SAB HOMES 7 - Old day Plasters, New day Design

Even in the innovative and rapidly changing world of green building, some of the old ways and traditional materials are often the best. For thousands of years, natural clay and lime plasters have been used to create beautiful and long-lasting interior and exterior finishes. While these materials continue to be used extensively throughout the world, they have been largely replaced in North America by cement and acrylic stuccos.

By Peter McGee

The reasons for this are numerous but none are based on performance or aesthetic. The biggest setback to natural plasters actually came in mid 1900s when the Portland cement industry bought and controlled most of the lime-producing kilns in North America [a parallel to big oil and the electric car]. Subsequently it became increasingly difficult and costly to find natural plasters, and increasingly easy and cheaper to find inferior alternatives.

But then the inevitable happened. The cement stuccos cracked because they were too brittle, the acrylic stuccos trapped moisture, high-VOC paints created toxic indoor-air quality, and mould starting growing.

People started to wonder why their faux finishes felt faux and why their coatings were failing. The answer is simple, they weren’t using the right materials.

Lime and clay plasters share a number of characteristics that are perfectly suited to a finish material. Most importantly, both types of plasters are flexible and the “skin” of a building should always be more pliable than its structure [not unlike the human body]. The plasters are completely non-toxic, naturally mould resistant, breathable and also produce soft and rich colours and textures that actually improve with age.

So as is so often the case, we’ve gone full circle and there is a new interest in an old material. Companies are now importing Naturally Hydraulic Limes [St. Astier] and Venetian Plasters [Stucco Italiano], while others have started mass producing earthen plasters in North America [American Clay].

Applicators and designers have begun to incorporate clay and lime into modern design with stunning effects and the architects, builders and homeowners are once again recognizing the value and beauty of the old-world plasters.

Peter McGee is a Partner in GreenWorks Building Supply, www.greenworksbuildingsupply.com .

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