In this article, we won’t focus on the causes of the fires in LA and their increasing magnitude since that is covered in depth elsewhere. In short, however, policies of total fire-suppression disrupt the natural burning cycle of ecosystems allowing tinder to build up and the fires that occur spread more rapidly and burn with greater intensity. Proper maintenance of brush-clearing is labor-intensive, difficult to enforce, and not pragmatic in most cases. Instead, we will discuss the best practices that can be realistically undertaken to lessen the impact of future fires. 

Due to population pressure in California, and mass-suburbanization, more neighborhoods are within the Wildlife Interface Zone than ever before. Reducing the number of dwellings in proximity to the hills and wildlife is not politically realistic or fair, especially given that the City of LA is struggling to provide sufficient housing in its urban areas as it is.

The history of fires in the US provides precedent for how governments and organizations responded to fires. In 1886, the insurance industry organized a trade association, the National Board of Fire Underwriters, after the Chicago fire. In 1893, Underwriters Laboratories (UL) was founded, providing a metric for many fire construction assemblies (1). Today, UL serves as the testing authority on fire-rated assemblies. 

The City of LA has a mechanism for more stringent fire code in areas designated as Very High Fire Hazard Severity Zones (VHFHSZ). Most of the hillside areas fall under this designation. Today, however, the code is rather lenient and only requires incremental measures over standard construction. Houses are built like they usually are, out of wood studs and plywood, with a few differences. 

Generally speaking, increasing the distance between dwellings can assist in preventing the spread of wildfires. Given how tight the lots are, and the fact that it is not presently possible to mandate that owners build back smaller, it is likely impossible to require larger setbacks and distances between fires, although this has the potential to slow the spread of fire. What can be done in these zones, however, is to require a 1-hour fire rated wall on the exterior of new construction. After all, today, a 1-hour rating is required for walls that are less than 5 ft away from a property line. A 1-hour fire rated wall is easily achieved with stucco and type-X sheetrock/gypsum board on the inside. Stucco and gypsum are both fire-resistive materials due to their cementitious and mineral nature; they are non-combustible. 

Overview of current requirements in fire areas within the City of LA 

Today, VHFHSZ (AB38) requires three main items. Though stucco walls provide good fire-resistive properties, if the eaves catch fire, the whole attic goes up in flames, where fire can spread very quickly. Similarly, the raised floor provides a similar opportunity for fire. In hillside areas, fire can obviously spread under houses perched over hillsides. Due to this, the current code requires either there to be no exposed under-floor areas, or all overhangs and floors that are exposed to have 1-hour rated, with no exposed utilities. For obvious reasons, furnaces, and other mechanical equipment, which used to be predominantly natural-gas-fired, is required to be shielded with 1-hour fire resistive walls. Current codes also require attic openings to have  ¼” non-combustible corrosion-resistant screens to prevent embers from entering the attic spaces. All roofing needs to be class-A fire resistive.

Codes do not differentiate between asphaltic shingles, metal, concrete, and clay roofs. All achieve a Class-A rating. I believe this is misleading, since at high temperatures, bituminous roofs will light up if exposed to temperatures high enough and for lengthy periods of time. Shingles made from asphalt are not an optimal solution for high fire risk areas. Instead, metal roofs with a fire-resistive underlayment such as DensDeck, VersaSheild achieve a class-A fire rating using non-combustible materials, helping prevent heat conductance through the metal. Clay tile similarly achieves a class-A rating. 

Opportunity for exploring new ways of building

Rebuilding gives us the opportunity to move away from wood stud-frame construction and motivates homeowners, designers, and builders to explore alternatives. 

Non-combustible methods include:

  • Type 5A construction

    This method is when you take the conventional wood-framed building, yet you wrap the floor, roof and wall assembly with Type X Gypsum Board and stucco, as an example, on the exterior. While this will eventually catch fire and add fuel to the fire, this is a considerable improvement over most houses.
  • Light-gauge steel stud

    This is perhaps the simplest and most-common method of building using non-combustible materials. Instead of wood studs, light-gauge steel is used. The steel is cold rolled into profiles. The assembly is then covered with drywall from the inside and structural sheathing on the outside, providing the required strength against earthquakes. Non-combustible sheathing products can be selected. Steel frames are often used in conjunction with this construction technique.
  • Tilt-up construction

    This is where concrete walls are poured on-site and hauled up. Numerous architects explored this technique in the early 1900s in Los Angeles, including Irving Gil and Shindler
  • Block (concrete masonry)

    Cementitious block is an accessible way of building with concrete without having to erect formwork since the blocks can be placed by a mason, and while heavy, they do not require machinery to place. 
  • Concrete cast-in-place 

    Cast-in-place concrete is a labor-intensive process, yet it allows for stunning aesthetics if poured well and if the form is designed with care. The labor involved is what makes this method of building particularly expensive. 
  • Reinforced adobe

    Adobe block construction uses stabilized earth that is capped on the bottom with the foundation and on the top with a bond-beam which is cinched down using post-tensioned rods. 
  • Rammed earth

    This method of building is most similar to concrete, yet instead of using aggregates sourced from afar, a qualified builder mixes the aggregates that exist in the soil on site and import a smaller quantity to make sure the mix is well-graded. This is then mixed with cement and water in order to achieve similar compressive properties as concrete. 

Marginal changes that can be made today 

Fire life-safety is presently organized through a series of construction types. Buildings are put in broad categories, ranging from Type 5B (the least fire resistive) to Type 1A (the most fire resistive). Houses are usually built according to Type 5B, whereas skyscrapers are typically Type 1A. An easy switch is to require Type 5A – a slight improvement, still within the Type 5 category, for homes within fire zones. We can easily move from 5B to 5A. This requires using fire-rated construction for all bearing walls and floors. This is readily achievable, it simply requires using a different type of gypsum board on the inside, protecting the roof (vaulting the ceiling, for instance), and using stucco or another fire-resistive assembly for the exterior walls. Type 5A requires the structure of a building to be protected. This will likely slow the spread of fire. 

Alternatively, if we want to take things further, homeowners could be encouraged to use Type 2 construction. Type 2 is when the materials used for construction are non-combustible in nature. Think concrete, metal studs, and gypsum board, and DensGlass on the exterior of a home. Many luxury homes are built this way today due to economies of scale when it comes to metal framing and requirements for straighter walls. Of course, this is more expensive. However, metal stud construction is sometimes comparable in cost, and the increase is not an order of magnitude. 

New homes are already required to have fire suppression systems. Homeowners could be incentivized to use active fire suppression systems such as Front-line Fire Defense on the exterior of their homes, yet these active systems require maintenance and vigilance on the part of the homeowner. Already, sprinklered construction is required for new dwellings, but, during mass fires, sprinklers begin to drain the available water from fire hydrants, contributing to a shortage of water pressure for fire crews. 

-Kirill Volchinskiy, AIA 

For any questions or comments, please feel free to reach out: projects@oca.la

1 – Bloomberg https://www.bloomberg.com/news/features/2025-01-17/the-los-angeles-wildfires-should-change-the-way-we-live

2 – Longreads https://longreads.com/2018/12/04/the-case-for-letting-malibu-burn/