Residential Fire Hardening

In the Tahoe region, summer has arrived. Creeks a full of rushing snowmelt and wildflowers are blooming. And while we all get out to enjoy the warmer weather and summer mountain sports, in the back of everyone’s minds is the worry of impending fire season. How long until the smoke rolls in? Will our projects be affected? Will our homes?

Arial photo of untouched home surrounded by burnt forest
Source: Joe Amon/Getty Images, accessed 20 June 2022, <https://www.sciencenews.org/article/how-to-protect-your-home-from-disasters-climate-change>

“Fire Season” is hardly accurate anymore, as years of drought and human influence has created year-round potential for fires on the West Coast. We know, at some point, our projects will be threatened by fire, and so, at JKAE it is important to consider this with every project, from conception to specifications.


Graphic showing Weather, Topography, and Fuel
Source: IBHS Primer Series July 2020, Fire Behavior Triangle, Part one The Fire Behavior Triangle, accessed 6 June 2022, <https://ibhs.org/wp-content/uploads/wpmembers/files/wildfire-primer-series-part-1_triangle.pdf>

The Fire Behavior Triangle names three areas which can increase the risk of wildfire to buildings: Fuel, Topography, and Weather. While we cannot control when and where these fires will start, we can influence the properties we work on. At a recent Sierra CAMP Workshop, when I asked what professional designers should be doing to support wildfire interface, Wildland Fire and Fuels Specialist Taro Pusina responded that we should assume there will be no or limited fire responding entities when the wildfire come through the community, so make the property, landscaping, and home more capable of withstanding fire and a place which fire respondents will want to post up at.


But for so many reasons, very few people want to live in a concrete bunker. And cost is something worth considering as well. How do we balance making fire protection a priority when it sometimes comes in conflict with other project goals, such as function, enjoyment, and aesthetics? Where is it most effective to invest budget and effort?


Fuels

Current building codes, such as the Wildland Urban Interface codes, and agency building guidelines, such as those issued by fire departments, mandate certain levels of fire hardening of newly built structures. These create an outer shell less susceptible to fires than older homes. But we can go further.


Since most structure loss is a result of embers ignition, as opposed to direct spread or radiant spread, choose, and assemble materials in a way the prevents opportunity for those embers to take hold. Creating a tight envelope that considers how embers are most likely to move across a property, where debris is mostly likely to accumulate, and where the weak points are, takes the code further.


Spanish tile roof with broken shingles and exposed plywood
Source: Michael Vi, Broken clay roof tile, Getty Images, accessed 10 June 2022, <https://www.gettyimages.com/detail/photo/broken-clay-roof-tile-royalty-free-image/1190298362?utm_medium=organic&utm_source=google&utm_campaign=iptcurl>

For example, Spanish tile roofs are considered a Class A covering (the most effective against severe fire testing exposures) because the material itself is non-combustible. It might seem like a great material to use. But often the layering of materials creates nooks and crannies where debris can accumulate, and embers can pass through. Pockets of kindling develop a break in the house defenses. Fire consideration, and other factors like aesthetics and snow, is why you will see so many metal roofs on JKAE projects.


Topography

The mountains are a beautiful place to live in. The steepest of areas open up to views of lakes and valleys. So, there is a desire to perch homes on the precipice of a site. This is also one of the most fire hazard prone places for a structure.


Sketch of Upslope Winds
Source: Kathryn Brower, Sketch of Upslope Winds, 2022

Winds tend to carry fire uphill, through canyons and saddles, carrying those embers with them and driving direct spread fire upward. Placing vertical, non-combustible obstructions, such as retaining walls can redirect wind, which tends to follow the slope of the hill. And it creates a blockade to direct spread fires.


Site plan of fire hazards on proposed property
JK Architecture Engineering, Fire Study, 2021

Positioning structures downwind of water features, ponds, and pools creates a blockade as well. Additionally, some fire districts will keep information about available water resources during a fire, so the added step of communicating that with the local fire department makes the home more attractive to a fire response to as a place which would be possible to hold and fight a wildfire.


Climate

As much as an office with so many skiers would love to control the weather (consistent Friday blizzards would be the new weather pattern), we cannot. Not directly anyway. Prioritizing sustainability does influence climate though. Guiding clients towards more sustainable materials, considering solar design for the site, pushing towards more efficient envelopes and temperature control, and building to last are just some of the ways which we can slow climate change.


We take the calculated risk of life outside of a bunker. Above are just a few ways we mitigate that risk, which collectively makes a difference in creating safer homes for our clients, but also safer communities and a safer region. It is a satisfying aspect of the job when a project becomes an asset to fire responders and not a burden.

 

Resources for Expanding Knowledge

https://fireadaptednetwork.org/

https://www.livingwithfire.com/

https://defensiblespace.org/


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