Changes in environmental forces drive mold growth.

(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.

Once we rely on these wonder materials and technologies to perform building functions rather than relying on the architectural elements they replaced, the next logical step is to entirely remove the functional role once played by the architectural elements. Architectural elements without functions are, by definition, ornaments. They have no function except to please the eye. They no longer have an inherent context in which they must exist, and therefore can be applied anywhere where it pleases the eye.

The same holds true for architectural styles. Once, styles were specific to a certain place. But the ornaments that identify the style have had their functional role removed, so now styles can be used anywhere. It is not unusual, and in fact it is the norm, to find buildings of all styles from all historical periods and different environments plunked down cheek-by-jowl in the same development. There are cultured-stone Italianate villas next to brick-veneered Tudor homes; vinyl-sided carpenter gothic bungalows next to Styrofoam adobes. Functional ornamentation and style, once the result of necessity, have become options.

So what? It has made us lazy. It is relatively hard and expensive to build buildings which function well without the high-tech bandages that we now rely on. Easier and cheaper to rely on sealant, and just make the building look like we want it to. But the pretty trim on the front of a house or the stone watercourse at the base of a building was there to function, not simply to please the eye. And very often the function of the elements was to prevent the introduction of water into the building. Pitched roofs, clapboard siding, deep overhangs, elaborate window trim, and other devices that delight designers today all evolved to keep the interior dry. Dry houses and dry buildings don't grow mold.

Once architectural elements lost their functionality, the understanding of how and why they functioned was lost. Architects and builders were freed of the requirement that they understand how buildings function, and were free to simply decide how buildings look.

Many Architects have become designers of pictures of architecture, not designers of Architecture. Their product pleases the eye, but they do not function properly.

The lack of knowledge of the utilitarian underpinnings of the elements of architectural style has resulted in the creation of architectural time bombs in every community in America. The symptom of the time bombs is mold. The cause of the mold is unmanaged water in the building environment.

Don Erwin, R.A., a vice president of LZA Technology, is an architect specializing in forensic investigations and analysis of existing building performance. Drawing on 25 years of industry experience, he frequently provides litigation support as an expert witness in legal proceedings, including those related to liability and damages associated with mold contamination.