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More Wood Shake and Shingle Roofing Is Fire Retardant

Fire-Retardant Shake and Shingle Roofing Pass
Comprehensive Fire-Safety Test

February 12, 2003

(Ferndale, WA.) Market analysis of Western Red Cedar shake and shingle roofing shipments in North America indicates 12.44 percent of shakes and shingles were pressure-treated to be fire retardant in 2002, according to Ferndale, Wash.-based CHEMCO, the leading treater of fire-retardant exterior wood roofing. 2002 market share was up more than 2.3 percent from 10.12 percent the previous year. Pressure-impregnated cedar shakes and shingles have been demonstrated by independent laboratory testing to pass the same comprehensive fire-safety tests as other roofing materials.

Among factors contributing to the 2002 increase are consumer concerns about fire safety, resulting in increased awareness that fire-retardant wood roofing exists, according to CHEMCO's director of marketing, George Woods.

With a multi-year drought affecting much of the West, and more homes and businesses sitting in urban/wildland interface zones, the potential for significant fire loss is ongoing. On January 9th, the NOAA Climate Prediction Center reported drought conditions remain throughout sections of the interior West and Great Plains. The NOAA report singled out Montana, Wyoming, Utah, Nevada, Arizona and New Mexico as particularly hard hit, while Colorado, North and South Dakota, Nebraska, Missouri and Kansas have seen very little drought relief.

"When homeowners become more concerned with fire safety they seek out information. More consumers are finding us on the web or through our distributors, and CHEMCO becomes their solution," Woods said.

He also cited progress in educating communities with high fire safety concerns. Some have mandated roofing systems be rated Class A, the highest fire-retardant rating. Being unaware that a Class A cedar roofing system exists, a few explicitly ban wood roofing. CHEMCO continues to provide decision makers information about Class A shake roofs.

"That's what happened with San Luis Obispo, Calif., and in November 2002 the city approved Class A wood roofing," said Woods. "We continue to reach out and work with the handful of communities that have not recognized the safety afforded by Class A wood roofing," he said.

"The prestige and beauty of natural cedar roofing is absolutely clear to a significant percentage of higher-end homeowners and businesses targeting a natural look," said Woods. "What we are trying to get everyone to understand is that when pressure-impregnated with an effective fire-retardant formula, wood is also safe," he said.

Real-world Experience

Real-world experience underscores this message. When an Oceanside, Calif. home with untreated wood shingle roofing erupted in flames December 28, 2001, Robert Wueste's adjacent home with CHEMCO-treated wood shingle roofing survived. Merely six feet separated the two structures. Eyewitness statements reported flames were shooting 30-40 feet above the untreated wood roofing.

The fire-retardant wood roofing simply refused to spread the flame. The Vancouver, Wash.-based Western Wood Preservers Institute (WWPI) explains how that is possible. A fire-retardant formula pressure-infused into wood reacts in high heat to neutralize combustible tars and gases that normally feed a fire. Chemical reactions convert combustible tars into carbon char and dilute combustible gases with water vapor and carbon dioxide. The buildup of carbon char on the treated wood also acts as thermal insulation.

When Wueste awoke sometime after 3:30 AM and police carried his wheelchair-bound wife from a smokey bedroom outside to safety, he thought his home and possessions would be destroyed. Not so. The fire-retardant wood resisted the inferno, allowing firefighters enough time to successfully control the fire.

"The fire was so hot it melted the buttons off my microwave sitting about six feet inside the exterior wall, but my home was saved, and I'm thrilled," Wueste said.

San Marcos, Calif.-based Schott Roofing replaced approximately one-third of Wueste's roof, which was black due to carbon char, and items damaged by heat, such as the rain gutters.

The result is that during 2002 the destroyed home was rebuilt with CHEMCO-treated wood roofing, and three nearby homes replaced untreated wood with fire retardant CHEMCO-treated wood shingle roofing.

Fire Retardant Testing For Shakes & Shingles

CHEMCO-treated shakes and shingles are certified for use in Class A, B, and C roofing systems. To achieve a Class A, B, or C rating a fire-retardant wood roofing system must pass nine demanding tests. Moreover, roofing test decks are comprehensively tested, artificially weathered and retested, naturally weathered and tested once more. Among the tests specified by the International Conference of Building Officials (ICBO) are the following.

Spread of Flame Test: Applies a 1400F flame with 12 MPH winds for 10 minutes to ensure no lateral spread of flame on the test roof deck.

Intermittent Flame Test: Applies a 1400F flame with 12 MPH winds for up to 15 two-minute cycles. Simulating the ebb and flow of fire, this proves no exposure occurs due to breaking, sliding, cracking, or warping, and no flying brands are produced.

Burning Brand Test: Blocks of wood are ignited and placed on the most vulnerable locations of the decks. Burning brands must fully extinguish without burning through or igniting the roof deck. Class A tests use a 12-inch brand. Class B tests use two six-inch brands. Class C tests use 20 1.5-inch brands.

Accelerated Weathering Test: About 1.6 million gallons of water are applied over 252 8-hour cycles -- 4-hours of water then 4-hours of drying. Sunlamps heat drying temperatures up to 155F. After 12 weeks, fire tests are repeated to the same standards.

Natural Weathering Test: 15 test decks are placed outside. After one, two, three, five, and ten years of actual weathering, the roof decks must pass the Intermittent Flame, Burning Brand, and Flying Brand tests conducted to the original standards.

CHEMCO was among the first to utilize a unique pressure treating process for Western Red Cedar shakes and shingles, and is the only company to complete the stringent 10-year UBC Weathering Test, based on Underwriters Laboratories' strict standards (UL 790). The test is designed to determine whether treated shakes and shingles hold their fire-retardant qualities when subjected to long-term natural weather conditions. CHEMCO is the only fire-retardant treatment company processing wood roofing that complies with California Health and Safety Code and is listed by the California State Fire Marshal. The continuous evaluation process described above enables CHEMCO-treated shakes and shingles to demonstrate their fire-retardant effectiveness and their acceptance under building codes.

Cedar shakes and shingles treated by CHEMCO are placed in a high-pressure vacuum chamber where air and moisture are withdrawn from the wood. The chamber is then flooded with a fire-retardant formula and pressurized to 150 PSI. The pressure is maintained anywhere from 10 minutes to several hours, depending on the wood's thickness and moisture content. Upon completion of impregnation in the vacuum chamber, the wood is cured in a dry kiln at temperatures up to 180F for three to seven days. Shakes and shingles are then packaged for shipment.

For information regarding building codes and regulations in your area, please contact your local code official.


Supplemental Information

"Focus on Pressure Treated Fire Retardant Wood Products", March 2002, Western Wood Preservers Institute, [Download PDF]

"Fire Tests for Pressure Fire Retardant Treated Wood", March 2002, Western Wood Preservers Institute, [Download PDF]

"Mature El Ni–o Conditions In Place, NOAA Forecasters Report", January 9, 2003, [Read article]

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