Mold grows on the cellulose-based paper that is used to cover the faces
of most gypsum boards. Most paper is derived from wood, which consists of
cellulose, lignin, and other polymeric structures. These organic substances can
serve as substrate for microbes, including fungi. That is, they not only provide
a place for these organisms to live and grow but also contain the organic
compounds that serve as the food sources that provide energy to the fungi.
Thus, the choice of using paperless drywall is one technique for reducing
the risk of mold formation. When paperless drywall is used, there isn't a ready
supply of cellulose for mold to grow on, so the risk of mold formation is lower.
Unfortunately, some paperless drywall requires the use of primers that have a
large amount of dissolved solids for plugging up holes in the finish. Primers
with large amounts of dissolved solids frequently contain lots of VOCs. So it
seems at first blush that one must choose between using paperless drywall and
using paints that have low amounts of VOCs.
The Home Depot Smart Home at Duke University Solution
Since VOCs are released during coating, the way to strategize for reducing
exposures is based on air exchange rates. Thus, the approach is as follows:
1. Use paperless drywall and prime it with a primer that has the minimum
recommended amount of dissolved solids.
2. Next, before occupancy, flush the entire building with fresh air every 3
minutes for nine straight days.
This approach takes into account that although VOC concentrations are highest
during the time of spraying, they will continue to be released from the sprayed
surface for some time. This two-step process flushes out any VOCs that were
introduced by the primer, making the air safer for inhabitants.
1. Draw a life cycle for paperless drywall versus paper drywall. How do
extraction and postuse differ?
2. What are the sources of volatile compounds indoors?
3. What does the mass balance look like for formaldehyde? How does it
differ from radon?
Source: This example was provided by Tom Rose, Director of the Duke Smart Home Program.