Looking at a building can be a lot like looking at the human body. From outward appearances, everything may seem just fine, but sometimes trouble brews beneath the surface. Insidious forces like wood-ingesting insects, fungus, mildew and mold have the potential to wreak serious havoc on the building and the health of its occupants.
Pressure-treated wood is a building solution often used to guard against decay and termites. In specialized factories, lumber is subjected to a chemical preservative that bonds with the wood. The fact that the wood lasts longer offers some environmental advantages because it reduces the number of trees harvested and decreases transportation impacts. Unfortunately, pressure-treated wood still is subject to the effects of moisture, and that was the obstacle Charles Morando, president and chief executive officer of Boca Raton, Fla.-based WoodSmart Solutions Inc., set out to conquer.
“I was interested in creating a product that would offer protection from mold growth for the complete residential and commercial structural framing package, and I wanted to offer the marketplace a green alternative to some of the chemicals used in pressure-treated woods,” Morando says. This interest led to the development of BLUWOOD in 2003. BLUWOOD’s benefits have provided it with quick traction in the construction marketplace, but like many other pressure-treated wood products, concerns have been raised about the product’s interaction with metal.
A History with Fasteners
Scott Kriner, president of Green Metal Consulting, Macungie, Pa., and technical director of the Metal Construction Association, Glenview, Ill., says that many of the older processes for pressure-treated wood contained copper chemicals that were corrosive to zinc-coated fasteners. Newer products lowered or eliminated the copper component, but some replacement chemicals may still cause corrosion of metal fasteners. Left unchecked, premature corrosion of fasteners could potentially jeopardize the integrity of the fastened system. To help address this issue, MCA has issued a technical bulletin on its Web site, www.metalconstruction.org, regarding the selection of fasteners for use with pressure-treated lumber.
In 2004, Conyers, Ga.-based Timber Products Inspection Inc.—a third-party wood products inspection, testing and consulting company—conducted an independent study that concluded BLUWOOD does not produce a pH level corrosive to metal fasteners and plates. The study was performed during a 10-day/240-hour test.
Posing a Question
In the case of BLUWOOD, however, MCA’s main focus is on the possible corrosion of metal roofing. The issue surfaced last year when the state of Florida considered passing a law that would require the use of pressure-treated wood in all residential construction because its resistance to rot and termites is especially beneficial in hot and humid climates. Originally considered under Florida’s “Glitch Codesuggestions that the state generally considers minor, editorial or inconsequentialthe possible law was ultimately dropped as the state ruled that the issue did not meet the definition of a Glitch Code.
Despite the dismissal, MCA realized that if the law was to pass in the future, BLUWOOD’s growing popularity, evidenced by multiple appearances on ABC’s nationally televised show, “Extreme Makeover: Home Edition,” made it a likely candidate for use. In addition, unknown factors about BLUWOOD’s performance under conditions of prolonged exposure to moisture have MCA wondering what it might do to metal roofing.
“We’re uncomfortable about the potential for product reaction if BLUWOOD is subjected to moisture over time,” Kriner says. “Metal roofing will perform well for 40 to 100 years depending on the substrate involved, and with BLUWOOD, it’s the lack of long-term data that gives us pause. We are looking for either accelerated or real-time testing that would simulate corrosion performance for possibly 10 years.”
Credit: J. Ciarlante
According to Morando, accelerated laboratory studies simulating BLUWOOD’s long-term exposure to elements and any possible outcomes on metal have not been conducted before because the company’s emphasis always has been on interior structural framing.
The Space Between
Kriner says that regulating the use of pressure-treated wood for all residential building systems means that BLUWOOD might be used for batten systems used beneath modular metal shingle roofs. Although a membrane usually keeps water out, there always is the possibility of slight leakage.
BLUWOOD warranty information states that the wood components cannot be used for permanent exterior exposure or for an interior space that creates an exterior environment without a top-coat application of an exterior grade paint, sealer or exterior stain. Further product information says that BLUWOOD must not be left unprotected from the effects of weather exposure on the job site beyond six months. MCA is curious to know what might happen after six months of moisture exposure and if the result might have an adverse affect on metal in close proximity.
Morando says the provisions are there as a precautionary step to limit liability. “BLUWOOD covers a very wide spectrum of grades and types of lumber, such as oriented strand board and plywood,” explains Morando. “These all have different reactions to weather exposure.”
Something New
What makes BLUWOOD different from standard pressure-treated wood is its resistance to mold and mildew. BLUWOOD’s two-part process forms a coating that cross links with the cellulose fibers in the wood at the molecular level during absorption and curing to form a sub-surface water repellant. A moisture-vapor permeable film slows the rate at which moisture vapor escapes the wood to help reduce curling, twisting and cracking. A second preservative protects against rot fungi and wood-ingesting insects, including termites. The fungicide is a Washington, D.C.-based U.S. Environmental Protection Agency registered component, which means the ingredients will not have unreasonable adverse effects on humans, the environment and non-targeted species.
In the fall of 2007, the Louisiana Forest Products School of Renewable Natural Resources, Agricultural Center at Louisiana State University, Baton Rouge, performed testing on BLUWOOD for volatile organic compounds in accordance with EPA Method 24—Surface Coatings, and found that BLUWOOD had a VOC content so low that it can be considered to have no VOCs.
The product’s coating is clear, but tinted a teal-blue color to make it easily identifiable. Unlike many pressure-treated woods, the product has no special handling requirements and it can be recycled or disposed of in the same way as non-treated wood.
Despite positive results so far, Kriner says the product has not been on the market long enough for MCA to be reassured that it will perform well with metal roofing. In addition, if Florida was to create a code requirement to use the pressure-treated lumber for all residential construction, it would increase costs to roofing contractors.
Financial Implications
Credit: J. Ciarlante
Kriner says virtually every manufacturer in the metal roofing industry has some business in Florida because it’s such a popular product in that state. He notes that metal roofs have a particular appeal in a swath across the southern U.S. states that he calls “the calamity belt,” which includes California, Florida, Louisiana, Mississippi and Texas. These states are subject to high winds, hail, wildfires and seismic activity, and metal performs well in dire circumstances.
“Metal roofing offers hail and wind resistance in a hurricane. It is non-combustible so it performs well in wildfires and it is lightweight, which is important during a seismic event,” Kriner explains.
Metal has gained a lot of ground in the past eight years, rising from less than a 3 percent share of the residential marketplace to a 10 percent share. Pressure-treated wood like BLUWOOD is more expensive than untreated wood, which would add costs for roofing contractors. If BLUWOOD required an additional exterior sealant for protection, that would add another layer of cost as well.
Next Move
Kriner says MCA believes that BLUWOOD is a great product for framing systems. When it comes to batten/counter batten systems, however, the association wants more proof that there won’t be a long-term problem before codes and building inspectors begin to require it. MCA is considering some testing of the product and hopes to conduct it in cooperation with BLUWOOD.
Currently, the Chippewa Valley Technical College, Eau Claire, Wis., which is part of the University of Wisconsin system, is conducting a flood test on a house structure built with BLUWOOD to train individuals and insurance professionals about how to return the structure and contents back to pre-loss condition within a few days. Since February, the test has flooded the structure with 1,500 gallons (5678 L) of water once or twice a month, and Morando says reports show no corrosion problems with metal plates or anchors.
Nonetheless, Morando says he also would like to partner with MCA to perform accelerated testing. “If they do eventually change the code, it’s important this area of the market has peace of mind,” he says.
KJ Fields write about architecture and metal construction from Portland, Ore.