• Field Notes 29.02.2012

    How often does one get to write a blog that’s going to be published on leap day? Someone out there’s probably going to say, “once every four years, dummy.” So, how come this is the first/only one I’ve ever written? And let’s just leave it that more than 14 leap years have passed before I got to write this one. And, a few weeks have passed since my last post on condo curtainwall, but there’s much more to say.

    So much has occurred recently in the news. Two of the glazing industry’s more reputable firms announced over the last few months that they’re shutting down. My, how the mighty have fallen! One of them is back up and running, it appears. Here’s hoping the other one will become this year’s Phoenix. One would have thought the 2009-2011 stretch would have buckled them long before, but now, when things appear to be looking up? The blogs are full of concern for their people. Please add to that list our thoughts, and prayers this will be short-lived, a minor roadblock for them and their families. But it can’t seem like that right now …

    The Super Bowl’s come and gone. Laying the SI with the Giants on the cover on the desk of the diehard Pats fan in the office was payback in the max for them beating the Eagles in the Birds’ last trip to the SB! March Madness is gearing up. Kansas hasn’t been playing well of late, but Saturday’s win over Missouri was a heck of a win (except if you’re a Mizzou fan)—Vicki rarely sits and watches the whole game, but she did Saturday. ESPN’s show, “The Sports Reporters,” argued how much the regular season in college basketball sets up March Madness, and, looking forward to the tourney, they asked the question, “Can’t something be done to get this craziness into college football?” Baseball spring training is opening, and hope springs eternal, again.

    My last blog left off talking about condo glazing issues; I’d like to resume that discussion, and call it “Floor Slab Problems Continued.” Here goes:

    Many older condo projects leave the slab edge exposed, as discussed previously, on the exterior perimeter of the building, instead of recessing the slab edge and letting the curtain wall run by. Leaving the slab exposed creates a heat sink or fin open to the exterior elements. Heating the building interior, with the slab edge un-insulated and exposed, creates an escape point for that energy. For better energy efficiency, many condo details now include an insulated slab edge cover that reduces heat loss.

    Because of the thin slab being extended to the exterior edge of the building, instead of designing a curtain wall, the architects will frequently use window wall systems that extend from the top of the lower floor slab to the underside of the slab above. The walls are anchored at the base to the lower slab, and a head can (i.e., an assembly with a head horizontal slip fitting into a second, channel-shaped extrusion that accepts dimensional limited but significant dimensional changes) that is able to handle slab forming tolerances and window wall expansion/contraction is erected at the underside of the floor. This creates three additional points for leaks to occur as compared to typical curtainwall construction. There are two sealant joints at the head and sill, as well as the joints required in the head can/window wall transition. These are in addition to the frame-to-frame, glass intersection joints typical to any curtainwall or window wall construction.

    The sill joint usually can be typical, but the head can and/or the sealant joint above it must sometimes be larger than what the architect originally detailed. Due to the tolerance in forming the concrete, the slab location might be off as much as ¾ inch or more from that shown on the architectural details.

    There’s one other set of slab issues to deal with, which I’ll tackle next time.

    By then the college basketball brackets will be out. And hopefully, KU won’t go out like they did in the early rounds around 2008, when they won it all. Losing to VCU, or Butler, or other second-tier schools is just way too hard on the ticker …

    Posted by Blogger @ 11:49 am

  • Leave a Reply

    Your email address will not be published. Required fields are marked *

USGlass Magazine

USGlass Magazine