The Great Drywall of China (Part 3 – Unpublished)

Until this problem is resolved, homeowners living with contaminated drywall have a limited number of options.

The most obvious – and potentially damaging – reaction is to paint over the drywall with an impermeable material like oil-based paint. Walls are specifically built to “breathe” so that they do not trap moisture vapor in the wall cavity. There is already a vapor barrier (typically a house wrap) on the exterior wall underneath the siding, so adding an indoor vapor barrier (such as an impermeable oil-based paint) would leave the water nowhere to go. In our climate this is a sure recipe for mold and moisture problems.

The first step in controlling the problem is to create positive indoor pressure. This reduces the amount of volatile chemicals drawn from the drywall. The volatiles may still off-gas, but they will do so more slowly and in lower amounts than if the indoor space is in negative pressure. I’ll talk more in-depth about positive pressure in the next blog.

Another good measure is installing a dehumidifier to regulate indoor relative humidity. Volatiles react more vigorously in high heat and humidity. Controlling the amount of moisture in the air will help control the problem.

Lastly, consider adding ultraviolet lights in-line with the HVAC system and in individual rooms. Ultraviolet lights designed to destroy volatile organic compounds will reduce harmful gases to inert materials.


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