Four Strategies for Protecting Your Home Against Wildfire

When Designing and Building a New Home in California, There Are a Number of Things You Can Do to Protect It from Wildfires

Is “Fire Season” part of our “new normal” in California? Ten to 20 years ago, wildfires were primarily limited to summer months. In recent years, fires have raged across the state through fall and winter, fueled by the dry conditions of drought and record temperatures.

Headlines reading “Megadrought worsens to driest in at least 1200 years” announce research confirming that 20+ years of drought – known as the Megadrought – in the western U.S., worsened in 2021, making it the driest in at least 1,200 years.

That news comes as no surprise to California residents – at least not to me.

There is no doubt of the direct link between drought, heat, and the wildfires devastating the West for years. In 2021 alone, 8,619 fires burned more than 2.5 million acres across California.

These are frightening times to be sure. With so much uncertainty in the air (literally), how can one begin to manage the new risks of living in the West?

There are a number of things one can do to mitigate fire risk when designing and building a new home in California. Some even apply to your existing home. These are the strategies that could save your home and your life. 

That said, it takes a multi-layered approach if you’re to have a fighting chance against Mother Nature’s immense power. 

As an architect designing homes in northern and southern California, I have come to think of it as a Four-Part Strategy: Proximity, Combustibility, Infiltration, and Protection. Follow all four and you’re on your way to protecting yourself, your family, your home, and even your neighbors from the risk of wildfires. 

The following is our strategy:

Proximity

Keep Any Approaching Fire as Far from Your Home as Possible

Location - As the real estate saying goes, it’s all about “location, location, location.” This mantra holds true when it comes to fire resiliency too. Particularly vulnerable are sites located in what’s referred to as the urban/wildland interface – that zone of transition between wilderness and land developed by and for human activity. 

While home sites in the urban/wildland interface can be highly desirable for their combined convenience and natural beauty, these intermingled geographies are especially at risk for catastrophic wildfire. Steering clear of building in these areas is your first and best way of protecting against wildfires. 

Of course, this isn’t an option for everyone, nor might it be everyone’s choice. If you still plan on building within an urban/wildland interface, you must pay special attention to the other aspects of fire resiliency, those aspects that you can manage.

Site - Managing your site is key. This can be done in a number of ways. A “defensible space,” as it’s sometimes called, consists of creating concentric rings of space (three zones) around your home with decreasing levels of combustibility the closer you get to the structure:

Zone 0 – Your home structure and the immediate 5’ around it is identified as an Ember Resistant Zone. The most important of the three zones, the strategy here is to limit the amount and types of vegetation within 5’ of your home. Incidentally, keeping your roof gutters clear of twigs and leaves counts as possibly the most important element of your Zone 0 strategy. 

Zone 1 – Known as the Lean, Clean, and Green Zone, this refers to the space that extends 30’ from the structure. Fire resiliency mandates practices that mirror the name: Keep your vegetation lean, clean, and green. The less there is to burn, the better off you and your home will be. 

Zone 2 – Is called the Reduce Fuel Zone, extending from 30’ to 100’ beyond your structure. Less stringent than the prior two and out of reach for small parcels, this zone is more akin to what you may have heard referred to as “raking the forest.” Regardless of your political views, raking the forest is actually a thing and it can help a lot, especially when it’s about managing the outer reaches of your own property. See CalFire’s website for more information on setting up your own defensible space.

Combustibility

Build Your Home from Materials That Burn Only at Very High Temperatures

Structure. Most homes are built from combustible materials, namely wood. These days that means lots of 2x6 wood studs. Framing your new home with almost anything other than wood can help, but even some noncombustible materials can have problems in very hot fires. 

One option is heavy timber, aka post & beam, construction. These timber are deeper and fatter than a 2x6 and thus act more like mini redwood trees. They can char but won’t burn in the same way that a 2x6 will. That said, you don’t want things to get that bad, going so far as to char. So what other options are there?

For one, metal framing is a viable alternative, either lightweight metal studs or structural steel members. The former can still be susceptible to high-heat fires but insulated properly, can be more resilient than wood studs. Heavier, structural steel shapes (I-beams) are quite fire resistant as compared to wood framing, but these systems can be expensive. There are even some systems that fall in between the two, called medium-gauge framing. These systems can be relatively cost effective, some even coming as a kit of parts that can be assembled on site like Tinker Toys.

Finally, there’s the gold standard of non-combustibility: Concrete. Today, concrete for homes comes in two main forms, cast-in-place concrete and concrete block. Rammed earth, a beautiful but expensive option falls into this “cementitious” category. These are by far the most fire resistive structural elements that one can use to build a home.

Insulation. Wildfires can get very hot (up to 1,500°F), and the hotter they get the more damage they can do. Insulation can help protect your building’s structure from damage. However, many forms of insulation are themselves susceptible to high heat. 

