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Store near me has both, I've heard others mention perhaps using the elastometric to help cool the roof, but I saw this other fibered coating at about the same price with about the same claims to help keep the roof cool. The elastometic mentions RV roof use in particular on the label. Anyone know if one or the other is best? Elastometric is water based, and I think the fibered is alchol based... differert chemicals used for similar results? Anyone have experience with the fibered variety? If not, I'll just go with the elastometric if I choose to put some up there. thanks. Roof Coating at Menards®
 

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Any bright white paint suitable for cars will work. TiO2 only for the pigment. This is strictly a reflection issue unless you have other needs.
 

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Any bright white paint suitable for cars will work. TiO2 only for the pigment. This is strictly a reflection issue unless you have other needs.
I have to disagree. I live in an late model Airstream with a white painted roof. The white portion of the trailer gets almost as hot as the bare aluminum part.
I’m actually in the process of prepping my Airstream and (white!) van roof for Henry’s Tropi-Cool. It’s a 100% silicon roof coating with limited lifetime warranty. It’s highly recommended on the Airstream forum and at least one member on this forum coated his gray van roof with it as well.
I’ll report back once I have applied it.
 
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I have used the elastomeric on my house, a metal roofed shed, a shingled roof that was failing, and a low sloped roll roofed carport. I performed well on all and sticks to metal like stink on a skunk! It is rated for cooling. It works.
 

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I have to disagree. I live in an late model Airstream with a white painted roof. The white portion of the trailer gets almost as hot as the bare aluminum part.
I’m actually in the process of prepping my Airstream and (white!) van roof for Henry’s Tropi-Cool. It’s a 100% silicon roof coating with limited lifetime warranty. It’s highly recommended on the Airstream forum and at least one member on this forum coated his gray van roof with it as well.
I’ll report back once I have applied it.
If your Airstream is like most, wouldn’t you expect the shiny bare aluminum to reflect solar heat even better than white? It’s not clear what exactly you are disagreeing with.
 

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I found a few good write-ups on color reflectivity when researching roof paint. White reflects all colors in the spectrum, therefore absorbing/generating the least amount of heat.
Reflective surfaces like SS, aluminum, chrome being the worst, it had something to do with emissivity.
They absorb some part of the light spectrum and though they take longer to heat up than something black, they don't release their heat as quickly an eventually get much hotter. Can't remember the exact wording or find the write-ups.
I'm sure @RDinNHandAZ can testify to the difference between white and chrome in southern AZ.
 

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They make a lot of heat resistant stuff out of silicone. Cooking utensils, oven mitts, etc.
I have to assume silicone doesn't conduct heat very well.
That would lead me to think that a white, silicone paint would be the best product to keep the top of a metal roof cool.
 

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The white silicone (Henry's Tropi-Cool) is much different that just having a white painted roof. Even a white roof will absorb a lot of heat. The silicone coating prevents this heat absorption. I did a blog post and it does an amazing job in my opinion. Here are the results after applying the white silicone roof coating.

"...On an April afternoon at about 1PM in Oklahoma when I tested, the ambient or air temperature was 77 degrees F. The van was parked in full sun. The underneath side of the Tropi-Cool coated roof was 80 degress, only 3 degrees warmer than ambient. The underneath side of the roof with no coating was 137 degrees F! Over 5o degrees hotter than the coated roof metal. ..."

Complete post:
 

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If your Airstream is like most, wouldn’t you expect the shiny bare aluminum to reflect solar heat even better than white? It’s not clear what exactly you are disagreeing with.
What RnR said... what I disagreed with that just plain white paint on a metal surface suffices. The bare aluminum is VERY hot, the factory white anodized (modern) Airstream roof is marginally better but still very hot. White metal roofs with either an elastomeric aka acrylic paint or silicon based paint makes a huge difference. Many Airstreamers tested this with heat meters. Thus I’m covering both my white Airstream roof and my white PM roof with aforementioned Henry’s Tropi-Cool silicone paint. I’m even contemplating painting my inside side walls of the PM with it underneath the Polyiso panels to reduce thermal conductivity since I have it available.
 

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My first thought is that it's very expensive at $50/gal and may not have a good result:cost ratio in that application.
Plus, not much sticks to silicone, so you might have a hard time adhering your insulation.
Just a thought.
 

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The white silicone (Henry's Tropi-Cool) is much different that just having a white painted roof. Even a white roof will absorb a lot of heat. The silicone coating prevents this heat absorption. I did a blog post and it does an amazing job in my opinion. Here are the results after applying the white silicone roof coating.

