Wildfire-resistant construction costs are similar to typical costs

Camp Fire drone photo
Photo taken on the Camp Fire by a drone in Magalia, California near Indian Drive.

With tens of thousands of homes being destroyed in the last year in California wildfires it should be a very high priority for home builders and local governments to swiftly adopt the practices that can greatly reduce the vulnerability of structures. It is not a given that if a large rapidly-spreading wildfire approaches a house it will ignite and burn to the ground.

Media reports sometimes marvel at how an occasional structure will be spared, and may describe it as miraculous or random. Instead, it is based on science. Some structures are designed, built, and maintained to be less vulnerable than others. The other half of the equation is what is within the home ignition zone — what will become fuel within 100 feet. If there is continuous vegetation or other flammable material in that zone that can carry the fire, especially close to the structure, it stands less chance of survival.

But for now let’s think about the structure itself. There are several useful reference guides for architects, home builders, and zoning boards containing information that can lead to designs and building codes that can help keep a fire from turning into a disaster.

• International Code Council’s International Wildland Urban Interface Code (IWUIC),
• National Fire Protection Association’s Standard for Reducing Structure Ignition Hazards from Wildland Fire (Standard 1144), and
• California Building Code Chapter 7A—Materials and Construction Methods for Exterior Wildfire Exposure.

Headwaters Economics compared the costs of new construction of a typical home vs. one with wildfire resistant standards for a three-bedroom, 2,500-square-foot, single-story, single-family home representative of wildland-urban interface building styles in southwest Montana. Below are excerpts from the article:

compare costs wildfire resistant homes

We examined costs in four vulnerable components of the home: the roof (including gutters, vents, and eaves), exterior walls (including windows and doors), decks, and near-home landscaping. Overall, the wildfire-resistant construction cost 2% less than the typical construction, with the greatest cost savings resulting from using wildfire-resistant fiber cement siding on exterior walls, in lieu of typical cedar plank siding. While cedar plank siding is typical in the wildland-urban interface of western Montana, fiber cement siding is already a common choice in many regions because of its relative affordability, durability and low maintenance needs. Wildfire-resistant changes to the roof resulted in the largest cost increase, with a 27% increase in gutters, vents, and soffits. The following sections describe the wildfire-resistant mitigations for each component.

Are planned communities safe from wildfires?

And, can we learn to adapt to fire?

Today I was reading an article about how the communities in Northern California are dealing with the risk from wildfire. One item that got my attention was where a “forestry and wildfire specialist” was quoted describing the Fountaingrove area of Santa Rosa which was devastated by the Tubbs Fire in October of last year.

…a housing development in a rural area that had been built following the highest fire safety standards. Vegetation had been cleared as required, and the homes were built of fire-resistant materials.

The article correctly stated that the development had been “reduced to ashes by the Tubbs Fire”.

“How could that have happened?”, I thought. Fire resistant building standards and cleared vegetation? Firefighters know that if those two characteristics can be checked off, a structure has a much better chance of survival. So how did the community get wiped out?

The Fountaingrove community is 4 miles north of the intersection of Highways 101 and 12 in Santa Rosa. The Tubbs Fire, the deadliest of the fires in 2017, burned into the north section of Santa Rosa, including the Fountaingrove area. It killed 22 people, destroyed 5,643 structures, and burned 36,807 acres.

map Pocket, Tubbs, Nuns, and Atlas
Map showing the perimeters of the Pocket, Tubbs, Nuns, and Atlas Fires. CAL FIRE October 15, 2017.

I would not call Fountaingrove a “rural area”. The thousands of homes there are very tightly packed, as you can see in the satellite photo below taken about five months before the Tubbs Fire.

Satellite photo Fountaingrove
Satellite photo of an area in Fountaingrove May 17, 2017, before the Tubbs Fire. Google Earth.

The next three photos are all of the same area, showing structures on Fir Ridge Road before and after the Tubbs Fire of October, 2017.

Fir Ridge Road
Fir Ridge Road area of Fountaingrove before the Tubbs Fire. Google Maps.
Satellite photo Fir Ridge Road
Satellite photo of the Fir Ridge Road area in Fountaingrove, June 16, 2017. Google Earth.
Satellite photo Fir Ridge Road
Satellite photo of the Fir Ridge Road area in Fountaingrove, October 17, 2017. Google Earth.

The photo below was taken before the fire, a few blocks south of the ones above. This home and all others around it burned.

South Ridge Road Fountaingrove
A home on South Ridge Road in Fountaingrove before the Tubbs Fire. Google Maps.

The Fountaingrove area burned in the 1964 Hanley fire. During the 53-year period until the next fire, the 2017 Tubbs Fire, the houses grew back along with a great deal of vegetation. Most of the homes have shrubs in the yards and multiple large trees, often between the houses that are very close together. Some of the structures are partially obscured from aerial photos by limbs hanging over the roofs.

It is difficult to tell if the homes in these photos were constructed of fire resistant materials. But it is clear that other Firewise principles were not being followed.

firewise wildfire risk home tree spacing
Firewise vegetation clearance recommendations. NFPA.

