Press "Enter" to skip to content

Save Class K

The Mendocino Board of Supervisors is looking to change our Class K Building Ordinance and require all manner of new building materials and techniques, despite the high cost, and despite the fact that California building regulations still offers amended options for owner-built rural dwellings. With the aim of preserving affordable housing options in our county, we’ve done a bit of research into California’s building codes, to better understand the issues and to offer a more educated defense of maintaining affordable and creative building opportunities in Mendocino.

The Class K Building Ordinance exists to “provide minimum requirements for… limited density rural dwellings and appurtenant structures” and “to permit the use of ingenuity and preferences of the builder.” The Class K Ordinance further states that the adoption of these amended regulations “is reasonably necessary because …Mendocino County has a severe housing shortage. Low cost housing is especially hard to find in the County and the adoption of regulations for limited density rural dwellings will encourage the further construction of such dwellings. State law mandates the County of Mendocino to adopt a General Plan which makes adequate provisions for housing its citizens.” And finally, these amended building regulations are “necessary so that County residents may be provided housing at a cost affordable to themselves and to the county of Mendocino”.

These articulate arguments, based on and sanctioned by California’s Title 24 Building Standards Code and Title 25 Housing and Community Development Regulations, were written in the 1980s by our County Supervisors to explain the need for amended building regulations that support California affordable housing mandates and help address Mendocino housing shortages. In the nearly 40 years since this was published, our housing needs have become more extreme, and our state government more adamant that counties must make affordable housing options available to their residents or face legal consequences. Today’s Titles 24 and Title 25 still endorse those Class K goals.

On February 6, the Board of Supervisors will be entertaining proposals to change Class K in ways that would significantly hamper owner/builders from constructing affordable housing. We would like to address the proposed items point-by-point to make certain, while still adhering to the State’s health and safety standards, that no unnecessary regulations are added, no undo costs are incurred, and no building hurdles imposed that might deepen our housing crisis and make our county vulnerable to penalties and legal challenges.

* * *

A new single family residence shall be limited to 2,000 square feet of habitable space under Class K. An additional 800 square foot attachment would be permitted.

This is a good idea. Capping the size at 2000 square feet is quite compatible with affordable housing goals, and limiting the size will significantly lower fire risks.

This would, furthermore, close a loophole for people who would take advantage of Class K and create fire hazards by constructing excessively large structures.

A perimeter foundation, as required by California Building Code (CBC), shall be required under all new single family residences, and all accessory structures greater than one story in height, unless otherwise determined by an engineer.

The California Residential Code [Title 24, Part 2.5, Chapter 9, R301. 1.1.1] specifically states that for limited-density owner-built rural dwellings, “Pier foundations, stone masonry footings and foundations, pressure-treated lumber, poles or equivalent foundation materials or designs may be used provided that bearing is sufficient.”

So perimeter foundations are NOT required by CBC, and owner-builders of rural dwellings seeking affordable housing may opt for less expensive foundation types.

Wildland Urban Interface (WUI) requirements apply to all new family residential structures.

Title 24, Part 2.5, Chapter 9 specifies that for limited-density owner-built rural dwellings, owner-produced or used lumber may be used.7

Class K and Title 25 encourage and support ingenuity and builder preferences.

Title 24 Building Codes allow for alternative methods of achieving the goals of the minimum standards.

The Building Department should have educational literature to share with Class K applicants on standard and alternative building materials that limit fire spread.

Any costly building requirements should be offset by property tax incentives.

All future Class K structures come into compliance with CA State Law and require automatic fire sprinklers in all single family residential structures.

There are many ways to reduce fire risk, but sprinkler systems are one of the more costly, adding $10,000-$14,000 or more to construction costs (for a 2000 square foot home) and requiring them is therefore not in keeping with CA affordable housing goals.

Title 25 specifies that limited density owner-built rural dwellings are to be allowed to use their ingenuity in the pursuit of health and safety. Title 25, Article 8’s purpose is to facilitate alternative approaches to meet building health and safety goals.

The leading advocate for fire sprinklers is the National Fire Protection Association (NFPA), a trade union that was formed in 1896 for the express purpose of lobbying for fire sprinkler systems! They keep strong statistics on fires and deaths, but they no longer record and report instances of sprinkler failure They are a biased source.

California is one of only three states that require fire sprinkler systems for standard residential construction, 31 states have no fire sprinklers legislation, and a whopping 17 states that actually prohibit state and county requirements of fire sprinklers!

Indoor fire sprinklers have no impact on wild land fires.

Multiple other factors can contribute to flammability. House size is a key factor, and a square footage cap, if adopted, will greatly lower the risk of adverse effects of fire.

If owner/builders of low-density rural dwellings would prefer to apply their ingenuity to the goal of protecting themselves and their property from the adverse effects of fire, the Building Department should accept their proposals.

The State political tide favors housing advocacy.

Three (3) inspections will be required to obtain a Class K permit.

Title 25 (§ 108-112) and Class K (§ 18.23.170) already provide for at least one single inspection and any additional inspections that may be needed.

Class K Ordinance shall state that the most recently adopted version of the Uniform Building Code (UBC) would be the operative code. This would avoid the necessity of having to re-adopt Class K revisions.

This is an alarming proposition. Any changes to Class K Ordinance require amending the General Plan, and for good reason. Class K Ordinance is currently part of the Mendocino Housing Element of the General Plan.18

General Plan protocol encourages public input and maintains transparency of purpose.

Let’s not curtail democratic principles for convenience sake or to avoid public input.


