What is a VOC anyway?

VOC is one of the most widely used acronyms in building today, but most people can’t define it. A VOC (volatile organic compound) is a carbon-based chemical compound that evaporates at room temperature. Gasoline is a VOC because it’s a hydro-carbon and fumes pour off it at nearly any temperature.

How did VOCs get in building products? For products that dry or cure — like caulks, sealants, adhesives, paints — they have to be applied in liquid form. To make paint, urethane, rubber and glue into a temporary liquid so it can be applied, you need a solvent. Until these products were re-engineered to use water as a solvent, many manufacturers used (or still use) solvent chemicals that are VOCs. For instance, if you want a rubber sealant between a window and a stucco wall, you can’t apply stiff rubber. So, the rubber is liquefied with xylene or benzene, both petroleum derivatives, and both VOCs. The VOCs flash off (evaporate) to leave the stiffened rubber behind. Unfortunately, when VOCs flash off, the fumes can enter people’s lungs, living spaces and atmosphere, and that’s when the trouble starts.

VOCs can cause “eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to liver, kidney and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans,” according to the U.S. Environmental Protection Agency. VOCs also react with sunlight and the atmosphere to create smog.

Some products contain VOCs, yet they don’t get into the atmosphere at concentrations that are dangerous. Formaldehyde is one of those VOCs. A carcinogen commonly used in adhesives (plywood, MDF and batt insulation), formaldehyde in products that are low-emitting does not create a known health hazard. The Occupational Safety and Health Administration regulates formaldehyde and has adopted permissible exposure levels. Look for third-party tests to verify manufacturer claims that formaldehyde levels are safe.

You mostly find VOCs in paints, finishes, caulks, sealants and adhesives. Look for EPA-regulated claims of “zero-VOC,” or “low-VOC” as your greenest alternatives.

Rimboard Clarification

The caption for the picture of the Ainsworth Engineered 0.8E Durastrand OSL Rimboard in my April 2008 column “Kick-Start Your Green Practices” (April 2008, pg. 40) may have led to a misunderstanding. The caption stated: “Rimboards can be used without the need for separate headers,” but this wrongly suggests windows or doors don’t need headers if Durastrand OSL is used. Since 0.8E Durastrand OSL has been code-evaluated for use as a short-span header, and because it’s already being used as a rimboard, there’s no need to order “additional” header material (LVL or LSL) if you have Durastrand OSL on-site. The only occasion where a header could be left out would be when Durastrand OSL is used as the rimboard and there is a basement window, or opening, below the rim.