False Solutions Won't Stop Water
The rain found me yesterday. I was sitting in my kitchen enjoying my morning coffee when the streaming drips reminded me that I had ignored those curling shingles and cracking tar patches on the roof for far too long.
So I drove to the local golf shop and bought one of those really nice 64-in.-dia double-shell wind-vented umbrellas. It was expensive, but the salesman told me it was worth the cost because it was the best way to stay dry. Thanks to my fancy new umbrella, I can now stay completely dry as I sit in my kitchen.
Okay, I’m kidding just a little bit. I did actually buy one of these great umbrellas, which I use for my walks across windy downtown Chicago in the rain. It works quite well. But to stay dry in my kitchen, I called a contractor who did a fantastic job of replacing my leaky old roof.
My new umbrella and my new roof are appropriate solutions to their respective problems. The umbrella wouldn’t have really done me much good in my kitchen. Yet there are people who want you to buy their umbrella in response to your leaking roof, which brings us to a serious issue in the building industry today, the inability of exterior wall systems to keep water out of buildings.
Leaks cause problems. The structural frame is at increased risk, whether it is made from steel, concrete, masonry or wood. In the first three, the steel, whether wide-flange shape or reinforcing steel, will rust. In the fourth, the wood will rot. There is simply no avoiding these eventualities if water enters the building. Yet one recent response to this problem was to suggest painting perimeter steel in order to provide corrosion protection (ENR 6/9 p. 38). While this may bring a degree of comfort to building designers, contractors and owners, it is a false solution.
In building structures, steel need not be primed or painted if it is enclosed by the building finish, coated with a contact-type fire-protection material, or in contact with concrete.
When enclosed, the steel is trapped in a controlled environment and the products required to permit corrosion are quickly exhausted–unless the facade leaks.
Section M3 of the commentary to the AISC Specification for Structural Steel Buildings states, "The surface condition of steel framing disclosed by the demolition of long-standing buildings has been found to be unchanged from the time of its erection, except at isolated spots where leakage may have occurred. Even in the presence of leakage, the shop [primer] coat is of minor influence…." In short, where there is water, damage is inevitable.
Facade problems need facade solutions because leaks have devastating consequences beyond the structure. Interior finishes will stain and disintegrate. Electrical and mechanical systems not designed for wet environments will fail. Insulation will be ineffective. And mold will grow. In terms of immediacy, these problems are far more contentious than corrosion. Yet painting perimeter steel will do nothing to solve them.
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Keeping the rain out is perhaps the most important–if not, the most basic–service an architect performs in the selection and design of the facade system. Proper enclosure within a facade is paramount. So let’s use properly performing facade systems and fix a facade that fails. The pursuit of solutions that do not involve the integrity of the facade system is akin to the old joke about looking for the lost quarter where the light is good, rather than where it was lost.
The facade and gasket industries have taken significant forward steps over the past decade to minimize facade leakage problems. The details and technologies of the mating of facade and structural systems have also progressed significantly. Now, it’s time to take further steps and reach a true solution to the problem. We simply cannot just open our umbrellas to stay dry in the kitchen.