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Mounting vertical glass units in sunspace?

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  • Mounting vertical glass units in sunspace?


    I’m re-doing a sunroom that was originally constructed in the late 1970s. I’ve attached a couple of pictures to give you an idea. We’ve decided to basically stick with the original design as you can see in the one photo: 3 walls (south, north and west) of basic framing with 34”w x 76”h “insulated glass units” that are 5/8” wide made with 1/8” thick tempered glass.

    From what I can tell, the original glass units were just put into place and caulked in (no spacers on the bottom used). We broke a couple during the “removal” process because the caulk had dried so hard, but otherwise most of the windows have held up well over the years…maybe one or two broken due to hail.

    I've replaced all the original framing with pressure-treated 2x6s, creating rough openings approximately 34 ¼ x 76 ¼”. Our plan is to mount the window units like you see in the ‘window detail’ photo; the glass units would go in where I’ve put the yellow line (although we’re going to use cedar for those outer trim pieces, not pine as shown in the photo). Basically the units would be ‘sandwiched’ in between the trim pieces, and caulk would only be applied to where the trim pieces contacted the glass since the guy we bought replacement windows from said that caulk shouldn’t contact the rubber ‘gasket’/seal around the edge of these kind of sealed glass units.

    The main complication is that when I went in to pick up the replacement glass units (to replace the ones broken during removal or had otherwise lost their seal), the window guy said that these types of units need to be mounted on hard rubber “spacers” (see photo) rather than having them rest directly on the wood frame at the bottom, since otherwise you run the risk of having the units compressed and broken if the wood framing expanded/contracted.

    We had not accounted for the use of spacers when we created the rough openings, so if we’re going to use them we’ll need to go in and take off ¼” of so of the “front” (exterior side) of all 24 bottom pieces/sills to create space for them.

    So I guess I have two issues I'd really appreciate any input on:

    1. Generally, what do you think of what we are planning as far as "sandwiching" the glass units in as shown in the photo ('GlassMountingDetail')?

    2. More specifically, are rubber spacers like this necessary for this type of unit/installation?

    Below are links to some photos to give you a better idea of the project.

    Any advice appreciated...Thanks for your time and help!









  • #2
    Your first three pictures are not coming up. I have been planning something similar but still just planning stage.


    • #3
      What you have sounds very close to something I did in the late '70's. Yours seems larger than mine (??) however. As I remember, the contractor on my work used spacers all around as well as other usual framing/sealing details. Things will indeed change dimension for thermal as well as other reasons.

      One thing: I had to modify the Sunspace framing (6" deep) at the bottom of each lite by adding a "tray" of sorts that protected the bottom portion of the wood framing and channeled condensation away from the framing as it ran down the widows. I tried to control interior moisture in the entire dwelling as best as possible, but I got the house was pretty tight and in a 7,000 DD climate, interior dew points were often higher than interior glazing temps. a good portion of the winter, especially when the sun was [U]not[/U] shining - which was about 70-80% of the daylight hours in the winter. As you might guess, the 76" lites were the most obvious offenders.

      Where are you located ?