Hot Roof Solution for our Promaster RV Van

Our DIY RV build continues on our Dodge Ram 2500 Promaster cargo van. As winter fades, spring has brought some occasional hot days to Oklahoma. The van is still mostly un-insulated. The ceiling has no insulation, and the bare metal roof gets quite hot in the sun.

I decided that a detour in my build plans was worth the delay in order to address the hot roof. Since there was still much work to be done inside the van, and I am having to do the work with it parked outside. Based on feedback over at the Promaster Forum, I had been looking into roof coatings to address the roof heat issue. Our gray paint color tends to get hotter than white, but we had avoided white for other reasons.

After some research and emailing the Henry company about their products on my van’s metal roof, I decided that a good application of the Henry Tropi-Cool 887 white roof coating would be a likely solution. This is a 100% silicone white roof coating designed to reflect heat and UV rays. I wanted to be sure that it was applied well, so I opted for two coats of the product. The Henry Tropi-Cool is available in 0.9 gallon cans, and two cans would be enough with some left over.

Henry Tropi-Cool 887 White 100% Silicone Roof Coating

The Promaster van roof needed to be washed first, and I used the recommended cleaner from the manufacturer (TSP). In order to keep the white coating from being so obvious from the ground, I used painter’s tape and masking paper to mask off the edge of the roof before it starts to curve downward.

Promaster DIY RV roof cleaned and masked.
The Promaster DIY RV roof cleaned and masked.

With the van roof clean and the sides protected, I applied the 887 Tropi-Cool coating. The consistency was like that of very thick paint, and it applied well with a 3/4″ knap roller cover. I used a disposable brush for a few areas, but the roller was able to cover most of the roof quite well.

I opted for a second coat to make sure that the van roof was covered well. The recommendation is to wait until the first coat is dray, but no more than 48 hours, before applying the second coat. In my case, about 3 or 4 hours was enough, and the second coat was applied. I had wrapped the roller in a plastic bag to keep it from drying out, so the same roller cover was used for both coats.

I wanted to be sure that the silicone coating was on top of anything else, since not many materials will adhere well to silicone. We had already installed the vent fan in the roof, and I also installed the brackets for our 3 x 100 watt solar panels. The black tank vent and solar cable entry glands were installed earlier as well. The only item left to be installed on the roof was the air conditioner. An area was masked off and kept clean for this future task. I have about half a can of roof treatment remaining, and this will be more than enough to apply two coats on the roof after the air conditioner hole is cut and the bracket mounted.

Promaster RV van roof after two coats of Henry Tropi-Cool white roof coating.
A nice white roof after two coats of Tropi-Cool.

I was very interested in determining how much difference the Tropi-Cool roof coating made on the heat absorption by the Promaster gray van roof. Since the air conditioner location had not been coated, the ability to make a comparison would be simple.

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.

Uncoated roof at 137 degrees F versus coated roof at 80 degrees!

I am extremely pleased with the performance of the Henry Tropi-Cool roof coating on my RAM Promaster DIY RV van. The drastic reduction in heat absorbed by the metal roof will help to keep the van cooler in the summer. I am also expecting the roof to be quieter during a rain storm with the layer of 100% silicone rubber to reduce external impact noise. The roof coating, along with 2 inches of insulation above my finished ceiling surface should keep our interior cooler in the summer and warmer in the winter.

Products and Tools used in this project:

Promaster RV Van with Tropi-Cool roof coating, solar panels reinstalled.

Happy Trails…

2 thoughts on “Hot Roof Solution for our Promaster RV Van”

    • Yes, I certainly did not expect that kind of difference. Nor did I expect the coating to keep the roof so close to ambient in full sun.

      Reply

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