• Robots build your car and computer, and now they’re laying out interior walls. What are the implications for other building components, including curtainwalls? Read on, or be assimilated …

    We’ve all seen interior partition subs marking floors with chalk lines for metal stud and gypsum walls.  The 4/22/13 issue of ENR had an article about a robot used to lay these out to an accuracy of +/- 1/8”.  The CAD or BIM information is entered into the “laybot” robot, which then moves around the floor at 1.8 – 2.2 feet/minute, even around corners, laying out curved or straight walls.  I wonder if it can be adapted for layout of curtainwall? Some challenges come to mind.

    In any curtainwall job, one of the first tasks the field crews undertake is layout of the wall in relation to the structure.  On taller buildings, the forming of the upper floors is proceeding above, while the curtainwall layout, starting on the first floor, has to predict where the building is going to be long before it’s completed.

    The biggest challenge is that a continuous, full-height curtainwall is not on the slab, it’s off the slab, hanging out in thin air.  So, putting a layout line where the wall will be is not feasible (after all this isn’t drywall we’re talking about) except maybe at the base of the wall.   But curbs and overhanging walls can complicate that.  Additionally, perimeter columns get in the way of putting the layout lines right at the edge of the floor.  That location is further complicated as slab edges  often are not straight.

    So, layout crews tend to “cheat” the line to miss the columns, moving back in on the floor slab to miss the columns.  One of the things the field crews usually discuss with the GC when they first hit the job is:  How much room are we going to need for layout and material storage around the perimeter of the floor?

    Layout in plan is one facet of this, but the layout crew also has to deal with vertical tolerance.  If you’ve ever stood at the base of a tall curtainwall and looked up, it’s surprising to see how straight the wall is (it’s a perspective you can’t get when standing away from the building, taking in the whole of it).  The in/out plumb of the wall can only be seen from that vantage point, or possibly from the other end, on the roof looking down.  It’s a sign of how good the layout crew was.  Specifications often limit plumb deviations to less than 1/8 inch per floor.  That’s a lot.

    It’s always been a minor miracle to me that more buildings and curtainwalls don’t crash into each other.  BIM can help model this prior to start of the work, but when the building actually starts, theory becomes reality, or should, anyway.  Granted, tolerances and designed-in allowances accommodate that, but when a steel structure is erected with tolerances of +/-2” or more, and curtainwalls being built to +/-1/32”, why don’t they bump into each other more often?

    And concrete’s even more challenging than steel in this regard.  At least with steel, you can work from fixed dimensions every time, but concrete’s formwork is repeated over and over again for the height of the building, allowing just a small mistake to have serious repercussions.

    And the horror stories about having to chip concrete to allow a mullion to go by are out there.  In one project I heard about, crews had to chip the concrete floor beam so far back, they had to cut through the rebar, also.  I’ll bet the project structural engineer loved hearing that.

    Typically the 1 ½- to 2-inch tolerance between face of slab and back of wall system is cheap insurance.  It gives the general contractor (GC) some flexibility with the edge of the slab, and allows the curtainwall to accommodate any variance without having to notch slabs.  Anything smaller than 1 ½” ends up with notching requirements later.   Architects don’t like it, as they don’t like to think about how to close off the gap.  But it’s a necessary “evil” which permits an easier installation of the wall.

    Having the discussion with the GC prior to work starting, usually as part of the pre-installation conference, is a good place to get all this figured out.  For example, what the structure erection tolerances are, what the curtainwall anchors can reasonably expect to accommodate for the structure tolerance, and what to do when the inevitable clash occurs.  It may be beneficial to have this discussion as soon as possible after contract award so that everyone, GC, framing sub and glazing sub all get off on the right foot, knowing where everybody’s supposed to be when the wall starts to go up.

    It will be interesting to see who among the curtainwall subs will be the first to set up a robot to do layout work…

    Answer to previous trivia:  CCNY, 1950. They beat the same school both times, and since I know some Bradley grads, I won’t mention who it was that lost both tourney championship games in the same year.    

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  • Field Notes 11.04.2013 2 Comments

    I’ve been picking up some vibes that USGBC’s LEED program might be coming under additional scrutiny. Namely, that the credits aren’t delivering the intended performance, or that some of the rating system needs to be revised.  Third parties such as the Dept. of Energy are looking into how buildings perform compared to their design.  Since LEED certification is basically developed during the design, the actual performance is not considered.  I couldn’t agree more with looking into the final results, since the design is only half the battle.  If the design and credits don’t lead to actual performance, what’s the point?

    The preacher will tell his flock, “The road to hell is paved with good intentions.”  The point is, the battle is won in “walk the talk.” This is where LEED falls short.  In some ways,  it’s too short-sighted, especially when it comes to life cycle issues.  I get that credits like the use of regional materials obtained within 500 miles of the job site are good, but what about longer-term things, such as what happens to the glass when the building eventually comes down, or is replaced?  Shouldn’t the ability to recycle a product at its end of life be taken into account also?

    Presently, tinted or insulating glass units aren’t recycled; they go to the landfill.  The reflective film on low-E glass isn’t easily removed, and spacers on IGUs are a bugger to unconstruct to recycle the glass.  I saw a building in Dallas not too many years ago imploded with glass still on the façade.  It was cheaper to leave it there and send it to the landfill than to pull it off and recycle it.  Even the curtainwall aluminum could be pulled out of the rubble and recycled with the steel and concrete, but not the glass.

