Changes in environmental forces drive mold growth

Real Estate Weekly, May 5, 2004 by Don Erwin

(The following is Part Two in a seven-part series on the growing rate of mold detection, remediation projects and litigation in the US presented by the experts at the Environmental Health services group at LZA Technology, a division of The Thornton-Tomasetti Group.)

One of the most influential analyses of American construction is James Marston Fitch's "American Building: The Environmental Forces That Shape It". Fitch explores how buildings were designed and built in the past in the United States, and suggests that to a large degree the forms that buildings took in the past were largely the result of reactions to the cultural and natural environment around them.

The natural environment is obviously one of the major forces.

For example, in the hot moist south, houses were made of thin wood clapboard, had large openings and deep verandas, and steeply pitched roofs. This is because air movement and shade were the means of maintaining a comfortable living environment, and because there were intermittent torrential rains. Wood was plentiful, so houses were made of wood. In contrast, in the hot dry southwest, the houses had thick massive walls, very small openings and flat roofs. This is because massive walls remained cool during the day and warm at night. Small openings prevented sunlight from shining indoors causing it to become heated.

Since there is little rain, there was no need for steeply pitched roofs. Adobe and stone were plentiful, and wood was scarce, so houses were made of adobe and stone. In the Northeast, clapboard was originally needed to cover over the medieval styled "wattle and daub" buildings of the original settlers. The mud walls of those buildings tended to melt and rot away without the waterproofing layer of clapboard.

Over time, the characteristic colonial style building evolved that did away with the timber and mud behind the clapboard, and developed a large central hearth structure that provided heat for the entire home. Relatively large windows let sunshine in during the winter, and shutters prevented it from entering during the summer. Similar examples can be drawn from all of the various environments across the country.

But traditional architecture was not shaped simply by a pure response to the natural environment. It was also a reflection of the cultural environment in which it existed. So buildings in the same region were similar in their response to the natural environment, but may vary widely in the "style" in which they accomplish it. For example, old buildings to the south and west of Philadelphia do not look like those in Philadelphia, in part because the Swedes brought their architectural traditions to the area to the south and west, and the British brought theirs to Philadelphia.

Or for example the Victorian mansions of Albany do not look like the buildings in the Shaker communities a few miles away that were built at the same time, because one culture celebrated wealth and the other celebrated simplicity. Although they responded to the same natural environment to provide an acceptable living environement, the style in which they accomplished it differed widely.

There is an architectural cliche that dates at least as far back as the 19th Century French architect and theoretician Violette le Duc, which asserts that all of the various ornamental details we take for granted in classical architectural styles are vestiges of previous functional elements.

For example, the various parts of a classical cornice, all the clutter of dentils, triglyphs, metopes, guttae, architraves and other obscure objects, are merely the vestiges of the ends of roof rafters, the beams on which they rested, pegs to hold them in place, and so on. While this may be interesting for architectural historians, it is also a relevant analytic tool to consider when we assess current architectural practice, especially in residential construction.

The ornamental gee-gaws that make the exterior of buildings "interesting" today once were there "decorating" the buildings because they had functional roles to play. For example, elaborate ornamental trim around Victorian windows originated as a functional necessity. Wood planks inserted around the window openings served to keep water out of the walls. The simple trim was carefully and painstakingly shaped so that it integrated into the building framing and siding to shed water. Over time, they became more and more elaborate, until they appeared to have an ornamental life of their own.

Today, it is not unusual to find highly ornamental window trim that is just nailed to the surface of a building without any water-shedding function at all. And many times, nothing is installed at the window to replace the water-shedding function of the trim. Or, more correctly, nearly nothing is added to replace the function of the trim. There might be a smear of caulk around some of the joints, maybe a sheet of plastic somewhere in the wall. Admittedly, it is the hard thing to do to understand how the trim functions, and to integrate a carefully shaped piece of wood into the building fabric. Easier to rely "wonder" materials like silicone, plastic, polyolefin, and polystyrene to somehow hold the environmental forces at bay, at least for a while.