but those numbers are the proof that the house is dry.

Ask to see the drying log. It should show the date, the location, the material, the reading and the dry goal for each spot. Insurers often ask for it, and it protects you if a problem shows up months later. If a contractor cannot show readings, you have no way of knowing whether the house was actually dried.

Most clean-water jobs in a house take several days of equipment time. Larger losses, dense materials such as hardwood and concrete, and humid weather can stretch that. When drying is complete, any materials that were removed can be replaced, and rebuilding can begin.

Slab homes, common across postwar suburbs like Metairie and Kenner and in most newer subdivisions around Baton Rouge, hold water in the concrete and push it up into flooring and wall plates. Drying them means lifting vinyl plank or laminate where water got under it and running dehumidifiers long enough for the slab to give up its moisture.

Raised homes, such as the shotgun and Creole cottages of New Orleans, dry differently. Water drains through floorboards into the space below, and the floor framing can be dried from above and below at the same time. The catch is the crawlspace: if the ground underneath stays wet, it keeps feeding moisture into the floor, which is why crawlspace drying is often part of the job.

In north Louisiana, around Shreveport and Bossier City, the air is somewhat drier in cooler months, and open-air drying can sometimes help. Summer there is still humid, though, and closed drying remains the default for most of the year.

Hurricanes create the hardest drying conditions there are. After Hurricane Ida in 2021, more than a million people in Louisiana lost electrical power, many of them for days ^[6]. Without power, dehumidifiers and air movers cannot run, and wet houses sit closed up in late-summer heat while every contractor in the region is booked.

In that situation, the priorities change. Getting wet carpet, pad and soaked drywall out of the house matters more than ever, because those materials hold the water that feeds mold. Some contractors bring generators to power drying equipment; if anyone runs a generator, it must stay outdoors and well away from doors and windows, because carbon monoxide builds up quickly indoors ^[7].

When power returns, drying can start in earnest, but the house may already have been wet for several days. Expect the contractor to remove more material than they would after a quick response, and to look closely for early mold growth before they set equipment. Photograph conditions before anything is removed; the timeline will matter to your adjuster.

Some water does not respond to air movers in the middle of the room. Wall-cavity injection systems push dry air through small holes into the space behind drywall or under cabinets, drying the cavity without tearing the wall open. Floor drying mats sit on top of hardwood and use suction to draw water up through the boards. Heat drying, using indirect heaters in a contained space, raises material temperature so water moves out faster, and is sometimes used on dense materials once the room is sealed.

These tools are not needed on every job, but they often make the difference between drying something in place and tearing it out. If your house has hardwood floors, plaster walls, tile over a wood subfloor or built-in cabinetry, ask the contractor which of these they would use and whether they have them available.

Ask what the dry goal is for each material and how it was chosen. Ask how many dehumidifiers and air movers they plan to use and why. Ask whether they will lift flooring or open walls, and what will be replaced afterward. Ask how often they will take readings and whether you can have a copy of the drying log. And ask what they will do if an area is still wet after a few days.

If you have flood insurance as well as a homeowners policy, ask whether they have documented the job in a way that separates damage from each cause. In Louisiana, where storms bring both rain through the roof and rising water from outside, that separation often matters to the claim. Our insurance adjuster guide explains why.