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Community and Q&A

Material choice for large exterior insulated widow shutter

alladd | Posted in Green Products and Materials on

I”m planning to build an insulated shutter system for a bank of 4 patio door sized fixed windows.The bank is 84″ high and about 14′ long. If possible I’d like to do it in one long accordian-fold shutter to minimize edge sealing and operating time. Windows are early 90’s low E double pane. The area has an 18″ long overhang about 14″ above the top of the windows, which seems like a good storage area of the open shutter. Could be made with six 15″ long horizontal sections, as thick as 2″. I’m thinking of making them from something like 1″ foam board covered on the outside with 1/8″ or so exterior (marine grade) plywood. I’m wondering if there might be some sort of aluminum or composite insulated siding material I don’t know about that would work for this. Keeping the assembly light seems possibly important, though I will try to figure out a motorized and perhaps automated mechanism for opening and closing, where weight might not be as important. I’ve searched extensively and found little applicable. Thanks!

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  1. GBA Editor
    Martin Holladay | | #1

    You might want to read this blog by Ajahn Sona (also known as Ven Sonata): An Off-Grid Solar Community.

    Ajahn Sona wrote, "The big innovation is our R-25 polyiso-and-birch-plywood insulating shutters for all our windows. The building has 1,350 square feet of argon-filled low-e dual-pane windows. When it became apparent that the building is over-glazed, we permanently installed insulated R-30 exterior shutters over about 500 square feet of glazing, leaving about 850 square feet of windows exposed. These windows have been fitted with hinged R-25 shutters that open inward. Most are hinged at the top, although some are side hinged. [Editor's note: some interior shutters appear to be sliders.]

    "More than any other feature, these gasket-sealed insulating shutters contribute more to heat retention than any wonder machine or triple-glazed German miracle windows, for far less money… 80% less. (I’d be happy to go into detail if requested). During the 12- to 16-hour night, we basically don’t have any heat loss through our windows. In the daytime, with panels open, there is solar gain. It’s a win-win situation! For eight months of the year, we leave the panels open."

    Maybe he'll post a response to your query.

  2. GBA Editor
    Martin Holladay | | #2

    More from Ven Sonata, in the comments section on the same page as his article:

    "Interior closing panels will easily crack dual-pane windows if left shut with direct sunlight...unless they are tempered. Many of ours are tempered 8 foot sliding doors on the east side. They won't crack but you can get gasket melt. Ordinary single-glazed might not crack since it is the difference in temperature between the two panes which seems to cause the inner pane to crack. We have a military-like discipline about opening and closing the interior shutters. We do have closing exterior shutters on the 5x10 kitchen window so that can be closed in the afternoon when the western stream of summer sun might overheat in summer. Of course all west facing windows are in no danger of cracking until the afternoon since no direct sunlight hits them until about 1 pm in summer.

    "Shutters are a venerable tradition that needs renewing. My thought is interior closing shutters are easiest and they are not subject to weather. They can look better than a jet black night window. If they are light color with a little led downlight they can give beautiful light at night where your window openings are. Secondly, to prevent cracking, a very light fabric exterior blind or panel could be rigged to close at the same time as the interior panel. It doesn't need insulation. It just is a direct light blocker. It can be closed from inside with a winder or push button.

    "Exterior shutters are marvelously effective, as I mentioned, much better than triple glazed windows. Ours are R 30 but even R 40 present no major expense or difficulties. After all it is just a door which closes over a window, how easy is that!"

  3. GBA Editor
    Martin Holladay | | #3

    More photos of shutters at Ajahn Sona's community.


  4. Expert Member

    Here is a link to a house in Alaska that used them;

  5. alladd | | #5

    Yes, I have seen both of those, and that they seem happy with the results is encouraging. Research reveals that interior window quilts need to be very fussily sealed at the edges or they create moisture problems, whereas a functional exterior thermal shutter reduces the windows moisture problems.
    I don't have the required storage space for the sliding or hinged solutions referenced above--either indoors or out. I do have a nice protected area beneath the built-in overhang, built for summer shading of the south facing windows. I imagine many homes have a similar need and opportunity.

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