Fire Proof Paint makes so much sense!
On a recent show of Paint Misbehavin on TLC they introduced a paint called Inferno which you can paint your home with to protect it from any possible fire. The paint looked like it actually built a char when fire was applied to it which prevented the heat and flames from penetrating to the bare wood behind it. They used all sort of flame throwers to test it and nothing got through. With a paint such as this I was thinking that it would make a lot of sense to paint my house to prevent such a catastrophe.
My question is, has anyone used this product? as I am really thinking about adding this to my home here in Santa Barbara.
It only makes sense if you're operating under the misconception, as you appear to be, that flames have to touch the wood before that wood will start to burn. That is, fire proof paint on a wall equals a fire proof wall. Sorry, but that just isn't true. Fire proof paint only means that the PAINT on the wall won't burn. The wood inside the wall will burn regardless of what kind of paint is on those walls if it gets hot enough.
"Burning" is a chemical reaction between wood (cellulose) and oxygen in the air. The cellulose, in turn, is nothing more than sugar molecules produced in the leaves of the tree from photosynthesis and stacked up like bricks by the plant making the glucose. There are in fact two different kinds of sugar (glucose) molecules; glucose a and glucose b. If you stack one kind of sugar molecule up like bricks, you get cellulose, which is what wood is mostly made of. If you stack the other kind up like bricks, you get starch, which is what potatos and rice and cereal grains are made of. In fact, since plants can only produce sugar molecules by photosynthesis, everything in every plant started off as a collection of sugar molecules. And, even those fungii that eat wood, like the wood rot fungus Serpula Lacrymans are acutely aware of the importance of sugar to life on Earth. When wood rots, the Serpula Lacrymans fungus is simply recycling the sugar molecules that the cellulose is made of for use in it's own metabolic processes. That is, it eats wood for it's sugar content just like we eat food to maintain our blood sugar level.
The flames of a fire don't actually have to come in direct contact with the wood studs in the walls for those studs to start burning. Spruce and fir have a "kindling temperature" or "kindling point" of about 200 to 300 deg. C at which they will start burning spontaneously even if there is a layer of sheet metal between the fire and the wood. As long as there is air present for the reaction to proceed, all you have to do is heat that wood to between 200 to 300 deg. C and the wood will spontaneously begin reacting with the surrounding oxygen in the air to produce CO2 and H2O. That is, it will start to burn. No flame has to touch that wood for that chemical reaction to start and proceed at an accelerating rate (because it's an exothermic reaction). If there isn't enough air for the wood to burn, you will distill the wood to produce wood alcohol which is highly flamable when oxygen is present.
I think this "Inferno" paint is playing on the common misconception that the flames from a fire actually have to come into contact with the wood studs in the walls of a house for those studs to start burning. And, if you don't mind my saying so, I would believe that the people making and marketing that Inferno paint are fully aware that it's a popular misconception that might make them a lot of money selling "fire proof" paint.
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And, in a fire you easily exceed the kindling temperature of wood, so I don't see how having "Inferno" paint on the walls would prevent the wood in those walls (and therefore the whole house) from getting hot enough to start burning. The only possibility of that being the case might be if the paint prevented air from getting into the walls to react with the wood so that you produced flammable wood alcohol instead (which would probably leak out of the wall and spread the fire).
I'll tell you what WILL DEFINITELY increase the fire resistance of your home, and that is adding another layer of drywall to your walls and ceilings.
You see drywall is made of gypsum, and gypsum is calcium sulfate dihydrate, with the chemical formula CaSO4.2H2O
And it's those H2O molecules in the gypsum that make all the difference in a fire. That's because as you heat gypsum, it chemically breaks down at about 100 deg. Celsius when the gypsum absorbs heat, releasing H2O vapour in the process and leaving behind a fine white powder; calcium sulfate or, CaSO4.
As a result of that chemical transformation that takes place at about 100 deg. C, heat applied by a fire will only drive that reaction, not heat the lumber behind the walls. As long as there is gypsum between the fire and the wall studs, the wall studs themselves will never exceed a temperature of 100 deg. C which is well below the kindling temperature of spruce or fir lumber. The more gypsum you have between the fire and wall studs, the longer the wall studs will remain at a temperature no higher than 100 deg. C, and the longer the house is protected against fire. That is, keeping wood below it's kindling point is an effective way of preventing it from burning.
It's kinda like boiling water on the stove. It doesn't matter how hot the stove surface element is, as long as there's water in the pot, that water won't get any hotter than 100 deg. Celsius. The reason why is because all the heat applied goes into boiling off the water, not raising the water temperature to above 100 deg. C. The hotter the surface element of the stove, the faster the water will boil, but the water still won't get any hotter than 100 deg. C. It's the same with gypsum; the heat applied by the fire results in the gypsum breaking down into CaSO4 and water vapour at about 100 deg. C, so the wood studs behind that drywall won't get any hotter than 100 deg. C until all of the gypsum has been converted into calcium sulfate, CaSO4. The hotter the fire, the faster that gypsum is going to break down into CaSO4 and water vapour, but neither the gypsum nor the studs behind them will get any hotter than 100 deg. Celsius or so as long as there's gypsum available between the wood and the fire to absorb that heat.
Obviously, applying gypsum board on the exterior of your house would protect the exterior of your home from fire as well. Ordinary drywall isn't waterproof, so you'd have to find a product made from gypsum (like Georgia Pacific's "Dens-Shield" panels) that are. In fact, all the major gypsum drywall producers make special drywall panels expressly for fire protection. Fire resistant drywall is drywall with glass fibers in the gypsum core that hold the gypsum together so that it doesn't break off in big hunks during a fire, thereby exposing the wall studs to the heat of the fire.
I think it would also make sense to ensure that your roofing materials aren't flammable because asphalt shingles are typically what catches fire first on a home exposed to sparks or heat from a wild fire.
If you phone your local fire inspector, he will confirm what I'm telling you about the protective effect the gypsum in drywall has against fire. And, ask him if painting a wall with fire proof paint so that the flames of a fire don't actually touch the bare wood studs would prevent those studs from getting hot enough to start burning by themselves.
You forgot to mention INFERNO paint runs about $1000 USD per gallon. This is okay for a small project I guess, but a house? I dont think so. I agree with Mr. Kelebay's analysis of gypsum. It would help protect until all of the water is driven off.
I believe however the effects of water in gypsum board would be short lived. I would ask the question as to how long it takes to drive off all the water in 1/2 inch drywall in a typical 1500 degree F bedroom fire. I dont know the answer to that, a few minutes maybe? Also the heat would find the wood, light fixtures, power sockets and switches will melt away quickly.
If your looking to protect the exterior of your home, might be less expensive to clear 100 foot of brush and grass all around, and install a couple of extra hose bibs? Maybe when your roof expires, replace it with metal or ceramic?
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