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3 common vinyl siding myths dispelled

Vinyl siding is fire-resistant and carefully regulated


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3 common vinyl siding myths dispelled

Vinyl Siding Institute

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The following is paid content sponsored by the Vinyl Siding Institute

By FireRescue1 BrandFocus Staff

You may be aware that vinyl siding is the most common choice for exterior cladding in residential homes in the United States and Canada, listed by the US Census Bureau as the most common such material in the country.

A house with vinyl siding (Photo Credit: ntm1909 via Compfight cc)
A house with vinyl siding (Photo Credit: ntm1909 via Compfight cc)

But as a firefighter, you may think that vinyl siding has a dark side – that it contributes to a great many residential fires, and that it is not covered in building codes.  

The truth is that vinyl siding is a safe material on residential buildings and has been recognized by the building codes for years. Here are three common myths regarding vinyl siding, and the reality.  

Myth: Vinyl siding burns easily

Reality: Vinyl siding is harder to ignite and easier to extinguish

While all organic materials (that is, anything containing carbon) will ignite if exposed to a high enough temperature, vinyl siding is more difficult than many other building materials to ignite because it is composed mainly of polyvinyl chloride, more commonly known as PVC, which is inherently flame retardant due to its chlorine base.

This means PVC won’t ignite, even from another flame, until it reaches about 730°F (387°C), and won’t self-ignite until 850°F (454°C). Those ignition temperatures are significantly higher than common framing lumber, which ignites from a flame at 500°F (260°C) and self-ignites at 770°F (410°C).

In addition, results from the ASTM E162 test show that PVC has one of the lowest flame spread ratings of the materials tested, meaning that it won’t typically contribute to the spread of fire.

Finally, ASTM D2863 tests show that rigid PVC’s high Limiting Oxygen Index means that it needs unusually high amounts of oxygen to burn and stay burning. Rigid PVC (vinyl siding) will not independently sustain combustion in air with a normal concentration of oxygen (about 21 percent) — so it extinguishes relatively easily.

Myth: Vinyl siding is a contributing factor in many fires

Reality: Vinyl siding is not a contributing factor in the vast majority of residential fires

In fact, claddings of any type are rarely a factor in residential fires. According to the National Fire Protection Association, only 4 percent of all residential fires start on the outside of the structure, but do not necessarily originate with the exterior cladding; fewer than 2 percent of house fires originate with the exterior wall surface; and fewer than 3 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.

Myth: Vinyl siding isn’t covered in building codes

Reality: Vinyl siding is regulated for building safety

The 2015 International Building Code allows vinyl siding to be a part of a prescriptive fire rated assembly approach because vinyl siding does not contribute to the growth of a fire.

Building codes established by the International Code Council require vinyl siding, polypropylene siding, and insulated vinyl siding to be certified and labeled by an approved quality-control agency to show they conform to their respective ASTM standards. Federal, state and local building code entities throughout the United States adopt the ICC model codes.

Due to its fire-retardant properties, vinyl siding is approved by Underwriter Laboratories in a wide variety of fire-resistive wall assemblies. It is one of the few materials that meet the National Fire Protection Agency requirements for insulating electrical and data transmissions.

In fact, PVC first came into popular use as a fire-safe means of insulating residential wiring. Millions of homes across the country have been using safe, vinyl-sheathed wiring for years.

It can be used in all types (1-5) of construction, including non-combustible rated structures up to 40 feet in height, one-hour rated fire assemblies and other fire resistive construction.

While there may be some bad publicity surrounding vinyl siding, the evidence shows that it is a safe cladding material. It is inherently flame retardant due to its unique chemical makeup, rarely a contributor to home structure fires, and well represented in building codes. 

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