Coating Interior Doors to Resist Flood Damage

Replacing bedroom and closet doors and trim after a flood accounts for a large portion of homeowner insurance claims. What if a simple coat of paint could save them from ruin?

Looking at the huge piles of debris resulting from Hurricanes Helene and Milton in Florida, you find a recurring theme: vast amounts of trim and interior doors. Not only is this a huge environmental waste, it might be preventable. 

The type of flood event you might encounter should inform your paint choice.  A home that’s impacted for a few hours from a storm surge might get by with a less costly paint treatment than one that’s from river rise, soaking for a week or more.

Let me also add a note about the type of materials used for doors and trim. Try to avoid medium density fiberboard (MDF) and other forms of “engineered” wood. These products may not have the same forgiveness factor as natural wood. 

That being said, when a product claims to be “all wood,” dig a little deeper. I’ve seen older doors identified this way that have hollow cores packed with sawdust. You don’t find out until the door floods and swells up to twice its thickness. Look for the words “solid sawn,” rather than “all wood” in the door description.

I would also avoid finger-jointed trim. The finger joints, once wetted, become weak and unstable. They can also trap bacteria between the fingers. They’re less forgiving than solid-sawn lengths of lumber.

Let’s look at some water-resisting paint options you can use to coat, from good to best to extreme. In all cases, all four surfaces of the item need to be coated.

Good: Semi-Gloss or Gloss Acrylic Paint

Acrylic paints are water resistant, not water proof. That means they’ll keep moisture at bay for a while, but they’re also vapor permeable. This quality is right for many surfaces because it allows the material behind it to dry. That’s why building scientists recommend them over non-permeable coatings for things like the exterior of a stucco house. You don’t want the paint to trap water behind it, blister and peel off after a period of heavy rain or high humidity. 

For interior doors and trim, choose this option if your only real risk is a sudden and short-lived flood event, such as a flash flood. It might protect for an hour or two, probably not for a 12 hour submersion. You will probably need two coats on top of preprimed wood, three if the wood is unprimed. I’d choose this coating for a home that lies on the edge of a flood zone, not in it, or if your neighbor’s house flooded last years, and you had a narrow miss, as streams rose.

Better: Epoxy “Pre-Catalyzed” Coating

If your home lies in a flood zone, or you’ve had a previous flooding event, your first choice could be an off-the-shelf epoxy paint. It’s semi-waterproof, and may give you the protection you need for a few hours if your interior gets knee-deep in flood water. 

The brand I’ve suggested is just my personal choice, not a sponsored product. From an economic standpoint, this might be the most affordable option. A gallon of Behr’s White HP Pre-Catalyzed Waterborne Epoxy Semi-Gloss Interior/Exterior Paint runs for under $50 at your local box store.

The term “precatalyzed” means that the chemical that causes the paint to dry and harden quickly has already been added to the mix.

The fact that it’s waterborne makes it less toxic for indoor air, easier to clean up and apply, but it’s probably not going to last as long as a commercial epoxy. On the other hand, it goes on easy, and if you’re dealing with more than a few hours of flood submersion, you may have a lot of other material problems with your home’s structure, flooring and mechanics. 

Best: Two-Part Epoxy

Maybe you live at the edge of a river in a concrete block home, and floods are just a way of life, whereas moving or raising the house is financially beyond you. It might be worth spending the $200 bucks to get a couple of gallons of commercial, two-part white epoxy. 

This product is quite pricey, at about $125 per gallon, but that’s the cost of one wood panel door for a bedroom. 

My recommendation would be to mix the two parts in small batches, with one-to-one portions in equal sized measuring cups. Make sure you have a clean dry place where you can leave all of the pieces to dry for 24 hours or so. Most epoxies I’ve used say they dry quickly to the touch, but full setting takes at least a day. 

Extreme: Water-Based Marine Coatings

I’ve been around boats much of my life, so I know there are products designed to go under. Most, however, are too toxic for home use. I wouldn’t put traditional antifouling paint inside my home. It contains copper and isn’t designed to be in contact with people.

On the other hand, some of the new, more eco-friendly versions of these coatings might be worth a look. For example, this water-based product claims to have reduced VOCs and low odor. It might be worth testing it on a few pieces of trim.

The advantage of a marine paint like this is that it includes biocides—meaning it’s designed to kill things that want to grow on it. 

I’d want to make sure the finished product dries fully, and is not chalky or likely to rub off when a dog or a kid touches it. You might test it in the garage or a shed before you commit to using it anywhere indoors.

Caveat: Paint is Not Bulletproof

Paint and coatings can only do so much to save your home’s wooden components. I’ve offered these options as suggestions, not guarantees. Depending on the specifics of your flood event, they may not hold up to the salt, bacteria, long-term submersion or other factors. 

Best practice is to try to get your house up above likely flood pathways, follow FEMA guidelines, and clean up immediately after any flood event. Time is your enemy after a flood. The right paint may buy you a little more of it.

The CPT-based paint kept the housings of the COD sensor and the Chl <em>a</em> sensor clean for over 4 months. In addition, the paint prevented fouling of the BOD sensor housing even after 6 months of seawater immersion. camptothecin (CPT, isolated from plants such as  Camptotheca acuminate, Nothapodytes nimmoniana, Pyrenacantha klaineana, and P. volubilis and previously known for its antitumor activity) exhibited effective antifouling activity in laboratory tests and field experiments.