  1. Alan Brinson January 25, 2018

    This came up in today’s news reports of sprinklers. NFPA is not a union, it is an internationally respected professional membership organisation that writes fire protection standards, many of which are ANSI standards. Have a look at its web site and you can freely download its recent statistical analysis of sprinklers. It includes several pages about sprinkler failures. I live in the UK and don’t know the details of the rest of your article but since you have everything wrong in the part I do know, perhaps you are wrong about the rest as well.

  2. Phil January 25, 2018

    ‘internationally respected professional membership’ – It is in fact a lobby group. Don’t know about the UK but since you are wrong about this then you are, perhaps, wrong about the rest as well.

  3. Lee January 25, 2018

    Re: wild land fires and sprinklers
    An article by James Dunn posted January 9, 2018, on, Santa Rosa, California, said not many buildings in Sonoma County have sprinklers on the outside. Fountaingrove Athletic Club has sprinklers under its wide walkways that surround part of the building.
    On October 9 when the Tubbs Fire roared into Santa Rosa, staff members had left a large bin full of towels in the walkway outside next to the athletic-club building. The bin sat directly under one of the sprinklers. There was no one in the club at the time.
    Flames incinerated grapevines on the hillside that slopes down toward Fountaingrove Athletic Club and howled around the building, setting fire to the towels. When heat and smoke rose into the sensors, sprinklers likely activated all around the perimeter of the structure. The sprinklers probably saved the building even as nearby tennis courts were scorched and the elegant Fountaingrove Golf clubhouse just up the roadway from the athletic club burned in minutes into charred, twisted rubble.
    “This is my theory,” said Caroline Wilcox, operations manager at the athletic club. “The day we had the fire (Sunday, October 8) was very warm. We were very busy that day. We have bins of towels.”
    She points to one bin. “This bin caught on fire,” Wilcox said. “It had a bunch of towels stacked on it. It got so hot, our fire sprinklers came on at the outside perimeter of this building. That’s what saved the building. Soot got in under the door (in the crack)” from the burned towels. The ceiling under the outdoor eaves appeared singed from the small towel fire.
    Indoor sprinklers did not go off.
    “I’m very thankful that we still have this building,” said Wilcox, who has worked at the club for 12 years.

  4. stephen m murphy January 29, 2018

    Exterior sprinklers be praised, currently next to none, the only building products I am aware of that are resistant to the ultra hi-temps of Venturi prone wildlands fire [ 3000+degree] are heavy guage metallics, masonary and ceramics.

    Speaking of ceramics, there are numerous engineered configurations of the asbestos replacement by alumina silicate compounds,re: space tiles…now being produced in many forms, blanket,batting,woven fabric, rope etc.

    Cementacious applications of alumina silicate fiber as a plaster medium may be considered. Such mortars currently exist.

  5. Off The Grid January 31, 2018

    So how do we save Class K?
    How can we object to some of these changes?

    Here’s a nice story on inside fire sprinklers:
    Extreme cold temps caused the fire sprinkler pipes to break in the ceiling of a vacation home here in Mendocino County. Water sprayed inside the house for well over a week, completely ruining the home from ceiling to floor.
    The insurance company denied the claim (digging for anything they could find which was a discrepancy on the location of the building on the lot).

    I built my Class K home off the grid with a pier foundation.
    We had a wonderful experience not having to deal with strict regulations and constant inspections (I took pics of everything anyway)
    My concern with interior fire sprinklers is that they would cause more damage inside the home. I would not mind an exterior sprinkler system, which is what we did.
    we ran Pex for our interior water lines. If my PEX ever bursts due to extreme cold temps (which should never happen), my only concern will be to replace the flooring (which is vinyl and probably won’t be damaged) and possibly the cabinets under the sink.

  6. Fred Durso February 6, 2018

    NFPA is sympathetic to the housing struggles expressed in this piece. However, there are inaccuracies about the impact of home fire sprinklers and our organization that need to be addressed.

    NFPA is a nonprofit organization with a mission to eliminate the losses associated with fire and related hazards. The author’s claim that NFPA is a “trade union” lobbying for fire sprinklers systems is false. Our code-making process is open and consensus-based. Codes and standards are developed and updated by volunteer technical committees made up of individuals who represent balance of interests. No single interest can have a majority.

    As a fire and life safety organization, we advocate for the increased use of home fire sprinklers due to its life-saving ability; sprinklers reduce the risk of dying by 80 percent, states our research. Our interest is safety. We do not have a monetary interest in this technology.

    Moreover, our research points to the cost-effectiveness of fire sprinklers in new homes. Our latest cost study indicates that, nationally, the cost to sprinkler a new home averages about $1.35 per sprinklered square foot. The majority of California towns examined in our cost study had a sprinklered cost per square foot well below the national average. Homeowners spend more for flooring or kitchen granite countertops than they did for home fire sprinklers.

    The claim that NFPA “no longer record[s] and report[s] instances of sprinkler failure” is also not true. Our 2017 “U.S. Experience with Sprinklers” report states that sprinklers operated in 94 percent of home fires in which sprinklers were present and fires were considered large enough to activate them. They were effective at controlling the fire in 96 percent of fires in which they operated. In three of every five home fires in which sprinklers failed to operate, the system had been shut off. The report discusses both the high reliability and effectiveness of sprinklers and reasons for problems on the rare occasions when they occur.

    NFPA would be happy to talk further on this issue, to provide a better understanding on our position and the research that supports it. Feel free to contact us anytime at

Leave a Reply

Your email address will not be published. Required fields are marked *