In a fireprone environment there should be no flammable material within 5 feet of a structure, and in the Home Ignition Zones 5 to 100 feet away, trees need to be 6 to 18 feet apart depending on the distance from the building. If on a slope, these distances have to be increased substantially.

An excellent video that elaborates on these principles has been produced by the NFPA. It points out that the areas in between the trees do not have to be nuked. But to be fire resistant they need to consist of green grass or fire resistant small plants, and should be raked or mowed close to the ground.

If a structure meets these Firewise guidelines, it stands a much better chance of surviving a wildfire. However, if the weather conditions are extreme, such as 60 mph winds and single digit humidity which can lead to spot fires igniting a mile ahead of the main fire, it can be difficult to save a structure.

Most homes are ignited not by the main flaming front of a fire, but from burning embers that land out ahead and start new fires. Likely receptors for these embers are leaves in a gutter, mulch, wooden decks, lawn furniture, attic vents, and accumulations of dead grass, pine needles, leaves, and other flammable material.

When a community is initially planned, the engineers may have done some things right, such as the design of the streets, and water systems. But if everything else is left up to the knowledge and discretion of developer and homeowner, very important principles might be ignored.

Fountaingrove did not meet all of the Firewise guidelines, but the streets were wide, making it easier for large fire trucks to access the structures. The very close spacing of the homes means that if one burns, the radiant heat alone can ignite its neighbor.

Other things to consider in mitigating the wildfire threat include multiple evacuation routes — if one becomes compromised by the fire, another could remain open. Large open spaces without flammable vegetation can serve as safety zones for residents who can’t escape. Backup electrical power sources that can keep pumps running so that community water tanks remain full can ensure firefighters have water at hydrants.

With the warming climate leading to extreme fires and fire seasons that are nearly year round, it is inevitable that deadly fires will strike many wildland-urban interface communities. Under the conditions we have seen in recent years, casually ignoring the threat will lead to more fatalities and property damage. It is not IF a fire will hit a fire prone area, but WHEN. The best solution is to learn to live with and adapt to fire, not ignore it.

Many factors can lead to an area being vulnerable to wildfire, including fire suppression leading to a buildup of vegetation, density of homes like at Fountaingrove, failure of homeowners to use Firewise principles, lack of community standards, insurance companies not understanding the issue, the federal government reducing expenditures for vegetation management and prescribed burning, lawsuits that halt vegetation management projects, and cutting the numbers of firefighters, air tankers, and Type 1 helicopters. When politicians take hold of just one of these issues while ignoring the rest, it can make it impossible to have a rational conversation about adapting to fire.

Discussions need to be thorough and nuanced, not politicized and influenced by industry that profits from using just a single, ill-conceived concept. And zeroing in on one vague term like “raking” and “poor forest management” simply confuse the general public when the complete picture is not illuminated.

A firefighter analyzes how the Carr Fire burned into Redding, California

When Royal Burnett retired he was Chief of the Shingletown Battalion of the Shasta-Trinity Ranger Unit in Northern California

Above: Screen shot from the video of the fire tornado filmed by the Helicopter Coordinator on the Carr Fire July 26, 2018 near Redding, California. 

When Chief Royal Burnett retired in 1993 his employer’s agency was still called California Department of Forestry (CDF). At that time he was Chief of the Shingletown Battalion of the Shasta-Trinity Ranger Unit in Northern California. Still keeping his hand in the game, Chief Burnett recently spent some time analyzing how the disastrous Carr Fire spread into his town, Redding, California in July of 2018.

“I retained my interest in fire and fuel modeling after retirement”, the Chief said, “and with my fire geek friends I try to keep current.”

Chief Burnett told us that when he left the CDF he was qualified as a Type 2 Incident Commander, Type 1 Operations Section Chief, Type 1 Planning Section Chief, and Fire Behavior Analyst. He has lived Redding, California for 40 years.

The article below that the Chief wrote about his analysis of the Carr Fire is used here with his permission. A version of it has previously appeared at anewscafe.


The Carr Fire burned 229,651 acres and 1,079 residences, about 800 in the county area and the remaining number inside the city limits.

My friends Steve Iverson, Terry Stinson and I spent several days looking at the portion of the Carr Fire burn where it entered the city of Redding. This would be the Urban portion of the Wildland Urban Interface. That part of our town is newer construction, high-end subdivision homes built to California’s “SRA Fire Safe Regulations”. That is, non-flammable roofs, stucco siding, and all the rest of the State’s requirements. How did we lose almost 300 of them in one wildfire?

Royal Burnett
Royal Burnett

Many of these homes were built right on the edge of the Sacramento River canyon on finger ridges to maximize the view, or on the rim of side draws — anything to maximize the view from the property and capture the afternoon up-canyon wind flow. Most had large concrete patios and some had pools. There were no wooden decks extending over the canyon that I saw.

The Canyon is about ½ mile across where most of the houses burned, with the slope estimated at around 100 percent. The aspect where most of the homes burned is west-facing, meaning it catches the afternoon sun and preheats the forest fuels.

