GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Sourcing Triple-Glazed Insulated Glass Units

jonny_h | Posted in Green Products and Materials on

I know there’s a lot of threads on sources for triple pane *windows*, but what I’m looking for are just the insulated glass units.  We’ve got a large window (~11’10” x 6’4″, divided into 12 panes) that’s basically a site-built wood frame (1950s).  It’s the only window I haven’t replaced in the house, but the wood is degrading and it’s all lead paint so the plan is to build up a replacement.  We’ve strengthened around the window, so it’s not very structural at this point, but we like the aesthetic of it so we basically want to build a new frame and install some IGUs that match the performance of what we’ve done in the rest of the house (if not better, given the large glass area.)  I’m looking at a site-built wood frame and a hardware & seal system from Stabalux ( that supports up to 2.5″ thick IGUs, but I obviously can’t fully spec / quote that system until I know thickness , weight, and required sightline coverage of the IGU — but I’m having trouble finding a source for triple-pane IGUs.

– Cardinal, the “big boys”, appears to only sell to window manufacturers
– After a month of back and forth with Alpen, I was just told that they only sell to “certified glaziers”.
– When I search for “glaziers” in my area (around Cleveland, OH), I get either auto-glass replacement companies or standard residential window replacement companies (ie Pella, Universal Windows Direct, Bob’s Budget Vinyl Windows (the last one I might have made up 😉 ))
– I do have a call scheduled with Litezone on Monday, we’ll see how that goes.  However, them (and Alpen for that matter) are both using suspended film technology, which has less of a proven track record than regular glass. Litezone also doesn’t do argon fill (and touts it as a benefit that performance won’t degrade over time because there’s no argon to leak out — fair, but isn’t that just another way of saying you aren’t good at making reliable seals?)

So, does anyone have an idea on where to source quality triple-pane IGUs?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Akos | | #1

    I bought these through my window supplier. You might have to do some legwork and talk to a human in person. You'll probably have better luck with a small or mid size place.

    One option is to order some budget fixed windows with the glass size you want.

    1. jonny_h | | #18

      >One option is to order some budget fixed windows with the glass size you want.
      Funny, I actually thought of that, but ordering a whole window just to harvest the glass and throw away the frame doesn't seem very green ;) (as if a substantial remodeling project is! ha)

  2. user-723121 | | #2

    This is an area where there may be some opportunity, sash and glazing replacement. As windows become obsolete there is no one to repair or replace. I used to get clad replacement sashes from a popular window manufacturer for about $300. The window design has changed and the replacement sash in now $900. Sometimes the glazing is fine but some of the interior wood inside of the cladding especially near the bottom is no longer sound. Would like to know if anyone has successfully replaced all or part of the interior wood for a clad window. The thermopane glass would be reused.


    1. Expert Member
      DCcontrarian | | #3

      I'm actually doing that right now, I have some clad windows where a few of the sashes have rotted out at the bottom. I remove the glass, then carefully take the vinyl cladding off the wood -- it's held on with glue and staples. I've been duplicating the sash profile in my workshop and making replacement sashes and then reassembling everything. The sash profile is complicated but it's all straight cuts and I've been able to duplicate it with a router and table saw.

      Right now the holdup is I want to make the sashes out of 8/4 Spanish cedar, and I haven't been able to find any locally.

      1. user-723121 | | #7

        Thanks, DC

        Any estimate of the time per repaired sash? The $900 quote I got for a replacement sash was a bit of a shock.


        1. Expert Member
          DCcontrarian | | #12

          I'm doing them one at a time so it's slow, I can't have all of the windows out of the house at once. It would be a lot faster if I could do them all at once.

          I spent about a day in the shop getting the profile down, now I can cut a set of rails and stiles in about an hour. Then I need to clean up the old glass and cladding, polyurethane the new sash, glue and staple the cladding, set the glass, install the hardware and install the sash.

  3. kyle_r | | #4

    You could try reaching out to Fiber Frame, a small/medium sized fiberglass window manufacturer in Toledo. They may be willing to order the IGU from Cardinal for you. I would reach out to Tom Mehrman.

