Mammoth Fire Department effort to head off wood burning hazard lengthy, costly
Pictured: Heller (left) and Goetz with examples of local header board pyrolysis scorching. (Photo: Geisel)/
Inserted wood burning stoves and appliances are common in Mammoth Lakes. In fact, there are probably thousands of the devices installed in buildings built here between the ‘60s and ‘80s. It’s such devices in those buildings that has Mammoth Lakes Fire Protection District on alert, and preparing to launch one of the biggest, and likely controversial, efforts in its town history.
According to Fire Marshal Thom Heller, already in the works is a modification to the Town of Mammoth Lakes code that will, if adopted by Town Council early next year, start the clock running. Buildings, such as condo and townhome complexes, with the devices will have 10 years to correct a serious problem, that could, if not addressed, lead to fires, and loss of property and possibly lives.
During a fire code update meeting last week, Heller said at least eight structure fires in Mammoth during the past 10 years or so have had at least one thing in common: an inserted wood burning appliance installed inside a previously used zero-clearance fireplace box. Investigations of each incident found that wood, plywood or sheetrock behind the rock, brick, metal and/or wooden facades or fascia didn’t meet the required distance for proper installation of the inserts.
Pellet stoves and gas inserts, as well as masonry-built flues and chases, are not the issue, he added.
The newer appliances’ efficiency and BTU output already exceed the specifications for the original fireboxes. As a result, pyrolysis can set in, which is basically scorching or charring that leads to decomposition of the wood or construction materials. Combustible gases and moisture in the materials are slowly burned off, and the ignition temperature gets lower and lower until it finally catches fire.
Thus far, there have been no injuries from the incidents, though Heller pointed out that losses and constructions costs to the mostly residential/multifamily structures (and one single-family home) have been significant. One Mammoth complex had two fires related to insert problems, and upon inspection, 23 of the 60 units showed various signs of heat damage to combustibles.
Background
As a result of the Arab oil embargo that began in 1974, according to MLFPD there was an uptick in the installation of wood burning stoves and inserts, especially for residential heating. Wood burning in Mammoth had been a traditional source of home heating, but mostly in fireplaces. With open fireplaces causing air quality issues, new air standards were enacted in the ‘80s, leading to an even wider use of inserts.
Inserts are a variation on wood stoves, initially designed, tested and listed by Underwriters Laboratory for insertion in masonry fireplaces. They were, MLFPD says, originally not intended for use with factory built fireboxes or anything other than masonry. With sales on the rise, installers quickly jumped on the bandwagon, and put the stoves in factory fireboxes, though the stoves never underwent UL testing or listing.
Manufacturers, cranking out the inserts hand over fist, had their products tested to UL “standards,” that Heller said is not the same as getting them “listed” by UL itself, which is used as a basis for developing fire codes. The manufacturers, he submitted, did not have the stoves tested in zero-clearance fireplace assemblies.
Igniting controversy
Heller and others involved in drafting the new code changes say they’re well aware of the impact on the community. With potentially thousands of such inserts in use, it won’t be quick and making the corrections won’t be cheap. Most if not all inserts installed prior to 2010 will have to be removed and reconstructed upon sale, or by Oct. 31, 2022, if no sale has occurred.
So far, the recommendation that will be submitted to Council for its deliberation calls for a minimum of 48 vertical inches of non-combustible material within the chase, measured from the top of the existing prefabricated metal firebox. A minimum of 24 horizontal inches of non-combustible material shall be installed within the chase, measured from the edge of the wood-burning insert. And if manufacturer’s specifications require more, those will take precedence.
“The distances between provide dimensions the manufacturers don’t provide in their basic instructions,” Heller said.
Heller said he and Town Senior Building Inspector Johnny Goetz have had “multiple meetings” with contractors to develop a working draft of specifications and a list of approved insert manufacturers for the new code changes.
“We’ve also consulted with the top agencies and experts in the country, including UL,” Heller noted.
Town Attorney Andrew Morris said the draft thus far is enforceable as an ordinance.
That enforcement, Goetz thinks, has to start with public buy-in.
“The only way to enforce this is to get people on board and with education,” Goetz said. “Realtors, contractors, the lodging community, the Chamber [of Commerce], Homeowners Associations all need to understand the magnitude of the problem. There are probably thousands of these in town, and we’ve already had eight fires, which is eight too many.”
Heller added that testing of header boards pulled from already converted buildings in town indicated more fires could be in the offing. One expert he cited suggested that, where Mammoth has been averaging about one to two fires per year, the town could expect possibly 4-5 per year on average.
“Renters have fires for ambiance, but also for heat,” Heller said. “They leave the stove doors open and efficiency goes out the window, but they just throw more wood in, which drives up the temperatures. They also used a lot of compressed logs, which burn three times faster and hotter than wood.”
“It gets down to a money issue. The reality is this thing’s going to cost a lot of money,” Mammoth contractor Greg Jennison said. “Get ready now, start saving … 10 years will be here before you know it.”
Jennison posited that the cost involved depends on the type of fascia involved and whether or not remodeling is an option for the insert’s new appearance, but estimated it could run at least $3,000-$5,000 to as much as $10,000 per unit. Local equipment vendor Alpine Stove concurred with those figures.
Citing a recent fire on Old Mammoth Road, that was linked to an insert issue, in which fatalities were narrowly avoided, Jennison said, “It doesn’t get much closer than that.” Heller said his hope is that owners will “redo the whole thing,” and bring the entire complex’s inserts up to code.
“Our challenge, though, will be to keep this in front of as many organizations and stakeholders as possible during the next 10 years.”
Also being looked into is help in the form of possible equipment rebates, and subsidies or steep cost breaks for low-income or income-challenged residents.
“On first look, you’d think the fires were attributable to bad installation,” according to Richard Good, a former contractor, who now sits on the Fire Department’s Board and on the Contractor Board of Appeals. “Even with new inserts, though, the header boards could have been charring from years earlier. In the ‘60s and ‘70s, we didn’t know as much and these inserts have evolved in efficiency and heat output since those days.”
Heller pointed out that in much of the Midwest and the East Coast regions of the U.S., most fireplaces are all stone and masonry. On the West Coast, though, we aren’t the only locality dealing with this problem. Orange County, for example, has been dealing with plywood used in decorative fashion to conceal stovepipe tops, which have been showing signs of pyrolysis.
Wood burning inserts from 2010 on are up to the new proposed standards and likely won’t need to be addressed, Heller said. Locally, Mammoth Creek is 100 percent up to date, and San Sierra is at or near completion, while 1849 Condos are in the early stages and Chamonix is negotiating with its HOA. But that, he added, still leaves a long way to go.
“This could be the hardest thing I’ve ever done here,” Heller stated.
The Contractor Board of Appeals is set to take up the draft ordinance language and related matters during its next meeting on Nov. 7. Council is expected to review the proposed code language sometime in January 2013.
