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  • Writer's pictureLaurie Fisher

What Are "Construction Types"?

The building codes (International Building Code and California Building Code) categorize building methods and materials into five “types”, according to degrees of combustibility. Type I is the most fire-resistant and non-combustible, whereas Type V is the least fire-resistant and allows combustible materials.

Amazingly, even in the face of tragic wildfires, California homes, and the vast majority of homes in the US, are still built as Type V, with highly combustible wood beams and studs. In comparison, the load bearing walls in a PHNX Home are Insulated Concrete Forms (ICF) - non-combustible, 4-hour fire rated walls. PHNX Homes are ICF homes.

Occasionally we will see homes and housing built with light-gauge steel framing; however, this is still considered Type V construction, as steel framing nonetheless requires combustible wood sheathing for walls, floors and roof. Light gauge steel will also deform if exposed for the extended periods of time at very high temperatures we see in wildfires.

The raison d’être for building codes all over the world has always been to protect people from burning buildings; life safety comes first and structure a distant second. And fire life safety codes were developed from the perspective of buildings burning from the inside out, not from the outside in as they are in wildfires!

In order to give people inside a burning building time to get out safely, the code devised “fire-rated assemblies” for floors, walls, and roofs. You may have heard people speak of one-hour, two-hour, or even four-hour ratings; this establishes the length of time before an assembly will ignite and fail.

While the longer ratings are intended to keep the main structure mostly intact until fire fighters can get to the scene, two- and four-hour rated assemblies are never required in typical single family homes. Since the code prioritizes getting people out while the structure burns from within, those long-hour rated assemblies simply aren’t necessary in a smaller structure with few occupants. We don’t even see them as an option, as two- and four-hour assemblies get quite expensive to build in Type V construction. Besides, even with the longer assemblies, your home will still burn after four hours.

The California Building Code responded to the wildfire danger with the adoption of international Wildland Urban Interface requirements in the 2011 CBC update, making automatic fire sprinklers mandatory in all single family homes and requiring “non-combustible” exterior details. Obviously, since homes are still built mainly of wood, these requirements are not truly “non-combustible” - they merely provide a “one-hour protection” at vulnerable areas of a structure. After one hour, that assembly will likely ignite.

Our PHNX Home is non-combustible. Built of concrete and steel, a PHNX Home contains no structural wood. It is not a highly combustible Type V structure; a PHNX Home is a Type I-A structure - the most fire resistant, non-combustible construction possible by code. Your new PHNX ICF Home may suffer some minor cosmetic damage in a raging wildfire, but its structural integrity will remain intact.

Since a PHNX Home will not burn, it won’t ignite your neighbor’s home. It will not propagate a wildfire; instead, it can actually help to stop it. A cluster of PHNX ICF Homes could even serve as a fire break.

While no one can predict to what extremes our new and rapidly changing environment will take us, we have already seen Insulated Concrete Form homes survive some of our most deadly fires. Your belongings will be protected, and you will have a home to come back to.

Contact us today and find out how our PHNX Home can become your Forever Home!

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