Q&A / 

Metal Roof Color Temperature

metal roof color temperature

These were the three pieces of metal I had painted. The black tape is an emissivity target to get accurate temperatures.

Metal Roof Color Temperature - Color Matters Big Time

I used my FLIR infrared camera to determine the temperature of three pieces of metal I had painted three different colors.

The experiment was done at the end of May 2020 in central New Hampshire. I took the photos just a few minutes after solar noon. The strips of painted metal had been in direct sunlight for about 30 minutes to heat up. It was a cloudless day.

One of my FREE newsletter subscribers, David Andersen, had provided great information to ensure the temperature readings were accurate. He's a level III thermographer and had been trained on how to take infrared photos. He pointed out that two things are important :

  • the spot where the reading is taken needs to be a 1-inch by 1-inch piece of black tape. This gives true accurate readings between the three samples.
  • the photos need to be taken in the shade so you're not getting a sun reflection temperature.

I had my camera all set up and then used a cookie baking sheet to create temporary shade for a second or two to take each photograph.

metal roof color temperature

I put the strip on a piece of plywood and tilted it to about a 5:12 roof pitch. This creates a realistic setting. The samples and wood were aimed directly south to get the maximum infrared rays from the sun.

metal roof color temperature

The camera sensor is aimed at the black tape on the white painted metal. It's 104.7 F.

metal roof color temperature

The FLIR camera is aimed dead center on the black painted metal. HOT! 152.7 F.

metal roof color temperature

Here's the green painted metal. It's just a little cooler than the black. 147.1 F.

 

SPONSORS / 

8 Responses to Metal Roof Color Temperature

  1. This is great information, Tim. I remember, back in the day, when nearly all roofs were 'white or gray'. Then came the decorators and architects with the black/dark gray/browns and etc. I inspected homes for a number of years and what a difference in the summer when you got in a light colored roof vs a dark! Thanks for the test!

  2. When I was younger (back in the 1960-70's) our house, and lots of others, had white asphalt shingles. But you never see white shingles anymore. Dark shingles are the norm today. And thus hotter roofs no doubt.

  3. Nice demo. Something I did similar to this in science classes some 40 years ago. What also makes a difference is the backing colour. If the black upper metal has a white backing, it's ability to re-radiate down into the house is somewhat diminished.

  4. Can a brown, shingled roof can be painted w/ a white, reflective coating? It’d be washed & broomed to remove loose ‘gravel-like’ pieces, & allowed to dry. Would coating cause problems beneath the shingles? Should I just remove the shingles on the 5:12 pitch roof & paint 3+ coats directly on the plywood?

    • Whether you can paint a shingle is a question for the manufacturer of the shingle.

      As for removing the shingles, the way the plywood is typical laid means there are gaps between the plywood (they may to small for you to notice, but water can find them). Are you willing to have the leaks in exchange for a cooler roof?

    • Yes, you can paint the brown shingles white. The paint will not cause problems with the shingles.

      NO, do not apply a coating directly to the wood roof sheathing expecting the magic coating to be your roof!

  5. I live in Australia, most of Australia has very hot summers. ....... And yet black roofs are popular. This has always seemed to me to be the definition of insanity!!!!!! You only have to run water through a black poly pipe laid out in the hot summer sun to see how black surfaces absorb heat!!!! You can actually scold yourself if you try to wash your hands in it!!!! Way too hot!!! That is how solar water heaters work.

    If you live in a hot climate, why would you turn your whole roof into a heater???? Yet many people do!!!!

    One other thing..... If you install solar panels on your roof, even though they are black, they actually shade the roof surface below, which has a significant cooling effect on the house. .... A win win situation.

    Black roofs are also a major contributor to the urban heat island effect.

Leave a Reply

You have to agree to the comment policy.