Which Paint For Roof

[Maggie01]

I've read so much that I've gotten myself confused. At first I knew I was going with Henry's Tropicool for my roof. Then I read how it went on textured, yellowed, and looked dirty after awhile. I also read where plain Rustoleum white paint was just as good, as long as you applied multiple coats. Then I read about BusKote, Henry's Solar Flex, Blackjack Elastomeric, Snow Roofing's Elastomeric, KoolSeal Elastomeric, and probably a few others.

I also read about the HyTech Thermocell and Insuladd ceramic bead additives.

Now I have no idea which is better. I wanted to do a poll to see which one most people used, but couldn't figure out how to post one on here.

I want my roof as cool as possible. But I don't want it collecting dirt or difficult to clean. I'm not concerned about leaks, as I will be using Eternabond or Dicor lap seal to cover all rivets and seams before painting the roof to take care of any possible leaks.

Can you add the ceramic beads to regular Rustoleum paint and how many coats should you apply to get the most cooling effect? Also if you added the beads to the Rustoleum paint, would it help any to use it on the entire bus (sides, front, and back), and also on the inside of the bus and if you did would the finish be rough? or would one of the elastomeric paints work better? If so which one?

 

[EastCoastCB]

my strategy is- seal the roof properly and paint it with whatever you paint the bus with. NOT house paint.

 

[PNW_Steve]

my strategy is- seal the roof properly and paint it with whatever you paint the bus with. NOT house paint.

I agree with CB.

No silicon. No Henry's or SnowKote and absolutely no house paint. Just auto paint or industrial enamel.

I would suggest that you consider a white roof. It makes a significant difference in heat gain.

 

[bus-bro]

So far going on a year with Tropi-Cool. It's still pristine white, and nothing has stuck to it or grown on it yet. Not everyone wants a silicon rubber roof, but as far as a paint the stuff is amazing. If I ain't dead I'll repost when I get ten years on it.

 

[Maggie01]

I agree with CB.
I would suggest that you consider a white roof. It makes a significant difference in heat gain.

Hey, I live in Texas where we stay in triple digits during summer. All of our buses down here come with white roofs. I don't think I've ever seen one that wasn't white.

How many coats and would the ceramic beads help? Also if the beads were added how much texture would they add? Even though the inside would be covered with insulation, then some kind of wood, would painting the metal skin of the walls and ceiling with white paint and ceramic beads before insulating help keep the bus any cooler?

 

[musigenesis]

Materials like XPS foam, fiberglass batts, rock wool etc. work as insulators because they trap lots of small pockets of air (or blower gases, in the case of the foam). Air and other gases have a very low thermal conductivity (here's a link to this property for a bunch of different materials) which means heat conducts through them very slowly (heat conducts much more quickly through solid materials). The more the material consists of tiny little pockets of air and the less it consists of solid structure, the better an insulator it will be - but it will also be a better insulator the thicker it is, since this also increases how long it takes heat to move through the insulating barrier.

This is pretty much why no paint of any kind is going to provide any significant insulating effect. If a paint layer were filled with enough tiny air pockets to provide low thermal conductivity comparable to commercial insulation, it would be extremely weak as paint. And even if you could somehow have strong paint that was mostly air pockets, the paint layer is so thin that the effect on R-value would be negligible (imagine how much good a slice of XPS foam 1/32" thick would do).

All your paint layer can achieve in terms of lowering your temperature is to reflect as much of the sunlight hitting your bus as possible (and this is actually a huge achievement, since the radiant energy of light can raise the temperature of your bus far above that of the surrounding air). So you mainly just want white paint. Covering your roof completely with mirrors would also do the trick, although your neighbors (parked or driving) would probably not appreciate that very much.

 

[EastCoastCB]

Materials like XPS foam, fiberglass batts, rock wool etc. work as insulators because they trap lots of small pockets of air (or blower gases, in the case of the foam). Air and other gases have a very low thermal conductivity (here's a link to this property for a bunch of different materials) which means heat conducts through them very slowly (heat conducts much more quickly through solid materials). The more the material consists of tiny little pockets of air and the less it consists of solid structure, the better an insulator it will be - but it will also be a better insulator the thicker it is, since this also increases how long it takes heat to move through the insulating barrier.

This is pretty much why no paint of any kind is going to provide any significant insulating effect. If a paint layer were filled with enough tiny air pockets to provide low thermal conductivity comparable to commercial insulation, it would be extremely weak as paint. And even if you could somehow have strong paint that was mostly air pockets, the paint layer is so thin that the effect on R-value would be negligible (imagine how much good a slice of XPS foam 1/32" thick would do).

All your paint layer can achieve in terms of lowering your temperature is to reflect as much of the sunlight hitting your bus as possible (and this is actually a huge achievement, since the radiant energy of light can raise the temperature of your bus far above that of the surrounding air). So you mainly just want white paint. Covering your roof completely with mirrors would also do the trick, although your neighbors (parked or driving) would probably not appreciate that very much.

Wow man. That's extremely well thought out and stated. Should be a sticky somewhere!

 

[Meathead]

You may be more confused after posting than you were before. [emoji50]
But here goes. I applied Henry’s, in sections, last June. While sitting on the roof with a hand on a coated panel and a hand on my factory white roof there was a significant difference. I was impressed enough to have it put on my tin roof at home. It’s kinda dirty now but I’m parked in a dusty parking area. IDK.

I would bet that the coolest part of my roof is under my solar panels. And when I add my roof rack even more of my roof will be in the shade. I hear that insurance companies don’t like sun decks on skoolies but shade beats any paint any sunny day.

This works better than a hot attic.