  4. Expert Member
    Michael Maines | | #5

    Do you have any traditional glaziers around, the type of company that installs storefront glass, frameless shower doors and repair storm windows? We have a few here in Maine. I have bought double-glazed IGUs from them in the past and they could also get triple-glazed IGUs.

    Edit to add: there are many businesses to choose from in your area:,lf_ui:2&tbm=lcl&q=cleveland+ohio+glazier

    1. jonny_h | | #21

      Thanks, I'll search around a bit more -- for whatever reason when I first searched for glaziers all I was getting was auto-glass companies.

  5. jberks | | #6

    Try searching for shower glass installers or shops. They usually get their glass from the place as the window manufacturers. You can also try finding a glaziers supplier, and ask them if they know any shops that do this.

    For instance, I have a local glass guy near me that I have a working relationship with. I drop off/email a drawing of what I need, he orders it along with all the other glass he needs that week, and I pick it up when it arrives.


  6. tdbaugha | | #8

    Garibaldi is the best from what I’ve researched. They can do very very large triple IGU’s, low iron glass, etc. They’re in Vancouver.

    1. [email protected] | | #10

      I am curious by what criteria are they the "best"?

      1. tdbaugha | | #13

        Large sizes, all the way up to 150 sqft or something crazy. Low iron glass options. Warm edge spacer options.

        Reynaers salesman started his career working for a competitor and he said garibaldi is the best IGU mfg he knows of. Extremely clean and apparently the way they seal the units is top notch.

        1. [email protected] | | #15

          While I would thoroughly enjoy a friendly debate on the differences and advantages between Garibaldi and Cardinal, I don't want to steal the thread over what is a really a side topic.

          If you would enjoy a deeper discussion I am all for it, but it the meanwhile I will leave a couple videos that you might find interesting.

          1. tdbaugha | | #16

            I have nothing against cardinals quality. It’s what’s in my current house. But they don’t offer large sizes in triple pane, which is pretty much standard in my market for a new construction. Trying to convince home owners that upgrading to triple pane is good for comfort, condensation resistance, and energy consumption is hard enough. If you also tell them that they need to downsize 1/2 their windows to use triple pane it’s a non starter.

            I would like to have a discussion about failure rates. I sell real estate for a living. Literally every house 10+ years old has failures and by the time they’re 30 years old, almost every IGU has lost its seal and fogged up. My current house is 30 years old and had Al clad wood weathershield windows. All had failed. Sold a house last year of the same vintage that had eagle windows. Same story. So my question is, how can they make that claim of such a low failure rate? All mfg fail, not just cardinal. But it seems WAY higher to me than the 8.4% failure rate as an industry standard that’s posted on cardinal website.

  7. user-619171 | | #9

    I was also looking for triple pane IGU's and I stumbled on Panes in Canada. I haven't purchased from them so I can't speak to the quality but they ship to the USA.

    1. jonny_h | | #20

      As someone who hates making phone calls, this is interesting -- thanks for the link!

  8. xbcornwellco | | #11

    Alpen High Performance Products is what you need. Just google Alpen HPP.

    Triple AND Quad pane..

    ThinGlass and Suspended Films = 6x lighter in weight than true triples.

    American Made. Innovative since the 1980s. High reputation among Passive House builders and folks.

    One of the rare window manfs to make windows/doors AND do IGUs in-house.

    FYI, they did the glazing for the Empire State Building, and are unbelievably afford for the high performance.

    1. mech644 | | #14

      The OP stated that he was not interested in an IGU with suspended films. What makes you think he needs something he doesn’t want?

    2. jonny_h | | #19

      I'm not completely against suspended films, but I do see them as a somewhat less proven technology than simply glass. For me, the benefit when compared to triple-pane glass would need to be cost -- the weight doesn't matter in my fixed-frame application (also, "6x lighter by dropping from 3 panes to 2? Something doesn't math out there....)

      Regardless, I had actually been giving serious consideration to Alpen -- but after a few attempts to get in touch with them, I was just told that they only sell to "certified glaziers". I'm waiting to see if they'll suggest anyone local & approved who I can try to get pricing through.