"...On an April afternoon at about 1PM in Oklahoma when I tested, the ambient or air temperature was 77 degrees F. The van was parked in full sun. The underneath side of the Tropi-Cool coated roof was 80 degress, only 3 degrees warmer than ambient. The underneath side of the roof with no coating was 137 degrees F! Over 5o degrees hotter than the coated roof metal. ..."

Complete post:
How do you feel about my plan of painting the inside side walls with Tropi-Cool before attaching Polyiso? I think I could even finagle getting some of it inside the ribs. What have me the idea is OurKaravan who saw a huge difference in inside temp in his Sprinter after pairing it with Lizard skin on the inside, under his Thinsulate. He lives in Sacaramento, very similar temperatures to the California High Desert I am at the moment.
 

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My first thought is that it's very expensive at $50/gal and may not have a good result:cost ratio in that application.
Plus, not much sticks to silicone, so you might have a hard time adhering your insulation.
Just a thought.
I attached my Polyiso with self adhesive pins on the side walls. I didn’t feel like messing with 3M 90 or or breaching the panels and waiting for Great Stuff to cure. I already have them installed, minus Great Stuff on the edges, so they are easily removed. I have to buy a 5 gal container anyways for my Airstream roof and will have quite a bit leftover. So I thought I might as well.
 

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It is intended to be on the outside and prevent radiant heat from heating the metal. Not sure about the inside. I think trying to glue something to it would be problematic also, but your pins may solve that.
 

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From reading about the products and materials used in the products, I could be wrong.

The titanium oxide reflects the visible spectrum heat.
The silicone insulates. I'm guessing here, but I believe it insulate(absorbs) against infrared heat.
The elastomeric is for substrate movement.

There is a reason why you can get oven mitts made from silicone and not elastomeric.

Used on the inside Tropi-cool's silicone properties should reduce the sheet metal heat transfer, thinking oven mitt here.
 

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The white elastomeric is incredibly effective. I know nothing about the other product. I can walk barefoot on my elastomeric flat roof in AZ at 100º+ in the blazing sun and it feels COOL. if I touch a tool or a piece of metal even shiny stuff like an airstream is with my hand (or bare foot) it would and has blistered. I brought a gallon of the stuff home to NH to coat the roof of my enclosed utility trailer. I know this works. I can measure the results but it may be a few weeks before I get around to the test. This stuff has been used for many years for this purpose. If there was a better product Arizonians would embrace it. They use white elastomeric.
 

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I don't see why a silicone coating on the inside as insulation would do much to reduce heat transfer to the interior compared to just using Polyiso without the silicone.

Insulation materials are rated by R value per inch. For polyiso, its R6 per inch of thickness. For silicone is about R3 per inch, so a thick coating of silicone of 0.1 inch would add R0.3. If you are already using 1 inch Polyiso at R6, it does not seem like adding another R0.3 is worth much?

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Regarding how the Polyiso is bonded to the van skin....

Using GreatStuff is a proven method -- it adheres the Polysio very well, it prevents water vapor from getting behind the Polyiso and condensing on the mental, its been proven durable, I've never heard of anyone using the GreatStuff attachment having a problem with squeaking insulation. I think that with other methods you take some risk that in the long run they will not work out as well.

Gary
 

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@GaryBIS, just talking, none of this maybe cost effective or practical.

Reading a little further they are all elastomeric, some contain silicone or acrylic or solvents. The silicone and solvent solve the water ponding problem that acrylics can't. Maybe an unintended result of the silicone (min 22 mils) the small insulation affect it has.
 

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All I know is that I have the same dark gray van color that @WanderingWakes has and if I remember correctly, the before/after was like 40-50F difference on the bare underside of the ceiling.
Plus it's extra seam leak protection.
That was all I needed to go spend $50 on a gallon of this stuff.
Honestly, to knock that much temp off the roof, it's worth 4x that much.
 

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This is just an opinion, no experience with this stuff.

All this talk about roof coatings temperature reduction got me interested. So naturally I started looking for long term results. I don't like what I see long term(approx 5 yrs), pin hole caused these on a metal roof, actual coating is unknown. The pin hole over time allows water to enter causing an expanding moist void under the coating, I'm not sure what will happen to the factory paint. With my luck this could be my roof. I guess one needs to believe how it adheres to the metal and do proper application. I personally need think on this.
I don't have any info for van roofs.
63580
 
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