 

[WIbluebird]

I just did gloss white tractor paint on my roof. Cost around $50 to do the entire roof and works almost as well as the (overpriced) Tropicool/Henry's stuff.

 

[PNW_Steve]

Hey, I live in Texas where we stay in triple digits during summer. All of our buses down here come with white roofs. I don't think I've ever seen one that wasn't white.

How many coats and would the ceramic beads help? Also if the beads were added how much texture would they add? Even though the inside would be covered with insulation, then some kind of wood, would painting the metal skin of the walls and ceiling with white paint and ceramic beads before insulating help keep the bus any cooler?

A member here did a pretty thorough test of various roof coatings. He cut uniform pieces of sheet metal and coated each one with a different coating. Then he set them on a rack out in the sun and took temperature readings from the under side of the metal.

In the end the ceramic beads mixed in white enamel paint performed the best by a tiny margin. A very close second was sawdust mixed with white enamel. Running a very close third was plain white enamel.

The elastomeric coatings did not perform as well as plain white paint.

The top three were close enough that going with just paint was an easy decision for me.

My Bluebird came from Western Oregon and had a yellow roof. The white shows the moss too much :biggrin:

 

[PNW_Steve]

Just a random thought.....

I have seen a handful of MCI's that came from the factory with a "second roof" spaced about about 1-1/2" above the regular roof and open at the edges for airflow. They were built for customers in Arizona and Saudi Arabia.

If I were stuck in that kind of climate I would retrofit something like that. Fortunately my bus has a "D" button to keep me in reasonable climate.

 

[shaymcquaid]

Hi. Me again. Recommending no one use any elastomeric coating. I regret doing it.
Fix your leaks properly and paint whatever color you wish with automotive or tractor paint. Move on to the next project.

 

[EastCoastCB]

Hi. Me again. Recommending no one use any elastomeric coating. I regret doing it.
Fix your leaks properly and paint whatever color you wish with automotive or tractor paint. Move on to the next project.

:Thanx: Takes a real man to admit his mistakes and let others learn from them as well.

 

[JackE]

Hi. Me again. Recommending no one use any elastomeric coating. I regret doing it.
Fix your leaks properly and paint whatever color you wish with automotive or tractor paint. Move on to the next project.

Why do you regret doing it?

 

[JDSquared]

I used the Henry's solar flex. It seemed almost identical to the Tropicool.
People either love or hate the Henry's stuff. I owned a trailer back in the day, it was some 60's model still on wheels but parked permanently in a MH park. It already had a poorly built extension on it that leaked. We put some Henry's on it and it continued to leak. Then I got another Henry's product and actually followed the directions (hey I was 20-something back then), and never had another problem. Til the ex wife stole it from me in the divorce lol (then abandoned it and lost it to the park. I might still be a bit bitter lol).

It's been a month on the bus and nothing is leaking anymore. They make a specific sealant for it. It comes out more like whipped cream cheese than caulking. But I used it over all the rivets and haven't had a problem with anything not sticking to the paint.

 

[Meathead]

Yes, I think Henry’s works best if you don’t think of it as a waterproofer. Seal your roof. I like the dicor. Then do what you want.
It reminds me of the difference between 3M 4200 and 5200. You can read the labels and get confused. They both say about the same thing. A trusted boat dealer once held up the green tube(4200) and said “This is sealant”. Then he held up the red tube(5200) and said “This is glue”. [emoji1305] I finally got it. Ppl still debate which to use, but I go with that.

[emoji3522]

 

[Oscar1]

Yes, I think Henry’s works best if you don’t think of it as a waterproofer. Seal your roof. I like the dicor. Then do what you want.
It reminds me of the difference between 3M 4200 and 5200. You can read the labels and get confused. They both say about the same thing. A trusted boat dealer once held up the green tube(4200) and said “This is sealant”. Then he held up the red tube(5200) and said “This is glue”. [emoji1305] I finally got it. Ppl still debate which to use, but I go with that.

[emoji3522]

That is so true Meathead
I was told by an old boat builder when you use 5200 expect to break the part if you have to remove it.
Cheers

 

[Oscar1]

You may be more confused after posting than you were before. [emoji50]
But here goes. I applied Henry’s, in sections, last June. While sitting on the roof with a hand on a coated panel and a hand on my factory white roof there was a significant difference. I was impressed enough to have it put on my tin roof at home. It’s kinda dirty now but I’m parked in a dusty parking area. IDK.

I would bet that the coolest part of my roof is under my solar panels. And when I add my roof rack even more of my roof will be in the shade. I hear that insurance companies don’t like sun decks on skoolies but shade beats any paint any sunny day.

This works better than a hot attic.
View attachment 45252

Hey there Meathead
Is this a pic of your house? Converted shipping containers?That looks absolutely awesome.

 

[Meathead]

Hey there Meathead
Is this a pic of your house? Converted shipping containers?That looks absolutely awesome.

No. Not mine, but I know the guy. He’s in New Orleans.This is how I got into this skoolie madness.
I studied container building for several years. Frontier airlines had $49 flights to Denver so I went and looked at properties, mostly old mining claims.

Then I found a guy selling his skoolie, in Colorado. He advertised it like this: “ I built my dream home while living in this bus. Now you can too”.

[emoji362][emoji362]Thats what I really want! A mobile container home! I didn’t buy from him tho. Many of the concepts are the same. We are building inside a metal structure 8’ wide.

Peace

 

[AndiW-SKO]

A member here did a pretty thorough test of various roof coatings. ... In the end the ceramic beads mixed in white enamel paint performed the best by a tiny margin. A very close second was sawdust mixed with white enamel. Running a very close third was plain white enamel.

The elastomeric coatings did not perform as well as plain white paint.

... :biggrin:

Any chance you could provide a link or mention brand names?