      1. cmaierhofer | | #32

        Hello! I know I'm late to the party on this but wanted to at least comment: Yes, Alpen manufactured triples (and quads) for many years using only suspended coated film. However, since they launched "ThinTriple" and "ThinQuad" insulated glass units three years ago, those units have become more than 90% of what they manufacture. Through collaboration with the Department of Energy, Alpen's thin glass units employ a 1.3mm center pane (or panes) of glass in the IGU vs. film. If you haven't already handled that pesky window, please reach back out to [email protected] and we'll help you get this resolved with a high performance IGU!

  9. gusfhb | | #17

    Years ago I bought directly from Cardinal
    I have a commercial address, loading dock and Fed tax number
    I bought ~150 sq ft
    It came via a very particular carrier that apparently only handles glass
    I knew what I wanted and specified it, they did not at that time make triple pane as thick as I wanted so that was really the only area of conversation.
    There was no 'gee what do you think is best'
    Order placement, not consultation
    I emailed some years later[5-6 years ago] and that person had retired and they sent me lists of window manufacturers who had no idea what I was talking about

    I think, if you get the right salesperson, are buying enough that it will make them money, have a business you can buy through, and act like you know what you are talking about, it is possible.

  10. [email protected] | | #22

    reply to tdbaugha, #16 since apparently the site limits the number of replies to replies.....

    Cardinal is big, really big. If Cardinal was a window company they would be arguably the largest window company in North America. Cardinal is arguably the largest residential IG manufacturer in the world (excepting China since no one really knows what's real or not when dealing with Chinese manufacturing statistics).

    Cardinal manufactures about 1/3 of all residential IG units used in North America. The remaining 2/3's of IG units are primarily manufactured by the window companies themselves (most common) or else by using 3rd party IG manufacturers such as Garibaldi and others.

    Cardinal produces about 25,000,000 IG units a year, with over 500,000,000 IG units currently under warranty and another hundred million (plus) that are still around over the 20 year warranty period.

    If Cardinal had an 8% failure rate they would be out of business. Actually they have a documented failure rate of .2% at 20 years (official), but also no more than .2% at 30 years since they introduction of the stainless XL in 1993. Accelerated testing combined with known field performance suggests a failure rate probability of .5% at 50 years. The 8% was never an industry standard in "that's the number to strive for", rather is was a documented average of field failures over a certain time period. Also that number goes back a very long time. Current failure rates are much lower due to improved products and manufacturing techniques, with the provision that there are still bad companies making bad products.

    As an IG manufacturer, Cardinal designs and builds their own IG processing equipment and owns the patents on their spacer technology and IG process. No other IG manufacturer or glass company in North America can say that.

    As a glass manufacturer, Cardinal has 7 float plants in USA, Guardian has 6 (over 25 worldwide), and Vitro has 4* (one is in Mexico), then a few others with one or two floats in North America.

    At its core, Cardinal is a residential IG manufacturer while Guardian, ,Vitro, Pilkington, AFG, are primarily float glass suppliers. The difference is subtle, but real. Cardinal makes their own glass in order to feed their other companies (divisions) ultimately in support the IG operations, while all of the other float glass manufacturers are in the business of selling their raw float glass with any value added (coatings, tempering, laminating, IG) existing to help sell more float glass since that is their core business.

    1. tdbaugha | | #27

      Maybe it’s my climate, bad install, or just dumb luck but there is no way the failure rate is that low. Like I said, I go look at houses for a living, hire inspectors weekly, etc. Not exaggerating, 70% of houses 10yrs or older has multiple failed gas seals. I’m sure their accelerated testing gets to that failure rate but it’s not reality. Kinda like other industries where “we perform extensive durability testing in the lab” and then it hits consumers and fails. When I sell a house and it has failed gas seals, we call a local glass company. They don’t inquire about who made the glass or if there is a warranty. They just replace it. There is obviously no feedback to IGU mfg letting them know that their product failed.

      I didn’t know cardinal could make such large triple IGUs. Why does no window mfg offer large triples? All of the mfg that I looked into that use cardinal top out around 30 sqft max size. Must be their frame limitations? Regardless, glad to hear they can make them and use low iron glass. Hopefully the us window mfg start offering products that use these sizes and materials.

