Fire Safe News

Is Adding Housing Density Near Our Canyons Insane?

“Fire-ey Questions …from Your Neighbors” article in the November 2023 edition of the MetroView.

By Judy Beust Harrington, Co-Chair, Kensington Fire Safe

Kensington’s fire safe council will share our researched answers to inquiries from community members here. Please send your fire-related questions to  Pictures really appreciated too!

Q: “What does Kensington Fire Safe think about new, multi-unit ADUs along the canyon rim?”  …asks local resident, Sandra Johnson.

A: Sandra, we’re not experts on much of anything, but as someone who lives where the 1985 Normal Heights fire destroyed 75 houses– you’ve no doubt heard a lot about how fast that fire spread, how far embers flew, and the challenges of evacuating a lot of folks quickly.  

Apparently Sandra and her neighbors are now facing an “accessory dwelling unit” issue head on with a nearby Normal Heights property, where nine – yes, NINE –  additional units are planned on a small, single-family lot.  State law only requires that one ADU and one “junior” (1) ADU be allowed in a single-family zone, but as many of you have no doubt read, San Diego has chosen to go significantly beyond that limited but pretty reasonable requirement.

Of course, more affordable housing is essential for San Diego, but doesn’t common-sense scream against adding a lot of density to City and State-designated “Very High Fire Hazard Severity Zones” (VHFHSZs – not a great acronym).  

Turns out, like most things, the situation is much more complicated than it looks, as Sandy helped us discover.  Some of the issues:

Is Code Compliance Enough?

The City’s Bonus ADU program allows virtually unlimited housing units in the city-designated “Sustainable Development Areas.”(1)  However, developers are required to meet upgraded codes that further dictate approved materials and construction methods to mitigate exterior wildfire exposure. With Sandra’s help, we reached out to Fire Department officials with some very specific questions and learned that there are significant fire-resistant requirements that do make an enormous difference in the home’s survival rate.  

In the 2017 Thomas Fire, more than 90 percent of the structures destroyed were reported to have fire-resistant construction..(2)   Maybe upgraded codes since then would help bring that percentage down, but how much? While it sounds like the newer standards reduce the likelihood of embers igniting a structure, thus slowing the fire’s spread, they don’t render homes fireproof. In the event of a blaze, occupants must still get out fast. 

A study of the 2018 Camp Fire showed that distance from nearby structures was one of the strongest predictors of a home surviving the blaze (3)  There’s no way around the fact that ADUs can radically reduce the distance between residentials structures. Just look at these pictures of some current ADU additions, curtesy of Neighbors for a Better San Diego.

Density Dangers

Will more people reduce safe egress?  A quick look at a Google Earth map shows how extremely limited escape routes are in many of our canyon areas. In some cases, streets nearest the canyons have only one narrow street in and out. Prime example: East Alder area, the site of a canyon fire in 2019.  Increasing our “population-to-evacuation route ratios” may increase dangers to residents and firefighters.  Should probably make that a definite “will.”

More people, less water pressure?  One of the reported issues in the Normal Heights fire was lack of sufficient water pressure.   Although water pipes in some neighborhoods have been upgraded, what is the potential impact of this much additional density on the water system?  We couldn’t find evidence that issue was addressed.

More people, more resources?  The city can’t keep up with current canyon brush management needs – yet alone do more to protect a higher population on the canyon rim.  And will our firefighters get more resources when more fires start in additional kitchens, backyard BBQ grills or fire pit flames?   Kensington already had some large flames from a BBQ grill on Alder.

Added homeowner insurance challenges?  Large developers can self-insure, but individual homeowners and renters increasingly face few options, as major insurers withdraw from our market, deny coverage, or impose unmanageable rate increases.  It’s not hard to believe that additional density in canyon areas won’t cause insurers additional reasons to stay away.

Of course, California insurance Commissioner Lara is allowing more rate-setting flexibility to entice insurers to stay or come back.  Overall good news – maybe the FAIR plan won’t go broke – but it likely means ever-higher rates.   Some residents may then feel forced to go bare and end up in even more dire straits in the event of a fire destroying their home.  While no one died in the flames of the 1985 Normal Heights Fire, we’ve been told there were deaths soon afterwards, many of whom were elderly and had no insurance to cover their loss.

Are Just Our Canyon Rim Areas VHFHSZs?

Trying to limit excessive density increases in Very High Fire Hazard Severity Zones sounds reasonable on the surface, but with over 150 urban canyons, close to half of our city is designated very high fire hazard!  So that idea is pretty much DOA.  

It’s the City’s Bonus ADU program that apparently allows virtually unlimited ADUs within one mile walking distance from a major transit stop. According to a Neighbors for a Better San Diego analysis, in our city, 40.3% of the 65,010 parcels that one-mile covers are also in VHFHSZs.(4)    But, again, State law only requires that one ADU and one junior ADU be allowed on a single-family zoned lot.  Changing that to half a mile away from a major transit stop could reduce that number of included parcels to 27,871, although 31.6% would still be in VHFHSZs.  A huge improvement, but is half a mile away always far from a canyon rim?

What to do?

The issue is far more complex that I fully understand or could cover in this article, but no matter what, increasing density in communities very close to canyons defies common sense. One or two small ADUs should be enough where there’s extra high fire risk, we shouldn’t have a nine-plex going up on a canyon rim. 

Please make your voice for fire safety heard!