Encapsulating wood with paint is often marketed as a mold-fighting miracle for new home construction. It's not. In this episode:
- Caliwel paint and how it’s supposed to work
- Active ingredients (hydrated lime) and their role in mold prevention
- Why using an encapsulant on wood during new home construction might not work.
- Problems paint encapsulation coatings create, including trapping moisture and failing
- How to prevent mold without using paint or encapsulation
The Mold Money Podcast
TRANSCRIPT
Iif you're one of those who understands there's no shortcut or easy fix for removing mold other than to remove it, meaning no treatment, no encapsulation is going to work, or be recommended as the normal course action.
And that when you're building a house, if you don't want it to grow mold, just build it so things don't get wet. Because treatments and encapsulation, you know, painting the wood when you build your house, that's not the answer.
Build your house so the wood stays dry.
If you get this, I'm going to save you the time of listening to today's show, which is about why encapsulating all the wood with a paint as you build your house is not the way to prevent mold, and it can cause new problems.
I'm going to be specifically speaking about a product that somebody asked me in my opinion about it, an encapsulation that they were told by an expert, you should paint all the wood in your house to prevent mold growth when you build in your house.
I'm going to tell you why this is not going to prevent mold and what new problems it can cause. FYI real quick too, paint can grow mold, not just wood.
In their logic, fear of the experts is that, quote, all biodegradable surfaces, every square inch of wood in a basement or crawl space needs to be encapsulated to make it unavailable to mold growth.
Because if it's unavailable to mold growth, the humidity can't be absorbed by the wood and it will be less concerned with relative humidity and mold. This is all garbage.
And also there will be settled spores on the wood when you paint it, no matter what. It's not sterile. So you are basically encapsulating the spores between your paint and the wood anyhow.
And if the wood gets wet, it's going to grow mold anyhow. This paint in particular, normally don't like to name brands. Next week it will be something different and people will be missing the point.
That's why I have to do so many of these. But it's a Caliwell Industrial Remediation First Choice Continuously recognizes the most effective antimicrobial, anti-mold treatment. That's what their website says.
It took me some time to break this down. It's fascinating how people can think of stuff in ways to prevent mold.
Because this product says, a specialty coating precisely engineered to offer long-term antimicrobial, anti-mold protection against odor-causing bacteria, mold, fungi, algae on a coating surface. You know, the drywall, the wood you painted with.
It uses calcium hydroxide, a natural occurring antimicrobial mineral, and it's effective against common microorganisms. Calcium hydroxide is actually lime, hydrated lime.
It's calcium with two O-Hs, oxygen and hydrogen molecules attached to it, which is interesting here. That means there's water availability if that breaks down. We don't want water for mold.
What's fascinating is also is calcium hydroxide, who would have thought, is affected by not just moisture, but carbon dioxide.
That's the same CO2 global warming gas that people blame global warming on, the same carbon dioxide you exhale, and the ones plants use to make oxygen.
So there was a deep investigation into why Biosphere 2, the one that they tested to see, could we live on Mars in a closed environment where plants inside this dome regenerate our carbon dioxide into oxygen? Well, it quit working.
They had to actually eventually pump oxygen into the dome and eventually just call it quits. They couldn't keep up with making oxygen no matter how many plants they had.
What they discovered was that the calcium in the concrete reacted with the carbon dioxide in the air. Basically, the concrete sucked the CO2 out of the air, so it wasn't available to the plants.
The investigators did a great job of then actually cutting into the surface of the concrete in the biosphere and seeing that, yes, it was carbonized by the process of the CO2 reacting with the lime in the concrete.
So, what does this mean for using it to prevent mold?
Is, over time, the hydrated lime is going to be neutralized by the moisture in the air, the same humidity that's intended to keep away from the wood, and the carbon dioxide, which you can't get rid of. Carbon dioxide is in the air everywhere, right?
The way that the lime prevents mold is, in theory, it raises the pH of the surface, and molds don't like the high pH level, so they can't grow as fast, or even grow again.
But then if over time the moisture and the carbon dioxide break the lime down, then you can get back to it not working. So the general idea is a high pH from the lime is said to inhibit mold growth by making surfaces to outline for spores.
This is not bulletproof. Mold is an adaptive, resilient organism. The only way to prevent mold is to keep things dry.
Another common one I hear is, what does mold need to grow? Food, air, oxygen, and water. It doesn't even need air.
It can complete its metabolism. This is why if you pull a piece of OSB board that's wet apart, behind the flakes, it's never ending. Pull another flake off, there's mold on the back of that flake.
There's no air back there. How did that happen? It only needs a small amount of oxygen, not air, to complete its metabolism.
And if it needs to, it can go without it. Let's say it prevents most of the mold without throwing the baby out with the bathwater. Also, real quick, it claims to be EPA registered, and it is.
But it's a little misleading because it's registered as an anti-microbial, not a fungal side. Here's the difference. An anti-microbial is any substance that's designed to kill or inhibit microorganisms, bacteria, viruses, fungi, algae.
So therefore, all fungicides, those products specifically tested, marketed to prevent mold, fungus.
They are by default all anti-microbials, but not all anti-microbials are fungicides, meaning this product is not technically that bulletproof as a fungicide.
So I had the thought, having said all this, that maybe the company came up with a way to prevent the moisture and CO2 from making their product less effective, because they say they have some patents.
Here are some ways that maybe here's what they did. But over time, it basically none of this is really going to, but all of this is really difficult and not likely that they did.
One would be to embed the lime particles inside a polymer matrix, an acrylic and epoxy coating, which seems like maybe one thing they might have done.