      In addition, hopefully cardinal makes an effort to put this info out there. I have a bid for Reynaers windows which come without glass. My local dealer told me they don’t know of a single mfg that can build triples large enough for my frames. I found garibaldi through calling Reynaers directly. How does a fairly well known glass company that sells 10’s of millions of $ worth of windows each year not know that the biggest glass mfg in the US makes large triple lane IGU’s????

      1. [email protected] | | #28

        Twice yesterday I tried to reply and twice the site told me that I had to be logged into an account to reply, so both times my reply disappeared despite the fact that I was logged in.
        More than frustrating.....but trying again this morning after logging out and logging back into the site.

        Cardinal introduced the XL edge IG system in 1993, prior to that they were using an aluminum box spacer. XL edge is a double sealed stainless steel spacer (the shape of the spacer is patented) that is much better for performance and longevity than is any aluminum design. At the time Cardinal predicted a field failure rate of .25% based on both prototype field testing and lab accelerated testing (and other testing as well). Since the introduction of the XL Cardinal has tracked actual field performance resulting in 30 years of accumulated data from literally millions of actual installs. Based on actual field performance data, Cardinal has determined that the actual 20 year field performance of the XL is .2% field failure, .05% better than predicted.

        Initial failure of an IG system within the first few years of being installed is often (usually) the result of a manufacturing defect (employee error more often than not). In the past 30 years Cardinal has increased use of automated equipment that limits human interaction with the components of the system during the most critical part of the assembly process. Unlike any other IG manufacturer in North America, Cardinal designs and manufactures their own IG assembly equipment. They also hold patent on all component parts of the IG system as well.

        Prior to the introduction of the XL, and for some years after for some customers and as the XL was being phased in, Cardinal used an aluminum box spacer.

        If you are looking at windows that were built prior to 1993, and even for a few years later, if built by Cardinal then they likely have an aluminum spacer and failures using that system at 30+ years is not a big surprise. Like almost every other product on the market in 1993, technology was what it was at the time and it's not the same as today's tech.

        At the same time there were also other "warm edge" spacers such as Swiggle and Intercept, that had a life expectancy that wouldn't take them to 20 years much less 30 with any degree of confidence. Intercept is still around and used by many window companies that manufacture their own IG units, and some independent IG manufacturers as well. Swiggle was replaced by Duraseal (something of a rebranding of an improved version of the same product), which was then followed up with Duralite, which is the warmest edge of all readily available spacers commonly in use in North America. Personally I don't like the look of the product in an IG nor the prospects for long term reliability. While Intercept now has a stainless steel version that is much better than the original tin plated steel.

        I do get the impression from your post that you are saying that the failed units that you see in the homes you sell are from Cardinal, so therefore the .2% can't be accurate, but you also mention that when you replace windows you don't know or care who made it originally. Am I misunderstanding or missing something? How do you know that the windows you are seeing and/or replacing have Cardinal IG system in them?

        As mentioned, today Cardinal produces about 1/3 is all IG's used in North America, but 30 years ago, 20 years ago, that wasn't the case. At the time Cardinal was a smaller percentage of the overall market. Most window companies made their own IG units at the time, even several of the big wood window guys. Since you mentioned them earlier, WeatherShield as an example made pretty much all of their own IG's until relatively recently.

      2. [email protected] | | #29

        "I didn’t know cardinal could make such large triple IGUs. Why does no window mfg offer large triples?"

        I am sure that some do, but it's such a tiny segment of the market that I suspect some don't because they don't see much potential profit in that product and not worth R&D and certification costs to enter that market. Just a guess.....

        "All of the mfg that I looked into that use cardinal top out around 30 sqft max size. Must be their frame limitations?"

        Yep, that and the cost of larger equipment to build, handle, ship, plus testing and certifications, all has to be accounted for.

        "How does a fairly well known glass company that sells 10’s of millions of $ worth of windows each year not know that the biggest glass mfg in the US makes large triple lane IGU’s????"

        Because unlike Garibaldi's (and other similar companies), Cardinal doesn't generally "bid" on commercial projects. Cardinal has a fixed (and growing) list of window companies that they supply with IG units, or glass. The odd job here and there is not part of their business model and while they will certainly try to accomodate window companies that aren't part of their regular business, sometimes there simply isn't capacity to do so.

