It appears that California’s wildfires aren't about to slow down their assault anytime soon. Indeed, thanks to climate change, the state’s annual burned area has undergone a fivefold increase between 1972 and 2018.
Spurred by the surging rate of fires and Californians' reluctance to stay away from the burning wildlands, builders, architects, and homeowners have had to adapt. Building materials, home designs, and the very norms of aesthetics have undergone a drastic shift.
Traditionally, building codes and fire departments have focused on prohibiting or reducing flammable components in structures. Over time, substitutes for traditional building materials evolved to offer visually appealing options. Meanwhile, homeowners slowly accepted steel, concrete, and stone as the safer alternative to wood, glass, and vinyl. In like manner, the use of hard landscaping and fire-resistant brush is emerging as a viable defensible space strategy in California's idyllic mountainside areas.
Fire Resistant Home Construction
Fires need oxygen and fuel to burn. Oxygen may be removed from the equation, often too late, with mechanical suppression systems, such as sprinklers. Removing fuel from a fire's path means using non-combustible materials on a building's exterior. To work effectively, all the envelope components should be fire-resistant, as the exterior is only as strong as its weakest link.
A key objective of a fire-resistant exterior is to keep flames away from the fuel-laden interior of a building. In this regard, windows and skylights are the chinks in the armor, and upgrading these components to meet the threat of wildfires should be a priority.
Not all glass is created equal. Single-pane glass doesn't perform well when subjected to heat and should not be used in fire-resistant construction, nor should plastic skylights. Instead, consider heavy-duty glazing, such as SaftiFirst's SuperSecure II-XLS 45-120. It is rated up to 120 minutes and comes in sections as large as 8' X 8' with flame-resistant gaskets and calcium silicate setting blocks.
It's equally vital that you take the fire-resistance of doors into account. The choice of material is important, but doors have other vulnerabilities that must be addressed to achieve an acceptable level of fire safety. For instance, embers can easily slide under the door or become trapped in the openings of the frame. Further, door glazing is more susceptible to failure than the door slab itself and should be rated like any other exterior glazing component. Steel doors with proper weather stripping, door sweeps, and no glass are the most dependable option.
Siding comprises the most considerable portion of a home's exterior walls and thus has significant exposure to advancing flames. Luckily, there are plenty of non-combustible siding materials. In fact, it's easier to name those you should stay away from altogether: wood and vinyl.
Conversely, your best options for fire-resistance are fiber cement, steel, and masonry veneers that don't leave any nooks or crannies in which embers can get lodged. With a bit of creativity, you can use these while sparing your structure from a nuclear bunker look.
As wildfires move across a property, they have a good chance of coming in contact with the roof or at least attack it with flying embers. Protect your roof by choosing a non-combustible material, and avoiding crevices where embers or burning debris can get stuck.
Metal roofing comes with the options of steel, zinc, copper, and various alloys. It provides a great barrier to wildfires, and when installed in sheets rather than wood or asphalt shingles. It's also effective at preventing burning debris from getting lodged. Metal roofing is surprisingly versatile in appearance and can be fashioned to resemble organic materials, such as wood, clay, or stone.
Concrete, clay, and slate tiles are fire-resistant by nature. That said, they have to be installed with the embers in mind; what use is a non-combustible roof if burning twigs can make their way through their cracks? Another factor to keep in mind is the added weight of these materials. Given their loads, the roofing structure requires adequate reinforcements.
Synthetic roofing materials score high on fire-resistance, and thanks to their light weight, they don't require additional structural considerations. This type of roofing typically comprises shingles made of virgin or recycled rubber, combined with recycled plastic. These synthetic shingles offer a wide array of styles and sizes, while providing a seamless surface free of crevices. Since they’re easily recycled at the end of their lifecycle, synthetic roofing materials are also considered “green”.
The methods listed above offer a significant degree of protection against fires. That said, relying on non-combustible materials implies allowing the fire to attack the structure in the first place.
Yes, certain materials will not combust in a fire; but, many may still fail when exposed to heat, especially over a long period of time. Glass breaks, metal melts, concrete expands, falls apart, and can even explode. If your building relies solely on non-combustible exterior materials, there's a good chance the fire may sneak indoors when one of these materials succumbs to extreme heat. Now, unless your interior is likewise built with non-combustible components, it will be the next source of fuel for the raging flames.
So, while sprinklers and non-combustible materials are valid strategies (and, in many jurisdictions, the law), relying only on these two methods is not enough to prevent fire damage. With this in mind, architects and designers have been striving to stop wildfires from coming in contact with a building altogether. With such a shift of mentality, the focus moves from building fire-resistant homes to creating fire-resistant properties.
If you or your client have the flexibility to choose a site before building, you're at an obvious advantage over those who don't. Staying away from fire-hazard areas is the most effective fire protection strategy you can ever pursue. As experience shows, it's not for everyone – despite the alarming rise in wildfire occurrences, Californians continue flocking to the fire-prone wildlands in equally increasing numbers. So, how can builders protect their homes in these dangerous areas?
Consider the topography
Large swathes of California's wildland areas are spread out over hills, cliffs, and generally uneven terrain. The astonishing scenery is partly what makes this land, and hillside lots, so desirable to aspiring homeowners.
Unfortunately, hillside properties face a disadvantage when it comes to fire resistance. In most cases, fires move faster uphill than they do downhill or over a flat surface. If you have a hillside structure in a fire hazard area, take this risk into account. Build on even terrain where possible; otherwise, make sure the property has a fire barrier, such as a wall or a driveway between the building and the downslope.
Deny wildfires access to fuel
Wildfires may spread slower over a flat surface, but, driven by wind, they still move and burn any fuel in their path. Grass, shrubs, trees, and dry organic matter, in general, are an excellent fuel source, as are the obvious items, like propane tanks, paint, and other chemicals.
Hard landscaping and fire-resistant plants are a relatively new yet booming trend in fire hazard areas. Over time, these elements have been perfected to offer a versatile aesthetic to suit any homeowner's fancy. Consider creating a "defensible space" around the building with non-flammable vegetation and a combination of driveways, as well as concrete or stone pavers and walkways.
Design Everest can help
Whether you or your client are rebuilding or erecting a new structure in a fire hazard area, our engineers can help. Design Everest has served California for over 14 years, and our team has the expertise you need to make your project successful. We offer a full suite of services, including structural, civil, mechanical, electrical, and plumbing design. What's more, we provide architectural drafting, 3D modeling, and rendering support to architects. Contact us at (877) 892-0292 to discuss your project and receive a quote today.
*Note: The content published above was made in collaboration with members of Design Everest.
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