How do I block the skylights?

March 13, 2012 11:03 AM

Low-tech DIY internal skylight covers. Help?

We are renters. The house has two domed plexiglass skylights (dining room and living room). We love letting the light in, but during the summer it can get insanely hot in the house. Need ideas for ways to deal, things we can do ourselves for little cost. Aluminum foil, cover-with-a-sheet-thumbtacked-to-the-ceiling, reflective film (not great for domed plexi), some combination of things? It's okay if it actually blocks the light and makes the house a cave if it's something we just put up on hot days. If it's a permanent or semi-permanent installation we'd still want to be able to let light in. We're open to suggestions. Thanks!

posted by thrasher to home & garden (14 answers total)

Are you sure it's the skylights that are heating up the house ? (ie it probably isn't the light coming in that warms things, rather radiant heat or air-leaks in the house or around the skylight itself)
posted by k5.user at 11:08 AM on March 13, 2012

(hit post too soon) if it is air leaks around the skylight, I imagine you could use the same plastic wrap and double-sided tape people use in the winters around windows to keep drafts down.
posted by k5.user at 11:09 AM on March 13, 2012

Putting stuff on the inside won't help nearly as much as putting something over the outside, if you can get up there. Just tying a piece of fabric over them, for example, that lets in just a little light. If all the light is still going through the plexi, your problem becomes reflecting it back out, which is hard to do.
posted by beagle at 11:14 AM on March 13, 2012 [1 favorite]

You can get big styrofoam panels in a variety of thicknesses from the insulation department of your local home improvement store. You should be able to find a 1" thick white styro panel (or two) that you can cut to fit inside the skylight recess. Styro is a great insulator and very lightweight so you can just tape it up. Also it will let a little bit of light through because it's white and not too thick.
posted by seanmpuckett at 11:14 AM on March 13, 2012 [1 favorite]

Beagle is right, but I can't get roof access, so I put 4 small hooks in the ceiling, cut out a piece of fabric, and made 4 small holes in the corner of the fabric. Pretty easy to install and remove. (You could use thumbtacks if you wanted to minimize the size of the holes in the ceiling.) Then you can choose to put some foil on top of the fabric to reduce the amount of light further - for example, when you are out during the day. In fact, I found that I just leave the foil in all the time, as the fabric hangs down a bit and lets in enough light.
posted by Mr.Know-it-some at 11:15 AM on March 13, 2012 [1 favorite]

I could see sticking up either wax paper or parchment paper with that blue tacky stuff around the edges working well to diffuse the light only a bit while still causing the heat to bounce off. See if that works. A bit of trial and error maybe? (But still not bad for a grocery store solution :)
posted by jay.eye.elle.elle. at 11:16 AM on March 13, 2012 [1 favorite]

Nylon or black aluminum screens work pretty well for this in my parents' indoor greenhouse. Depending on the screen density they can reflect some or most of the radiant heat. They attached them by putting a stick with a string tie, like a hammock on both ends of the screens, then hung them on the window frames with suction cup hooks, two on each end to prevent twisting.

A word of caution, however. The heat, reflected back up at the window, can be very hard on the seals. My parents had all of their double-glazed windows lose their seals because of overheating, caused by the reflections from the screens. Every window that had a screen reflector on it popped and lost their insulation, all of those that didn't have screen reflectors were ok. They replaced all of the ceiling panels on the solarium roof as they needed to move the screens around.
posted by bonehead at 11:18 AM on March 13, 2012

No input on the material or inside/outside question, but for the fastening, I'd recommend the velcro strips from Command. They're advertised as picture hanging strips, but what they really are is a mating pair of velcro strips (great for something you want to put up and take down a lot) with the Command adhesive (great for renters).
posted by clerestory at 11:23 AM on March 13, 2012 [1 favorite]

I have a skylight in my place in the living room, and it is a prime source of heat in the summer. I also use a projector as my TV, so that much direct light coming in really sucks when I want to watch something in the daytime. I needed a solution that would block light and ideally also the heat, but still be quick and easy to put in and remove. What I came up with was I built a wooden frame from 1x2s that fit the inside of the skylight with about 1/4" of give and then covered the frame with whitish vinyl (to match the ceiling color). I then covered the sunward side of that with aluminum foil. Then I installed 4 small angle brackets at the base of the skylight "silo" so that I could put one end in, slide it up a bit and pop the other end in on the brackets, and then drop the first end onto the brackets as well. All told it takes about 10 seconds to insert or remove my cover and it does a great job of blocking the light and heat. I'm at work now, but if you want me to take pictures when I get home of what I did and how it works let me know.
posted by barc0001 at 11:25 AM on March 13, 2012 [1 favorite]

Great suggestions everyone.

bonehead, I hadn't thought about the reflected heat causing a problem for the skylight itself, thanks for pointing that out.

barc0001, how long have you used your solution - and have you had the problem of frying your skylight seals?
posted by thrasher at 11:31 AM on March 13, 2012

We had a west-facing window that we blocked with rigid insulation cut to fit the window, and it actually ended up cracking the glass due to the heat buildup. So yeah, be careful how much heat you trap against the skylights. Stopping the heat before it gets into the house is really the best strategy (safest and most effective)
posted by misterbrandt at 11:38 AM on March 13, 2012

I have a window very much like this and have something very similar to this shade that I put over top of the window in the summer. You need to keep the heat on the outside side of the window.
posted by the jam at 11:49 AM on March 13, 2012

Just to give you an idea of what kind of heat you are getting/blocking look up passive solar heaters. I'll be building one for my greenhouse for next year using coke cans and a salvaged window.
posted by srboisvert at 1:30 PM on March 13, 2012

I've been using my cover for close to 3 years and haven't had any issues with it. The aluminum foil doesn't concentrate light because its surface is irregular so it tends to reflect a goodly portion of the thermal energy right back out again. I'm sure there's some greenhouse effect in there and it's probably around 40-50C in there or maybe a bit more on a really warm summer day, but it hasn't caused any problems I can find with the seals.
posted by barc0001 at 3:05 PM on March 13, 2012