    In a different industry, I recently heard about a newspaper that donated its unused paper stock to an animal shelter that used it to line kennels.  Okay, I get that paper is a renewable resource.  The question, though, is how much energy is expended making new paper compared to recycling it?  Because, once that donated paper is finished in its second life as kennel liner, I gotta believe it’s NOT going to be recycled, but will instead be headed to the landfill.  The point is, let’s think the whole life cycle out, not just between any two points somewhere on the time line.  In some respects, I don’t think LEED does that.

    What about requiring buildings to work as intended in the credits taken in the LEED certification?  Makes sense,  the building ought to “walk the talk.”   It can’t be a bad thing to ensure that happens.

    Maybe the LEED rating ought to include an evaluation period after the Certificate of Occupancy is issued, and the building be judged on how well the intended LEED credits and solutions actually perform before a rating is given.

    College Hoops Musings

    I didn’t know what I was in for.  Go! If you ever think about attending the college basketball championships, even for a second, just GO!  I don’t know if it was because it was the 75th championship, or that the games were all good.  But, my oh my, what an experience!  Kudos to the folks in Atlanta, they ran a classy, southern hospitality, no-holds-barred operation.  If you’re a fan of the game, you cannot miss an experience like this.

    A guy across the aisle from us was a Wichita State fan who brought his 10-year-old twin sons.  What an experience, and they stayed until Monday night, even after their team lost on Saturday.  All the fans sitting around us were just fun; they were there representing every team.

    And if ever a team I want to see win gets in, I’ll definitely go back.  I’d miss the Super Bowl, even if the Eagles make it, just to go to one of these again.  The heartache if your team loses, so be it, but what a ride!  Maybe not having a team at the dance made it enjoyable.  But if you have a chance, do NOT hesitate; like the Nike ads say, “JUST DO IT!!!”  So a big thanks to Jeremy for taking me.

    P.S. Trivia:  do you know the only team to win both the NIT and NCAA in the same year?  Hint: 1950. 

  • Field Notes 03.04.2013 2 Comments

    The Glass Association of North America’s (GANA) Building Envelope Contractors (BEC) Conference has come and gone, with some good ground covered. A high point was when Guardian’s Scott Thomsen gave a strong call to action for our industry in his presentation the “Battle for the Wall.”  The key takeaway was if we don’t fight for the role of glass in energy-efficient construction (thermal performance and daylighting), then ASHRAE will force us to the sidelines. Do you want to go to work for the stud wall, stucco and masonry contractors, because ASHRAE’s current emphasis is to greatly downsize the percentage of glass in exterior walls?

    We as a glazing industry should be showing architects  there are many glazing products that WILL increase thermal performance.  Architects will help us win this war, but only if we get smarter about educating them on the newest, most innovative glass and framing products now available.

    We should also be assertive with noting the other construction types have as many problems, as well, that are now coming to light in this energy-conscious age.  As ATI’s John Runkle noted in his presentation on building commissioning, these are things the glazing industry has dealt with for years.

    Notably, when the surrounding wall systems – cavity walls behind masonry or panels, precast panels, or whatever construction –  have to start meeting the same water and air penetration requirements as windows and curtainwall presently do on a regular basis, then that bodes well for the exterior skin, as a whole.

    But there are some down-sides, too.  For example, testing the weatherproofing/air barrier to the AAMA and ASTM standards for water penetration  aren’t  realistic since it never sees that amount of rain in the finished condition if a brick or panel wall is placed over it.  Air test it, yes. But a full-blown, 5-gallon/hour/square-foot water test ON THAT SURFACE isn’t real-world.  Some of this is still in the developmental stage, but I expect it will catch on in one form or another.

    Does commissioning make sense for a total glass curtainwall? Probably not with the current regimen of pre-construction and in-field testing required in curtainwall and window specifications.  There are some that would argue the call for increased testing is an effort by the labs to create more work for themselves.  Yes, I can see that, but what good is it having an air- and water-tight window or curtainwall if the wall around it doesn’t perform equally as well?

    Another high point at BEC was the presentation on Chinese tariffs. Some of the USGNN.com newsfeed had comments from the Chinese manufacturers’ side of the fence that felt the presentation didn’t accurately present both sides of the argument.  That wasn’t likely to occur given the fact the person making the presentation was the plaintiff’s attorney.  When’s the last time a lawyer led a fair, objective and balanced viewpoint on something his clients were paying him to have just the opposite opinion on in order to properly argue their case?  But, the tariff issue is going to be in the news quite a bit going forward.

    One last note:  Having turned the odometer over on my age this year, my brother bought me opening day tickets in Philly next Friday.  And, my no. 1 son bought us Final Four tickets.  Only one drawback to the venue:  basketball was not meant to be played in a football arena, unless they put the court in the end zone.  When watching the game, the Philly Phanatic sitting down the right field line in the KU garb, or in the corner of the end zone in Atlanta with the biggest pair of binoculars known to man will be yours truly.  This is one thing I’ll be able to cross off the ol’ bucket list.  As I review this blog post one last time Monday morning, I hope Wichita can shock the world.

    Here’s hoping the Easter season, with the accompanying onset of spring weather, brings renewal of faith, hope and charity to you and yours.

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