        Cardinal doesn't advertise to the world-at-large because they don't need to, that's not what they do....

        However they are letting people know that they are offering low iron now, if only shower doors and such at the moment, on the updated website....that's a huge shift in focus and no telling what else might happen.

        1. tdbaugha | | #30

          No I was not insinuating that that the failures I see are cardinal or any other brand for that matter. I was saying their quoted industry standard of 8.4% (or whatever it is) is low. At least in my climate/market. My sample size is small but after touring/selling a couple thousand or so houses, it’s a statistically significant sample.

          It is a shame that the big US mfg don’t put $ into their frames. Heck, andersens top of the line E series is just Eagle windows from decades ago. Like I said before, any custom home built in my area has large amounts of glass and in order to get triple pane units that are medium to large size, you need to go with small, relatively unknown mfg or import windows from Europe. It’s very frustrating from a consumer standpoint.

          1. [email protected] | | #31

            Okay, understand what you are saying. I don't believe that the 8.4% was meant as a standard or goal to achieve, rather I think that it's more like a weighted average about failure at a given timeframe.

            There are systems that are virtually 100% failure over 20 years or even sooner that would definitely impact that number, but when you consider that other systems, again like cardinal's, have order of magnitude better performance numbers, and are a significant part of the entire industry, they can influence the perceived average to looking better than it really is.

            None of which really matters if it's your windows that have failed.

  11. [email protected] | | #23

    Continuing....The largest triple Cardinal makes is 142x94 or 12'x8' or 96sqft. This is smaller than what's available from Garibaldi, Viracon, Agnora, others, but unlike Cardinal the others mentioned are primarily commercial or architectural suppliers, with a smattering of large residential thrown in on the side.

    Cardinal doesn't make the super giant glass units because it would be a miniscule percentage of their overall business model where the gain would not match the investment in time and resources to make it worthwhile to pursue. Could that change in the future? Sure, that's up to the long term planners at Cardinal to decide.

    In the meantime, those projects are bread and butter to companies like Garibaldi and a few others. They specialize in the super large sizes and their success in that area is good for everyone involved.

    Cardinal recently acquired 2 of 3 float plants (3 float lines in the two plants as well as other assets). One of those 3 float lines was set up for AFG's low iron glass production so now Cardinal does offer a low iron glass that they are calling PureVision.

    Curiously they appear to be marketing it toward interior applications such as shower doors and such which is a huge departure from the residential window market that is still their core business......

    Forgot to mention it earlier, 30 years ago both WeatherShield and Eagle manufactured their own IG units. Honestly I think it's a win that they made it 30 years considering the nature of the beast 30 years ago.

    Also forgot to mention concerning Alpen. I think that they make a great product. Curiously, Cardinal owned the original patent on coated suspended film in window applications, but for whatever reason they sold(?) the patent to Southwall Technologies a long time ago. Southwall introduced Heat Mirror to the world and Alpen has always been the best manufacturer of that product going forward. And as an aside, the glass and glass coatings used in Alpen IGU's comes from Cardinal....go figure.

  12. Josh_Dillingham | | #24

    I bought my triple pane windows from Seemray out of Cleveland. Because you're in the area it might be worth giving them a call to see if they sell just the glass. They manufacture some of their windows in Cleveland and some in Germany.

  13. kbentley57 | | #25

    " fair, but isn’t that just another way of saying you aren’t good at making reliable seals?"

    All seals will fail at some point or another. I've read that litezone uses a long line of descants to keep the moisture at bay.

  14. gusfhb | | #26

    I have various windows in my house and while I had one operable window crack I have had zero failures in this house
    14 years
    Replaced the original sliders ca 1970, in 2011-12 I think one had failed.
    some windows we have installed, some are unknown source from I guess the 90's
    Family house circa 1975 has had a few windows fail from new but it is a glassy contemporary [800+sq ft] no more than 10 percent in my estimation over 48 years from new., although all 6 8 foot sliders have been replaced but not primarily because of IGU failure
    My last house had 7 4x6 sliding windows from 1990, sold in 2009 with no failures
    The addition I put on had primarily Andersens, 2001-2009 no IGU failures

    I cannot see quality IGU failure as an issue

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |