NBC4 Fails to Highlight Important Facts Provided in Advance, Airs Irresponsible Story

On November 21, 2016, Washington, DC’s NBC4 aired a flawed report on vinyl siding and fire safety that withheld a number of critical facts provided in advance to the segment’s reporter, Tisha Thompson. Despite efforts by the Vinyl Siding Institute (VSI) to equip NBC4 with a balanced perspective on the issue prior to the broadcast, much of the information was downplayed or ignored, resulting in an irresponsible news segment that deceived viewers about a proven, trusted and affordable material that millions of Americans have used for decades.  

Specifically, VSI’s Jeffrey Smith provided Ms. Thompson a series of facts on October 25, 2016 contesting a number of preconceived misperceptions about vinyl siding and residential fires, including a widely discredited UL study at the center of NBC4’s report. A full copy of Mr. Smith’s letter may be viewed here. Among the facts Ms. Thompson failed to include or clarify in her story:

  • NBC4 sensationalized an 8-year old tragic house fire by laying blame on vinyl siding.  A 210-page report issued by the local fire chief found that a number of factors were to blame for the tragic results of the fire.  NBC4 concealed this critical fact for viewers, and opted instead to show footage of the burning home while misleading viewers to believe vinyl siding may have been the cause – a flawed assumption not supported by the report or other studies. Additionally, NBC4 conveyed the impression that the fire occurred recently, when in fact it took place back in 2008.  Simply put, NBC4 sensationalized a single fire event from eight years ago to create reckless fear and unnecessary concern over vinyl siding safety.
  • UL ignored its own advisory group’s concerns about the study featured in Ms. Thompson’s report. Before undertaking their study, UL convened an advisory group of industry experts, which expressed many concerns about the test plan and tone of the proposed work. UL dismissed those concerns and did not consult with the group through the rest of the program. As a result, the report published by UL reflects flawed test methodology and inappropriate conclusions.
  • Members of the advisory group have publicly disputed the UL report. The UL report and associated video modules – which suggested that construction using wood sheathing provides a significant advantage over other sheathings – are misleading due to flawed methodology. The UL tests used an unusually high-energy ignition source and atypical plywood sheathing, rather than the more common OSB sheathing. UL performed improperly controlled tests that mischaracterize the role of vinyl siding in house fires. When properly controlled tests are done, the differences between the use of plastics and wood are less significant or non-existent. 
  • UL has not responded to these concerns and continues to make it available online. The technical deficiencies in the UL report were so egregious that representatives of UL’s working group signed a joint letter in February, 2016 urging UL to promptly remove the report and related wall assembly training videos from UL’s website, UL’s YouTube channel and other UL forums to avoid misleading the public. UL dismissed the working group’s request to have the flawed study taken down.  Remarkably, UL never even responded to the facts presented by the working group regarding the discredited report.
  • No residential exterior cladding is designed to be a barrier to fire. NBC4 conveyed the impression that vinyl siding should act as a fire barrier to underlying insulation, but that is not the intended role of vinyl siding, wood or any residential exterior cladding. Viewers are right to wonder why NBC4 would selectively hold vinyl siding to this high standard – and fail to point out that wood exterior cladding would likely ignite and burn before the vinyl siding, and likely before any underlying material that the vinyl siding might expose. Moreover, wood sheathing is one of the materials that may be found underneath siding, but such material is already exposed when the house is clad with wood.
  • The story improperly suggests that vinyl siding is specifically responsible for spread of fire. Typical houses are by design composed primarily of combustible materials. Combustible sheathings of several types are normally used under the cladding. When a wall catches fire all of the combustible materials will contribute in some way to fire progression.  Because of its inherently fire retardant characteristics, vinyl siding is neither the only nor the primary cause of fire spread. Indeed, when a noncombustible material is used, a fire involving just vinyl siding is far less aggressive and may not even progress all the way up the wall.
  • Vinyl siding is more difficult than many other building materials to ignite. Vinyl, also known as PVC or polyvinyl chloride, starts with two simple building blocks: chlorine (57%) from common salt and ethylene (43%) from natural gas. This means vinyl siding won’t ignite, even from another flame, until it reaches about 730°F (387°C), and will not self-ignite until 850°F (454°C). Those ignition temperatures are significantly higher than common framing lumber and wood exterior wall covering, which ignites from a flame at 500°F (260°C) and self-ignites at 770°F (410°C).
  • Even if ignited, vinyl siding burns more slowly than wood. Tests show that vinyl siding needs unusually high amounts of oxygen to burn and stay burning. It will not independently sustain combustion in air with a normal concentration of oxygen (about 21 percent) — so it extinguishes relatively easily.  A more detailed explanation of this may be found here.

The fact is, residential fires rarely start outside the structure, and claddings of any type are seldom a factor.  According to the National Fire Protection Association, only four percent of all residential fires start on the outside of the structure, but do not necessarily originate with the exterior cladding. Fewer than two percent of house fires originate with the exterior wall surface, and fewer than three percent of all fires go beyond the structure of origin. The most common areas that produce fires are the kitchen, bedroom, and living room, and most fires (69 percent) never leave the room of origin.

To contain residential fires, efforts should focus on limiting the spread of fire to critical areas. This includes eave construction, for example, which should be reexamined to slow a fire’s acceleration from the exterior wall to the attic.  One approach would be to “harden” the interface between the exterior wall and the attic so that fire cannot spread so readily into the attic. This would be consistent with the overall fire protection strategy for combustible buildings, which is to compartmentalize fire so that it cannot readily spread to different areas of the building, while still providing necessary functions such as ventilation. 

We thank our brave firefighters for their courageous service to our country. But their concerns with respect to vinyl siding and home fires are misplaced. VSI will continue to work closely with Chief Brower, other fire service members, and other material stakeholders to study recent trends in suburban fires. Our focus has been on working cooperatively to identify appropriate actions that can be taken to accurately and effectively address correctable fire safety issues, and ways to limit fire spread into the building interior.  

Below are the complete, unedited interview segments of VSI’s spokesperson, Kate Offringa, clarifying a number of facts about vinyl siding and fire safety, many of which were missing from NBC4’s report: