The lesser of two evilsConsider the two types of formaldehyde used for both interior and exterior composite wood building products:
- Urea formaldehyde: interior grade (water soluble)
- Phenol formaldehyde: exterior grade (insoluble)
Because of its ability to bond much more tightly to the wood fibers found in products, such as medium density fiberboard and particleboard, when used as a binder PF will off-gas much less than its cousin UF-the standard binder used for interior grade wood panel building products. That's good news for the interior environment where wood panel products are widely used and where pollution levels can be up to 10 times higher than the outdoor air and at concentrations up to 100 times greater. A recent government study revealed that fully 50 percent of all disease is directly attributable to interior pollution.
Years ago, chimneys drew fresh air into a house and pulled pollutants out but chimneys don't work well in tight construction which, in effect, has changed the pressure dynamics of the houses built today. For decades, the baseline level that builders have had to construct residential housing to was/is known as category two, which relies on natural ventilation such as drafts and open windows or "loose construction."
Nowadays, with tight, energy-efficient houses, chimneys must compete with other equipment, such as bathroom fans, downdraft cook tops, range hoods and dryer vents. Leaky supply networks of ducts or simply closing a door can pressurize or depressurize a room in a tight house.
Since 1994, the option for builders to construct houses to category one has existed. This higher level of construction intended for tight building envelopes supplements natural ventilation with mechanical ventilation-a must for tight buildings to draw out the pollutants. One wouldn't buy a car that relied only on rolling down the windows for fresh air. A mechanical ventilation system is standard, yet this is exactly what we do when we build a tight house to category two status. Many builders have incorporated features of category one but have failed to embrace it entirely due to the cost premium of plus or minus $4,000 to $5,000 for a mechanical ventilation system.
As mentioned in part one, the International Agency for Research on Cancer revised the status of formaldehyde from a probable to a known human carcinogen in 2004. Quite literally, our indoor environments are killing us. Sick building syndrome and building related illness are common phenomena in our homes and work places. The former (SBS), describes generalized symptoms, such as malaise and lethargy, while the latter (BRI), relates to a specific illness caused by the built environment (i.e. Legionaires' disease). Considering the widespread use of particleboard for casework and paneling, it's easy to understand how polluted the indoor environment has become-standard particleboard off-gases very significant amounts of UF.
Recognizing this fact, the USBGC's LEED green building rating/certification program offers credits/points for avoiding UF wood products entirely. Healthy building proponents recognize three major sources of indoor pollution:
- Combustion gases
- Synthetic building products
For the latter, particleboard with a UF binder is a particularly notorious example. Healthy building proponents also recommend a three-part strategy for building healthy, called "ESV":
The first, "eliminate," is the most effective of the three since, if the pollutant source is not introduced to begin with into the indoor environment, it need not be dealt with by separation and/or ventilation. It is a case of an ounce of prevention being worth a pound of cure. Phenol formaldehyde's ability to bond better and off-gas significantly less than UF is definitely a good thing, however we must remember the old maxim, "The lesser of two evils is still evil." With that in mind, Roseburg Forest Products, of Roseburg, Ore., has recently introduced a product called SkyBlend, which, though not the first, is the first conventional general-use particleboard commercially available to use a PF rather than a UF binder. There are other, specialized particleboard products that serve niche markets (more about them in part three).
The sky's the limitMade from western softwood fibers, SkyBlend maintains the same physical properties as UltraBlend particleboard-Roseburg's standard UF binder particleboard. They do not claim SkyBlend particleboard to be moisture resistant, however since PF is insoluble, a particleboard product, such as SkyBlend, made with PF is naturally more moisture resistant than particleboard made with standard water-soluble UF. To make it easily identifiable in the field, SkyBlend is given a light-blue tinting and is available in an industrial grade only. Custom size panels are available for larger orders and standard dimensions include seven thickness' ranging from 1/4 (6 mm) to 11⁄8 inch (29 mm). For 3/4- and 11⁄8-inch thick panels, larger size panels are available rather than the standard 49-inch-by-97-inch (124 cm by 246 cm) panel. Though it costs about twice as much as standard UF particleboard, SkyBlend is cost-competitive with other MDF and/or particleboard NAF products. It is not formaldehyde-free and does not make any such claim. However, due to the tight bond of the PF to the wood fibers, the product is nearly odor-free off-gassing about 0.04 parts per million when tested-about the same level as outdoor air. Standard UF particleboard off-gases up to seven-and-a-half times as much as SkyBlend and still meets industry standard specifications.
Roseburg's Dillard, Ore.-, plant has the capacity to produce 400 million square feet per year (40 million square meters) of particleboard (at 3/4 inch thick). One-quarter or 25 percent of the Dillard plant will be devoted to producing the panel (100 million square feet per year or 9 million square meters) if demand permits and it will be available through select distributors. Though the wood fibers used in SkyBlend are not Forest Stewardship Council certified, the panel is made from the post-industrial waste of lumber mills thus, it qualifies as being made from 100-percent recycled material. As well, the product has been GreenCross certified by Scientific Certification Systems. For more information on the product, visit www.rfpco.com.
In part three of this series, we'll examine some of the non-added formaldehyde composite wood panel products currently and formerly available on the market.
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