THE FIFTIES AND SIXTIES
Looking back to the 1950s and ’60s, the construction industry was primarily made up of union workers with 85 percent of the total work force coming out of apprenticeship systems. The flashing curriculum was taught and used universally. Since the lathers and carpenters were the predominant driving force, these trades had a major impact on making buildings work.
Architects used vellum paper and pencils, creating elevations and details with a better sense and feel where each layer of material was placed and why. Buildings were also simpler in design and generic materials were used to construct them. If an architect made a mistake on paper, the apprenticed field trades were able to fix it on site.
Energy was cheap and buildings were anything but airtight, so buildings breathed naturally. The aluminum nail fin window came onto the market; the rigid attachment fin allowed for a shingle-style flashing paper and was perfect for the residential market.
Buildings were put up with the aid of sheet metal contractors who installed flashings, Z bar and weep screeds to ensure water-tightness. Plastering contractors had one exterior cladding to work with and that made the learning curve more forgiving. Commercial buildings had storefront windows with metal sill pans. Life was good and not too complicated.
Starting in about the late ’70s and well into the ’80s, the trade unions began to lose market share at an alarming rate. Apprenticeship slid until only a small percentage of workers came out of that tradition. The new breed of workers felt the flashing procedure was unnecessary. Architects started to draw with computers and classes had to shift to this new technology. Something had to give way and it did-adherence to basic construction details.
Energy costs climbed, new laws required tighter buildings with vapor barriers, resulting in buildings that did not breathe as well. That, combined with the lack of flashing, was a recipe for disaster. General contractors began to move away from field promotion and went to colleges for personnel. The new workers lacked in-the-field technique but had the ability to push construction schedules for faster completion. During this time, building designs got more complicated.
Subcontractors had expanded roles as sheet metal contractors were considered non essential. Plastering contractors had to learn more cladding systems than just the one and as the number of options kept growing, the moisture management principles changed. Storefront installers stop using sill pans; vinyl windows had wavy and easily breakable plastic fins. The perfect storm had come together to create a leaky building crisis.
THE NINETIES AND 2000
The 1990s saw the advent of construction defect experts. They opened up buildings, documented the decay and presented their finding to the insurance companies covering both general contractors and subcontractors. Since the insurance companies were making money hand over fist with investments, they paid these claims out without giving up much of a fight. As investments turned sour, the flashing practices of the trades improved and there was better quality construction all around. By the mid-2000s, the insurance companies decided to start fighting back. The forensic experts and attorneys found the new road not as easy as they had the decade before. As forensic experts starting losing cases, the fear spread over the industry and created another opportunity for them. They would shift to the front of the project to become envelope consultants.
There is an abundance of scientific data on vapor and moisture control for exterior wall assemblies. It is possible to ignore common sense in an effort to sell products or services to solve the basic problem of how to make a building weather-tight. In reality, most building problems with regard to moisture intrusion can be traced back to a failure to follow some basic, time-proven design or installation practices with regard to good flashing. These aren’t old hand tips or trade secrets-they’re recommended industry practices and standards.
While I cannot predict the future, it is hard to imagine that we could get more complicated designs, more costly construction or more convoluted in basic flashing details. What is needed is a return to sensible details, better trained workers who install them and walls that work for the masses.