I think thermal blankets are usually mylar. I’ve no idea what temperature mylar fails at, but I wouldn’t be surprised if it’s lower than that of a full throttle forest fire. I’ve seen video of that shit in action and it’s scary both how fast it moves and how violent the interior is. Hundreds of tons of fuel per acre, all going up at once, it’s like an ongoing explosion as the combusting matter crowds itself for space.
My first guess was that the reflective surface would act as a thermal barrier against ambient temperature. If that’s just the outer layer it may have some actual insulation built-in too. Considering the use-case it’d be reasonable to engineer for an increased tolerance to some hazard whose benefit compounds alongside other precaution and prep.
i.e. the protective material’s melt point only has to be a bit higher than the shielded material’s flash point for the product to be effective as-advertised. It won’t save the cabin if ambient temp hits ignition or combustion temp but the cost:benefit may still make sense.
Searching for “aluminized structure wrap” provides some results which seem to confirm this.
What was the context of your discussion during firefighting training? Accurate to the marketing copy? Less situationally useful than advertised but still better than nothing? Completely worthless?
Less than marketing, much more than nothing. If you do nothing other than the wrap, there’s a chance it’ll work out. If you add in appropriate prep, such as removing the brush (remove anything like pine needles from gutters, remove all leaves, etc) for at least 30’, then make sure everything around for another 75’ is cut low, mow it down. That will really keep the heat down to a safe level for the wrap.
Also smart to keep the home itself in mind. Roofs should be metal, composite, tile, etc but not woof shingle. Gaps should be checked for and sealed so embers dont get in. Chimneys need to be screened, along with any vents (there are FD reviewed vents too, any state with a wildfire issue has recommendations).
Anyway, yeah, they do work, but it pays to be aware of all the ways to protect yourself/your home. It’ll definitely improve the chances that temps will stay in a range they can be dealt with.
Sparks and embers. And whether it’s aluminum, aluminized structure wrapping, insulation, or mylar, it’ll reflect the heat away from the side of the cabin for a lot longer than no covering. Toss in sprinklers, and clearing of bushes and other scrub nearby, and I’d say this cabin stands a far better chance of survival than it does without.
It’s not going to withstand a 24 hour firestorm directly over it, but I’d rather spend $3k trying to save everything than lose it all because I didn’t try.
I think thermal blankets are usually mylar. I’ve no idea what temperature mylar fails at, but I wouldn’t be surprised if it’s lower than that of a full throttle forest fire. I’ve seen video of that shit in action and it’s scary both how fast it moves and how violent the interior is. Hundreds of tons of fuel per acre, all going up at once, it’s like an ongoing explosion as the combusting matter crowds itself for space.
Typically meant for 300F and below. Melts at just a bit below 500F. Forest fires are several times that temp (like 1600F to 2000F).
This isnt mylar though, mentioned elsewhere its called aluminized structure wrap.
Aside from some of the basics I mentioned about it though, I have no direct experience using it. It was discussed in FF training.
My first guess was that the reflective surface would act as a thermal barrier against ambient temperature. If that’s just the outer layer it may have some actual insulation built-in too. Considering the use-case it’d be reasonable to engineer for an increased tolerance to some hazard whose benefit compounds alongside other precaution and prep.
i.e. the protective material’s melt point only has to be a bit higher than the shielded material’s flash point for the product to be effective as-advertised. It won’t save the cabin if ambient temp hits ignition or combustion temp but the cost:benefit may still make sense.
Searching for “aluminized structure wrap” provides some results which seem to confirm this.
What was the context of your discussion during firefighting training? Accurate to the marketing copy? Less situationally useful than advertised but still better than nothing? Completely worthless?
Less than marketing, much more than nothing. If you do nothing other than the wrap, there’s a chance it’ll work out. If you add in appropriate prep, such as removing the brush (remove anything like pine needles from gutters, remove all leaves, etc) for at least 30’, then make sure everything around for another 75’ is cut low, mow it down. That will really keep the heat down to a safe level for the wrap.
Also smart to keep the home itself in mind. Roofs should be metal, composite, tile, etc but not woof shingle. Gaps should be checked for and sealed so embers dont get in. Chimneys need to be screened, along with any vents (there are FD reviewed vents too, any state with a wildfire issue has recommendations).
Anyway, yeah, they do work, but it pays to be aware of all the ways to protect yourself/your home. It’ll definitely improve the chances that temps will stay in a range they can be dealt with.
Which is in and of itself flammable. Truly, a puzzle just what the devil is going on here.
Agreed, I don’t think mylar would cut it either (Sorry, added more to my comment above while you replied I think)
Sparks and embers. And whether it’s aluminum, aluminized structure wrapping, insulation, or mylar, it’ll reflect the heat away from the side of the cabin for a lot longer than no covering. Toss in sprinklers, and clearing of bushes and other scrub nearby, and I’d say this cabin stands a far better chance of survival than it does without.
It’s not going to withstand a 24 hour firestorm directly over it, but I’d rather spend $3k trying to save everything than lose it all because I didn’t try.