The most common insulation used in homes today, fiberglass batt insulation (usually pink), melts at a little over 200°F. Rigid foam insulation (expanded polystyrene [white], extruded polystyrene [blue or pink], or polyisocyanurate [yellow]) melts at a little less than 300°F. 

Natural wool insulation burns at about 600°F, quite good when compared to other types of insulation. Natural wool is of course a super nontoxic and sustainable solution. But the winner by far is mineral wool (gray colored). Made from spun, molten rock, mineral wool is essentially a ceramic fiber and thus performs quite well under very high heat. It won’t burn until it reaches 1,800°F.

Roofs. Many roof systems are particularly susceptible to burning. Red hot embers from a fire tens of miles away can land on a roof and set dry, combustible roofing materials on fire in moments. This being the case, wood shingles aren’t a great option, that is unless they have been fire treated. Membrane roof systems made from compounded plastics can melt and burn easily and so are not great choices when it comes to fire resilience. Clay tile roofs, while good in concept due to the non-combustibility of the material, often have open-air cavities between the tiles, under which hot embers can enter, setting the layer of roofing under the tiles on fire.

The best options by far, with regard to combustibility, are metal roofs and those made from cementitious planks or panels. These roofing materials, while non-traditional, can be very attractive and go a long way to protecting your home from fire hazard.

Siding + Sheathing. Exterior siding and sheathing materials, the layer under the siding that you see on the outside of the home, mirror those of roofs in many ways. Wood, unless fire treated, can burn easily. Metals (applicable for siding but not sheathing) and cementitious materials resist fire well. As with roofs, the way in which these assemblies are detailed and put together can either strengthen or weaken their fire resistivity. An experienced architect will ensure that these elements are put together in ways that are both effective and attractive.

Infiltration

Prevent Sparks, Embers, and Flames from Reaching the Interior of Your Home at All Cost

Venting. Attic and eave vents are particularly vulnerable to infiltration by sparks and embers. A single spark – sucked into an eave or attic vent via temperature and pressure differentials between inside and out – can get into the unoccupied area of a roof and easily set insulation on fire without anyone even noticing until it’s far too late.

Building code requires roof venting to help heat and moisture escape unoccupied spaces within a roof structure. These vents have traditionally been the Achilles’ heel of fire protection. However there are now new products on the market that allow for venting, yet prevent sparks and embers from infiltrating your roof. Many municipalities now require this new kind of vent. In our opinion, you should use these new types of fire resistant vents on your new or existing home regardless of whether your local code agency requires them or not. This is a very cost effective form of insurance.

Window Protection. Windows are particularly vulnerable aspects of your building. If one breaks allowing sparks, embers, or flames to infiltrate your home, it could easily mean total destruction. One option here is to integrate window protection on the exterior. The most common solution here would be fire resistant shutters. Off-the-shelf solutions are pretty unattractive and difficult to work with across the large window expanses of modern home design. Custom building shutters can be an effective and attractive option. For large areas of glass, we have custom-designed and fabricated fire-resistive barn doors. This approach can add an attractive architectural element to your home while at the same time providing protection from fire.

Protection

Employ “Active” Measures to Help Protect Your Home

Sprinklers. Most fire-prone municipalities require new residential construction to install an automatic sprinkler system. Going over and above, one can also install an exterior sprinkler system. These systems, like lawn sprinklers mounted on your roof, help to keep Zone 0 moist, such that falling embers don’t ignite. That said, when a fire is close enough and hot enough, any water distributed by these systems can evaporate almost instantly.

Fire Water Tank + Pump. If you live in a more rural area, you may want to invest in a fire water tank. These can be topped off using rainwater catchment, and are used to keep your vegetation green (less flammable). These systems can also serve as a backup water source for your sprinkler system and for fire department use. If you have a swimming pool, it too can serve as a fire water tank in case of emergency.

Fire Hydrant. Some properties may even want to consider installing a fire hydrant on the premises, adjacent to primary structures. Having a hydrant close by and available can help firefighters to protect your home. Especially in hard to reach urban/wildland interface areas, some fire marshals may even require you to install a dedicated fire hydrant prior to issuing a building permit.

Conclusion

Stacking as many of these strategies as possible can have a compounding impact on your project’s wildfire resiliency. But again, Mother Nature can be a vicious and dispassionate force. If you live in a fire prone area and a fire gets large enough, hot enough, and close enough, all of these strategies put together may not save your home or your life. Your family should always have at least two evacuation routes between your property and a safe meeting spot. Ask your local fire department for help with evacuation planning.

If you’re planning a new home, you’ll want to carefully consider all of these options and integrate them into a holistic approach. A highly-qualified architect is your best bet for synthesizing a solution that addresses these concerns in an elegant, cost effective, and aesthetically pleasing way.

There is no panacea. Great solutions require experience, talent, intelligence, and hard work.

If you are planning to build a new home in California, let’s talk.