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Dear PoPville – Painting Our Roof

by Prince Of Petworth April 26, 2013 at 2:30 pm 37 Comments

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Dear PoPville,

With the hot weather soon returning to DC, I thought the topic of painting one’s roof white/reflective might be an interesting PoPville topic. It was one of the many recommendations we received from a recent energy audit—lots more to do, but the roof-painting is where we chose to start as A) something we could do ourselves, and B) not super-expensive.

Anyone else think about painting your roof white?

  • Michael

    I painted ours white a few years ago and it has cut down our cooling bills significantly. It also helps to offset global warming.

    • anon

      Studies have shown the practice might in fact exacerbate global warming, or at best be net-even. It’s far from settled that this is actually a worthwhile practice on a macro scale.

      • Hello Goodbye

        You’ve got me curious. Why would it exacerbate? Can you link to one of these studies?

        • Anonymous

          Not OP – but I’m guessing it has to do with the energy cost of manufacturing the paint itself.

        • Identified

          I recall a convo with an old work aquaintence, and it went something like the bounceback effect of the rays not being absorbed bounce back up with could then exacerbate greenhouse effect.

          • Anonymous

            That is wrong. Absorbed energy still heats the planet – it’s not like the ground itself is an infinite heat sink – heat it and it heats the atmosphere. It could certainly exacerbate global warming though if any savings via cooling in the summer was more than balanced by increased energy use in the winter, energy used to produce the paint, and any energy used to replace a roof prematurely if it is damaged by the paint or the painting process.

          • Right, it would increase the greenhouse effect, but would still lead to less planetary warming. When black colors absorb the sunlight, that heats up the earth, buildings, brunettes, etc.. When the light bounces back into the atmosphere, some of the light will bounce back (aka the greenhouse effect), but ultimately, less total light will be absorbed by the Earth’s surface, thus leading to less global warming.

        • Anon X

          The stanford study only looks at the physical effects of the absorption vs reflection of the roof surface.

          A properly insulated ceiling, combined with an insulated roof deck, and a reflective membrane on top will lower your energy consumption considerably. The key to get savings in the summer without losing the savings in the winter is the insulation. Without the insulation, in the winter, the reflective effect will actually help cool your house.

          everything the huff post article said was bogus. yes, an improperly installed roof can be problematic. shocking.

          as far as I know, stanford’s study didnt look at hte global warming impact of using less energy to heat and cool buildings.

  • Anonymous

    We did it in the fall. And our energy bills this winter were the highest they’ve ever been– by a lot. See, when you do something that makes your house cooler in summer, it makes it cooler in winter, too. Did not think that through.

    So, when the home-improvement kitty is replenished, we’ll be spending it on improved insulation for the attic– prior to the white roof, the existing insulation seemed to do the trick.

    • Anonymous

      Hmm, maybe throwing a big white tarp over the roof in the summer is the solution!

      • ah

        Or a dark blanket in winter.

    • Anonymous

      This is true, so it does help to think it through. I painted the roof white knowing it might have the opposite effect in winter because I just hate being miserably hot more than I hate being cold.

      • Hello Goodbye

        Plus heat rises. I’ve been thinking about doing this since my top floor gets sooooo hot in the summer. Don’t have the reverse problem in winter.

        • Anonymous

          don’t waste your time. seriously. the impact of doing this on a poorly insulated roof is roughly akin to lighting a candle to heat your house in the winter.

          • If you are the original “Anonymous” in this chain (can’t be sure), then this comment doesn’t make sense — painting your roof white *only* had an impact on your house’s temperature in the winter? Seems that the only two possibilities are that it reflects heat (cooling in summer and winter) or it doesn’t (no impact at all).

            Clearly insulation is a huge factor, no doubt. But having a pitch-black roof boiling in the sun vs. having a reflective, cool-to-the-touch roof would seem to have an impact as well.

          • Anonymous

            I’m the original anonymous, not the “don’t bother” one.

            We just did it last fall, so I can’t yet say if it has an effect on cooling. I’m very anxious to find out.

          • Anonymous

            ordered chaos, i’m the anonymous telling people not to bother. Maybe it will help around the margins, but if your top floor gets really hot and tough to air condition in the summer this will not even make a dent in the problem. seriously. i had the exact same line of thought, wasted money and a day doing this, and found it to have exactly zero effect.

  • MW

    What products have others used to do this? It is a project I’ve wanted to do for years now. Any recommendations on brands?

    • Henry’s Solarflex Roof Coating. Its about 80 bucks for a 5 gallon bucket at home depot. There are one or two other brands out there but this seems to be the best.

    • After some research we chose Henry #687 EnviroWhite Roof Coating. Henry has several varieties of roof paint with varying reflective-life (longer-lasting = more $) and other features. They go into exhaustive comparative detail on their website.

  • jcm

    Is the white a large improvement over the silver stuff used for sealing?

    • I have silver sealant. You get the reflective benefit, PLUS protection against leaks.

  • I would consider it if I weren’t afraid of heights.

  • OP here. We used Henry #687 EnviroWhite Roof Coating. Two five-gallon containers were enough for two coats of our tiny roof. Getting those monstrously heavy paint buckets up onto our roof was pretty painful (literally, for the whole week following) but overall it was pretty straightforward. Thick-pile paint rollers (1 1/4″ IIRC) worked well.

    We need to improve insulation too, and re-caulk lots of edge areas, and re-seal our A/C ducts… ah, the joys of homeownership. But we’ve always had more trouble keeping the house cool on hot days than vice versa, and the warmest room in the house was the master BR. So we’re hoping this paint makes for a more comfortable summer.

  • Fonzy

    We did it on our flat roof because the A/C couldn’t keep the top floor under 85 degrees in the summer. Once it was painted white, we could easily hold 74 degrees up there all season long. We did four coats of white in two days.

  • The City of Hyattsville installed a crazy reflective white roof on their city admin building. I haven’t heard about any energy savings yet but have not been following it closely.

  • KenyonDweller

    Our third floor used to be brutally hot in the summer until we replaced the insulation. We used the blown-in stuff, which made a huge difference. Our roof is silver, not white. I too wonder whether changing from silver to white would make a very big difference.

    • h streeter

      who did you use for your blown in insulation?

      • KenyonDweller

        Can’t remember, but I’ll try to look it up this weekend.

      • am2o

        I used a kit from these people: Carrying it up to my attic was not fun, but it was not difficult to get the places I could reach. (http://www.sprayfoamdirect.com/home-owners/spray-foam-kits)
        Carrying it up to my attic was not fun, but it was not difficult to get the places I could reach. There is a reason the Demonstration is done in a clean light airy place, and not in a cramped Dirty Attic.

  • Anonymous

    in my experience painting your roof white has no impact if you have inadequate insulation, which, if you’re living in a rowhouse in dc, is probably what you have.

  • Thor

    On a related note, has anyone insulated external walls of an old house? What did you do?

  • Anon

    Has there been a thread about good roofers to replace a mansard-type roof? I need to have my old slate roof redone but can’t find many roofers willing to tackle a 1906 mansard?

    • KenyonDweller

      L & M Contracting can do it. Don’t let the name mislead you; they are pretty much a roofing company. They are not cheap, but they do excellent work, and they know DC mansard roofs. (202) 234-3951.

    • crin

      JR Walls. Saw them tear a mansard down, redo the framing, rebuild the dormers, and fabricate a new metal cornice. Dead on perfect match of the original. Slate roof was the easy part.

  • Anonymous

    Who is a good company to apply the silver sealant? (if you’re afraid of heights).

  • Sounds like a green roof is a better solution.

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