Silver roof coating question

[gobygoby]

Hello fellow skoolies,
I was hoping some of you would be able to share your experience or answer some questions about roof coatings.

I am about to paint the exterior of my bus, and I have narrowed down my paint options quite a bit, but I am stuck on making the final choice.

Requirement #1: The entire bus needs to be painted with some sort of solar reflective paint. I don't just want to protect the roof, I want to protect the sides as well. The sides and roof do not necessarily need to be the same type of paint, but it would be nice.

Requirement #2: The sides need to be silver color. I would prefer the top to be silver too, but I would be amenable to a white roof and silver sides if it makes sense.

Requirement #3: It can't cost a fortune. I'm looking for around $70-$100 per 5 gallon bucket.

Requirement #4: There are two metal roof supports running the length of my '98 Thomas bus which, when sealed, will create standing water between them. So the roof coating will need to deal with that.

Requirement #5: The bus needs to remain movable. A coating that hardens and could break under road conditions could work for a shed, but not for the bus.

[gobygoby]

Continued...

Specific questions:

Question A: I have run across silicone roof coatings and elastomeric acrylic roof coatings, is there much of a difference between the two?

Question B: What do you think of fiber filled roof coatings? Some say they dry hard but can also expand and flex with roof expansion. I'm not sure what to believe.

Question C: Is it worth buying two different types of coatings? The roof will have standing water on it, but the sides won't, so maybe I don't need the same material on each. This would mainly become an issue if the top paint and side paint were very different prices, or different colors.

Question D: Is there a big difference performance-wise between silver paints and white paints?

Question E: Will the silver paint remain shiny over time? If not, is there something I could paint over it to protect it?


Thanks in advance for your help, I really appreciate it!

[gobygoby]

Here is a picture of the metal roof supports I was talking about:

[Robin97396]

Someone correct me if I'm wrong because I'm not a paint guy. I also need to paint if it ever stops raining.

I believe most people here are using the white elastomeric coatings for the roof, often with the insulative beads added.

There do seem to be a couple threads with people using silver paint on the sides of their buses.

This is the slow part of the day generally, so you should have multiple choices and accurate references soon as other people weigh in.

If you'd like to search it is often said to use google to reference the subjects on this site you need answers to, as a simpler and more accurate means of searching.

Nice skylight.

[gobygoby]

Thanks Robin97396 for the comments and compliment about the skylight. The previous owner cut a hole next to the emergency exit for a roof top AC unit. I had to remove the AC because I wanted to maximize the interior height (I did a 39" roof raise). I happened to have a piece of plexiglass which was big enough to cover the AC hole, but not large enough to cover the exit. I covered over the exit with sheet metal and enlarged the AC hole to the size of the plexiglass. In that photo, the plastic is not yet installed, but on my blog you can see better photos of the finished product.

[leadsled01]

I have used the silver roof coating from home depot on my old camper. What a mistake, gray streaks running down the side ever since... I don't think that piece of plexi glass is going to be a long term skylight. imo

[slaughridge85]

I used henry's 555 aluminized roof coating on my bus and it went on great. Prep work is the key, and make sure you read the full directions and understand them before you start. It must not rain or get excessively humid for two to three days after application. $77 for 5 gallon pail and I was able to get two good thick coats on and have a little left over. It is designed for old metal roofs and is oil based and will seal minor leaks and hairline cracks. You should be able to paint over it after it fully cures if you use another oil based paint. Scuff sand the top and then give it a good wash and degrease and you wont have any problems. It is gritty looking so if you dont like that then I would pass and find another coating.

[gobygoby]

Originally Posted by slaughridge85

I used henry's 555 aluminized roof coating on my bus and it went on great. Prep work is the key, and make sure you read the full directions and understand them before you start. It must not rain or get excessively humid for two to three days after application. $77 for 5 gallon pail and I was able to get two good thick coats on and have a little left over. It is designed for old metal roofs and is oil based and will seal minor leaks and hairline cracks. You should be able to paint over it after it fully cures if you use another oil based paint. Scuff sand the top and then give it a good wash and degrease and you wont have any problems. It is gritty looking so if you dont like that then I would pass and find another coating.

slaughridge85, thanks for the reply. I did not know the paint turned gritty. That would be fine for the top I guess because no one will ever see it. Do you know of any silver paints that will remain shiny on the sides of a bus?

[Mark_In_MA]

Originally Posted by gobygoby

slaughridge85, thanks for the reply. I did not know the paint turned gritty. That would be fine for the top I guess because no one will ever see it. Do you know of any silver paints that will remain shiny on the sides of a bus?

Standing water on the roof is asking for trouble. You've got to let it drain at some point, or it will find a way inside the bus. You'll also find it collects water while driving - which will then slosh forward every time you tap the brakes. Even a very, very shallow puddle 2x38 feet will hold quite a bit.

Silver paints in general tend to dull a bit over time, because the "tint" in them is often aluminum. Just like all metals, it will dull and develop a little surface oxidization over time.

Don't be fooled by the color that it does a darn thing to reflect heat any more then any other light color will.

The elastomeric coatings a lot of people use on their bus roofs are designed for just that - vehicle and trailer roofs that need to be able to flex and vibrate over time.

[cadillackid]

color DOES matter in heat reflectivity... VERY much so!....
-Christopher

[EastCoastCB]

Flat white is the most reflective. that's why so many indoor pot growers use it.

[slaughridge85]

Originally Posted by EastCoastCB

Flat white is the most reflective. that's why so many indoor pot growers use it.

Yep he's right. I used the aluminized roof paint not just for the little bit of reflectivity but also because it will cork up any pinhole leaks or small cracks in the sheet metal and at the seams. It has succesfully stopped the last of the leaks in my ceiling. Also the stuff I used has aluminum fibers in the paint and thats why it reflects heat so well. Any aluminium colored paint without the fibers will be pretty much useless except for being aluminium colored...