• As I started to write this blog, I noticed the date it’s to be published: 9/11. As a kid, I never understood how Pearl Harbor could move my parents’ and my grandparents’ generations into fighting a war. After 9/11, who could ever question that motivation again? I hope we’ll always remember the price paid that day, and many days since, for our freedoms. God bless the good, great, the fortunate U.S. of A. I’m grateful to live in this good land.

    Okay, back to glass. At one time, anyone who had been in the glazing biz for very long had either worked for Cupples or PPG. Those two companies were responsible for everything from the monster towers of the 1970s in Hong Kong to the Twin Towers in New York to John Hancock and Sears Towers in Chicago. At that time, they were the equivalent to what Harmon, Enclos and Permasteelisa have become today. On the glass side, LOF and PPG were what Cardinal, Guardian and Viracon are now.

    It was with some sorrow I read an article about PPG getting out of the glass business. The story pointed out how much higher the overhead and initial investment is in making raw glass, as opposed to PPG’s chemical and coating product groups, where they will now focus their efforts.

    We all used to want to grow up to be PPG. In our eyes, PPG had the best of several worlds: they had a contract division that probably got a huge price break on glass, and they had an aluminum extrusion business.

    This history was brought into focus this summer reading an article in the June 2014 issue of USGlass about PPG Place’s 30th anniversary. The curtainwall system in that building was pretty interesting, as seen in this mosaic display of the corners and typical verticals (hanging in CDC’s Dallas headquarters).

    Photo courtesy of Charles Clift, Curtain Wall Design and Consulting.

    The PPG Place curtainwall was straightforward, and anyone who worked on it back then could probably pick it back up again tomorrow. It had many benefits:

    1. The basic frame members weren’t finished – so the shop and field could be a little sloppy in the handling of the basic frame components;
    2. The interior covers provided thermal separation from the exterior metals, and only these covers were finished;
    3. It was erected and glazed from the floor, minimizing the need for stage time; and
    4. Reglazing vision lites could be done from the interior.

    Bob Johnston, CDC founder, developed the PPG system “from his standard stick wall with collaboration from Gary McKissick, Bob Wheeler and Lloyd Stokes of PPG,” according to Charles Clift, senior principal at CDC (who was engineer of record for the curtainwall). He also recalls that “Phillip Johnson, the architect, required stiffness criteria that were twice as strict as normal industry standards of L/350 and max 3/8″ deflection” and that there was a need for an “unsymmetrical bending analyses on mullion shapes at corner conditions as wind load vectors did not align with extrusion principle axes.”

    PPG will be missed, if they do get out of the glass business or greatly reduce their role.

    As Bill Swango used to say, “be careful of whom you’re envious.”

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  • Flying back from Dallas last week, it was fun seeing the green of spring in the landscape slowly creeping north. Over the weekend here in K.C., it was in the 80s. The trees are budding and leafing, a lot of the flowering trees are in full bloom, and the daffodils are in full flower. Then, this morning, it’s snowing. Go figure!

    I always love to see what might be coming down the pike in architecture, to see what’s about to cross over into the “can it really be constructed?” world. Along those lines, here are some technically challenging curtainwall projects for your consideration.

    Evolvo Magazine 2014 Skyscraper Competition winners. Those might be a little pie in the sky, but that’s never stopped an architect from trying, right?

    There’s a project in Vienna that looks more complicated than it probably is, but the variety certainly livened things up in the detailing and fabrication.

    And, there’s a residential tower going up in NYC that seems incredibly thin: 84 stories tall, not very wide. The main structure is concrete, so the floor plates and columns have to be incredibly thick to resist the sway and twist that comes from so narrow a structure. The top floor condo goes for a cool $79,500,000 (zeroes shown for effect).

    As the economy comes back, we’re seeing more of these pushing-the-envelope-type curtainwalls. Recently, we completed a budget estimate for a curtainwall that was laid out in a segmented plan, with the verticals segmented, as well. It’s sort of a barrel skylight, flattened out somewhat, but then turned vertically on the outside of the building. The bow in the vertical section over a 47’-0” height was about 36 inches. All the glass is flat, there were no curved framing or glazing infills. So that brought it back down to Earth a bit. It’s dramatic, and there are a lot of challenges and opportunities in executing that wall.

    Can it be done? Yes. Technically, it’s not that far out of the box. How about cost? The question, as always, comes down to whether or not the owner wants to pay for it. We’ll soon find out.

    No problems, just challenges and opportunities. Most days, that’s what makes the world go ‘round, isn’t it?


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  • Did you watch the Academy Awards this week?  I didn’t see a lot of the movies (none probably, if the truth be told), but I did come across this list of “America’s Five Happiest Industries,” one of which is closely tied to the Oscars:

    5.  Motion picture and video industries;

    4.  Management of companies and enterprises;

    3.  Educational services;

    2.  Radio and TV broadcasting; and

    1.  Software publishers.

    Funny, nothing associated with glass and glazing made it.  Good for a laugh, right?

    Just in case you thought, like Rodney Dangerfield, that we in the glazing industry “don’t get no respect,” especially when it comes to codes, consider this article, “The Fuzz Factor in Engineering.” It points out the explosion in code requirements for steel:

    1. AISI (steel cold-form steel) went from 22 pages in 1960 to 150 pages in 2012;
    2. AISC (steel construction) “ballooned” from 19 pages in 1941 to 239 pages in 2010; and
    3. Seismic requirements didn’t exist in the steel manual until 1992, at which time they were at 59 pages, and now only 20 years later they’re at 335 pages.

    And, in case you think those codes aren’t directly related to curtainwall and windows, you might want to reconsider that.  The latter two codes above set steel erection tolerances and how much a building can move during earthquakes. This must be accounted for in anchor design, for example.

    There’s also ASCE-7, which drives wind load criteria. That took up 92 pages in the 1988 edition, while the 2010 version is a whopping 368 pages.  Not all of that is related to walls, as ASCE covers roofs, too, but it shows the degree to which codes are changing.

    Granted, IBC has simplified the overall building code picture from where it was 40 years ago.  Who remembers using the UBC, the BOCA and the SBC, and keeping track of the local variations of all of them?  The picture might be simpler in that respect, but the IBC energy code, all the USGBC LEED developments, NFRC certification, etc., have kept the pressure on our industry to be watchful and responsive.

    A crucial point the “Fuzz Factor” article makes is that with codes changing and becoming more detailed, the chance for human error creeping into construction increases.  And as mentioned in a previous blog , there’s some value in peer review, which is something the “Fuzz Factor” PE author promotes.

    I think we already have enough safeguards within the glazing business, in that we have in-house or third-party engineers prepare our calculations, and those are submitted and reviewed by either the curtainwall or glazing consultant, and especially by the project structural engineers.

    I hope the peer review process that the “Fuzz Factor” writer espouses won’t become something we have to include in our calculation preparation or review process.  But who knows?

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