June 22, 2018
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Fine and funky painted roof can be cool

By Tom Gocze, BDN Staff

After a week of summer weather, many Mainers are struggling with high temperatures on the second floors of their homes.

Heat rises and the second floor of any house is going to be warmer because of that, but being a relatively simple guy, I always am amazed when I am on the second floor of a building in the summertime and the ceiling is not well-insulated. It gets really hot up there!

To make matters worse, most houses have black or other dark-colored roofs.

Any time of year, a dark-colored roof gets pretty warm. If you couple this factor with poor attic insulation, you probably have bought an air conditioner.

You are now thinking, “He’s gonna start preaching insulating the attic, AGAIN.”

Well, no. (You should insulate your attic to at least R-50, but you already knew that being a well-informed Bangor Daily News reader.)

Instead, let’s consider roof color. Actually, let’s think about the roof of a building a little differently in this hot weather. Let us consider that black roof as a solar collector. Anything that is black and is intercepting sunlight is a solar collector.

In this case, your roof is a solar collector that is not doing anything but making life miserable in the summertime for people who have to live on the other side of the roof.

You say that you just installed that brand-new lifetime warranty full jet — let’s cook them from the ceiling down — black asphalt shingle roof.

There is a simple solution that has been around for a while. It is, perhaps, slightly goofy, but it does work. Paint your roof a light color.

You can paint asphalt roofing shingles white. It is that simple.

If you have ever been on a roof, painting a dormer and that paint dripped onto the roof, you know that acrylic latex house paint never comes off asphalt shingles. I suspect it has to do with the rough granular surface and the fact that asphalt shingles do not absorb water. Paint just stays stuck to shingles.

The acrylic component of latex paint also filters the UV band of visible light and protects the shingles from aging.

And the light colors, especially white, reflect sunlight and keep the roof considerably cooler than a dark-colored roof. If heat does not build up as much on a light-colored roof, less heat penetrates into the house.

This is all good stuff.

There is a drawback, though.

If you take close look at asphalt shingles, you will notice that they are usually made of a couple different colors. Even the lightest-colored shingles are usually something like white and light gray. The granules that are on the surface are what are colored. This color variation makes the roof more visually appealing.

When you paint a roof, the color is all the same. If you paint an asphalt roof all white, it can appear somewhat, how shall we say, “funky.”

But it will be cooler in this hot weather.

The results can be pretty dramatic, especially on marginally insulated ceilings. House temperatures can be 10 degrees lower while attic temps can be up to 40 degrees lower.

The roof does not have to be white, A nice pastel could work and might soften the visual impact or funkiness.

The roof can be sprayed, rolled or brushed. I tried this project on a roof that should have been replaced and found that the application of the latex acrylic paint actually has extended the life of the roof. This was on a roof that should have been immediately replaced. This was done five years ago and it is still fine — funky, but fine.

Or you can always get a black roof and insulate the attic properly.

Questions for Tom Gocze should be mailed to The Home Page, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. A library of reference material and a home-project blog are at www.bangordailynews.com/thehomepage.html.

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