New building materials create challenges
Architect About Town - Special to the Fort Myers News-Press
A thousand years from now, archaeologists exhuming the ruins of buildings will notice that they suddenly began rotting at an alarming rate during the second half of the 20th century.
The culprit will have been air conditioning combined with sophisticated innovative materials — a terrible thing done to these structures. Modern materials used haphazardly cause more harm than good. Air conditioning can be to buildings what steroids are to our bodies — an instant improvement that can cause permanent damage.
Before World War II, buildings were constructed from materials found in nature: stone, trees, clay, lime, sand and sometimes horsehair. Boards were cut from logs in the woods. A trip to the general store for nails, tar and paint completed the job.
Inevitably, buildings “breathed.” Moisture seeped in but was also able to dry out.
After World War II, man-made goods began to replace natural materials. Gypsum board replaced lath and plaster. Plywood replaced wood boards. Metal studs replaced wood. A little later, house wrap replaced tarpaper. Vinyl and aluminum replaced the wood in windows and walls and roofs were insulated. For good measure, a layer of plastic or polyethylene — the “vapor barrier” — was installed inside almost everywhere.
Notice most of this stuff came in large sheets that sealed up buildings so they could no longer breathe, nor were they very absorbent. New-fangled energy-efficient materials like the insulation, windows, lighting and appliances saved money on utility bills but deprived the building of the heat and ventilation badly needed for drying. Water not only condensed inside the now-cooler walls, but it couldn’t escape and it couldn’t evaporate.
It should be mentioned that building materials didn’t develop in parallel, either. Each manufacturer was selling his particular piece of the puzzle and laid claim that his product was the greatest thing since TV dinners.
Building components were replaced one by one, but no one understood the big picture. Each piece did its part but didn’t necessarily serve the interest of the building as a whole. Rot set in. So did mold. It was like Dixieland jazz where different melodies were being played at the same time.
Buildings aren’t jazz, though. They’re more like a symphony.
We began to cool buildings around the same time, but air conditioning wasn’t integrated. It was an afterthought. The air conditioning industry didn’t talk much to construction people other than to argue about space for ductwork.
It gets worse. High performance insulation and sealing cold air ducts at once increased the potential for moisture to occur and diminished the ability to dry out, creating more condensation. More cold. More rot. More mold.
Fortunately, things are getting better. So too is our understanding of how to build in a hot, humid climate. Attics are now sealed with foam insulation, less polyethylene is used and high performance air conditioners are paired with old-fashioned dehumidifiers.
Space Age coatings on glass block cut 75 percent of the sun’s heat without hindering views or distorting color with unnatural tints.
And there is a return to age-old principles of vernacular architecture, which reduces energy consumption. There’s considered orientation to minimize heat gain at the outset while, weather permitting, shade and cross ventilation allow cooler air to circulate and excess moisture to evaporate.
Incorporating newer systems into a well-designed building while avoiding unwanted condensation and mold require the services and expertise of skilled professionals.
Anyone can go to a big box store and buy plywood or weather stripping, or get advice on double-glazing or vinyl siding, but all these pieces must be holistically integrated to maximize their effectiveness.
Making all this work in concert is like composing and directing the symphony. And the conductor will be your architect though he/she may need an HVAC (heating, ventilation and air conditioning) engineer to help turn the pages.
Joyce Owens AIA RIBA