But over time, these CO2, the carbon dioxide molecules, are still going to diffuse through polymers. And the moisture vapor permeability is going to be reduced. All this paint is reducing how fast you would in dry.
Therefore, you're going to trap moisture if it gets wet. Another way is to encapsulate the lime particles in a kind of a shell, which could create maybe a controlled release effect and prolong the alkaline environment.
That would be kind of expensive, and eventually, it would still degrade over time. A real quick one you may have thought of is a scavenger, meaning let's put a carbon dioxide absorbing compound into it, kind of like when you open one of your...
If you're a backpacker, you open a bag of freeze-dried food, and you seal a packet in it, it's to absorb oxygen. Then same thing, scavenger capacity is finite. It's just prolonging things.
And another one, last one would be to apply a hydrophobic top coat over the lime layer to reduce the water vapor and CO2 penetration, which again is going to reduce the breathability of the surface and trap moisture behind it.
There are some applications where this has been done. Some high-end antimicrobial paints will include these alkaline components, and certain cement products will also do it. Similar to the biosphere, concrete's been around a long time.
The biosphere is probably not the only building that had this issue. Biosphere people probably didn't know that there's a solution to it, kind of.
The concrete's still subject to carbonation, so there's pretty much no widely available or known lime-based mold product that's going to be fully carbonation-proof. Well, I wasn't finished thinking about this. This is how I think.
The thought never leaves my head. Somehow, I mean, it leaves, I think it leaves, but I keep thinking of... In the morning when I'm drinking my coffee, something will pop into it.
It's how my brain works. I noticed on the website the letters TDS. Stands for Technical Data Sheet.
But I didn't see on the website anywhere a TDS sheet. I had to go look for it. When I found it, it listed the, what you must do when you apply it.
The technical data sheet, here's how you're supposed to use it.
You're supposed to put down an acrylic primer first and then put two coats of the lime-based product on it, which would mean you paint all the wood in your brand new house before you, when you're finished framing it three times.
But why do I put an acrylic primer down first and then two coats of lime paint? How come I can't just put down the paint? It probably comes back to, they can't really put it right on the surface because wood inherently has some moisture.
Wood is normally not completely, completely dry. It absorbs a little bit of moisture from its environment. And this is what these people worry about and why they do it.
I'm like, no, wood normally like in the forest, absorbs a certain amount of moisture and then it stops. It reaches equilibrium someplace between 10 and 15 percent. It might be normal to find 12, 13, 14, 15 percent moisture content of your wood.
It won't go to 17 percent. It won't go to 19 or 20 percent, which is wet. And that's what I don't think people understand, is it's normal.
Mold can't grow. That water is not available for mold growth. It's locked up between the cells of the wood.
So one last thing, the primer required introduces a new problem. Remember I told you paint can grow mold. We've all seen paint grow mold, and you put in an acrylic primer on there.
The company recommends just any generic acrylic primer. It's not saying an antimicrobial primer. You basically painted your wood with normal paint that can support mold, which is going to trap moisture, not allow it to dry out fast enough.
If mold grows now, here's the real kicker. If you look at the safety data sheet for lime, when it's painted, it's a liquid. You're not going to have this hazard.
But dry lime powder is really hazardous to breathe. So imagine now your house grows mold anyhow. How are you going to get rid of the mold?
You're going to sand, bead blast, the paint, the moldy paint, the moldy wood. You're going to have hazardous lime dust all over your house. And I've only begun to start thinking about this.
There's so many potential issues, problems that could cause. And let's say, hypothetically, those are, if you want to use the term, is it likely, is it probable? Is it likely?
It's possible. Let's say you say, well, anything's possible. I'm going to do it.
It won't prevent mold. If something gets wet, mold's going to grow on it. It's just a matter of time.
The other thing that's not considered here is you're painting this after the framing's up. If you really want to do it properly, you'd have to do like a good home builder before he puts the fascia on the roof.
You prime all six sides of the wood after you cut it, before you nail or screw it on to the house. Because otherwise, you're missing, you're not going to be able to paint the corners.
And when they get wet, they're going to absorb water into the piece of lumber through the corners. And that's going to be not be able to dry out because you painted all the other four sides.
So the solution to build a house that won't grow mold is don't allow it to get wet. Build it so water can't get in. Plan for failure.
Design it so when something gets wet, it can dry out. My books, What Your Builder Should Know and How To Build A Healthy Home Go Through This, are some caveats. They're really important to understand in terms of flashing the windows properly.
Nobody flashes windows properly to keep the water out. And then with the new buildings, I like to pump in the fiberglass and the cellulose. I love cellulose, but they pack it like a mattress.
Unlike old traditional fiberglass bath that was loose and fluffy, that insulation like fiberglass bath or rock wall bath allows some air movement for the wall to dry out if it gets wet.
When you pack it like a green building does for better insulation, I like the idea of better insulation. Lower utility bills warm a house, but then it gets wet.
It can't dry out and you don't even see it until the wood starts to rot because the water can't drip inside as easily and go, oh, the window is leaking. It's kind of stuck behind all that packed insulation rotting out the outside of your house.
You don't see it until you go, oh, let's take it apart on the outside because you can't take it apart on the inside. It's a huge mess. All the insulation, the fluffy packed insulation will have to fall out.
The bad insulation is kind of better for that. As the mold expert, I'm just telling you for fact, that insulation allows for things to dry better.
And I'm telling you as a fact, it's highly probable, highly likely that you as a builder or your builder are flashing the window incorrectly. If you're one that flashes the windows correctly, send me a screenshot and photos to you.
One in a hundred thousand or more. Thanks for listening. Till next time, I'm Daniel Stih.
Certified by ACAC • 20+ Years Experience • Author of Mold Money