The canyon itself was predominantly filled with manzanita 12 to 15 feet high (75 percent) and the remainder was oak woodland, with scattered ceanothus brush and poison oak . The brush field was approximately 75 years old, having sprouted after Shasta Dam was completed in 1945. Available fuel loading ranged from 1 to 3 tons per acre in the oak woodland to 13 tons per acre in the heavy brush. All herbaceous material was cured and live fuel moisture was approximately 80 percent in manzanita — right at the critical level, which means it will burn as if its a dead fuel, not a live one.

map Carr Fire Redding
The east side of the Carr Fire near Redding, California. Mapped August 26, 2017. Click to enlarge.

So, we’ve got a canyon filled with tons and tons of very flammable brush on an extremely steep slope with hundreds of very pricey homes perched on the rim, on a day when the temperature was 112 degrees and relative humidity was around 9 percent. To repeat a phrase from the 1960s, this was a “Design For Disaster”. (That was the title of fire training film describing the events of the Bel Air fire in Los Angeles County in 1961). [below]

We can determine how things burned by looking at burn patterns and other forensic evidence. For those who did this for a living its like reading a book. It was easy to figure out why the houses on the rim burned — they were looking right down the barrel of a blowtorch. Even though they had fire resistant construction, many had loaded their patios with flammable lawn furniture, tiki bars and flammable ornamental plants. Palm trees became flaming pillars, shredded bark became the fuse, junipers became napalm bombs.

Under current standards houses are build 6 to an acre; 10 feet to the property line and only 20 feet between houses. Once one house ignited, radiant heat could easily torch the next one.

We followed burned wood fence trails from lot to lot — wooden fences were nothing more than upright piles of kindling wood — and then into some ornamental shrubbery with an understory of shredded bark which torched and set the next house on fire. Then the fire progressed away from the canyon rim, not a wildland fire now, but a series of house fires, each contributing to the ignition of the next one.

We noted several, perhaps as many as a half dozen homes that burned from the ground up. Fire entered the building at the point where the stucco outer wall joined the slab and fire in the decorative bark was forced into the foam insulation and composition board sheeting under the stucco by the wind. Normally a fire in decorative bark is not a problem, it simply smolders. But in this case, where literally every burning ember was starting a spot fire and those spot fires were fanned by 100 mph in-draft wind, those smoldering fires were fanned into open flames which burned the homes. A simple piece of flashing could have prevented some of that loss.

We built homes to a fire resistant standard and then compromised them.

The fire hit Redding on an approximately two-mile front. It spotted across the Sacramento River in several locations and spread rapidly in the canyon, spawning numerous fire whirls. The updrafts caused the convection column to rotate, generating firestorm winds estimated at 140 mph. I’d guess most of the homes that were lost burned in the first hour after the fire crossed the river. The fire and rescue services were overwhelmed.

Sacramento River Redding
View from the Sacramento River in Redding north of the Sacramento River Trail Bridge. Google Street View. Click to enlarge.

The city of Redding allowed home construction on canyon rims, places that have proven to be fire traps over the years in almost every community where this construction has been allowed. Houses built in those exposed areas are similar to houses built in a flood zone. Its not a question IF they will burn, the question is When?

These subdivisions had limited egress. In one high-priced gated subdivision there is only one way in or out. Redding planners have seemingly ignored the lessons from past disasters like the Tunnel Fire in Oakland Hills in 1991 where 2,900 homes burned and 25 people died.

The city’s green belts have proven to be nothing but time bombs — fuel choked canyons that are a haven for her homeless. How many fire starts have we had in the canyon below Mercy Hospital, or in Sulfur Creek below Raley’s on Lake Boulevard? The homeless problem has exacerbated the fire problem. The fuels are there, the homeless provide the starts.

Even today, new subdivisions are being built overlooking the burned out canyons, looking across the rim at the ruins of homes burned in the Carr Fire.

The Sacramento River canyon will regrow, and it will be more flammable next time and stumps sprouting brush and noxious weeds will germinate in the burned area. The skeletons of the burned trees will become available fuel. In a couple of years the fuel bed will be more receptive to fire than it was before the Carr Fire.

If we don’t learn from our mistakes we are doomed to repeat them.

Thanks and a tip of the hat go out to Kelly.
Typos or errors, report them HERE.

Researchers study how the Fort McMurray fire ignited homes

screen-shot-2016-09-14-at-5-00-06-pmA preliminary report report released by the Institute for Catastrophic Loss Reduction looked at how the 1,500,000-acre Fort McMurray Fire ignited some of the 2,400 structures in the Alberta city in May of this year.

Below are excerpts from the document.

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After evaluating the fire environment and clearances between homes and the forest edge, the investigator discounted direct contact from flames or radiant heat of the forest fire as being significant sources of home ignition at Fort McMurray. Instead, it was concluded that wind-driven embers were the most probable cause for the majority of early home ignitions in the zone where the fire made its transition from forest into urban neighbourhoods. Once established, the fire would have spread from structure to structure as an urban conflagration, accounting for the majority of home losses.

home ignition zone
NFPA

In all neighbourhoods studied, homes whose owners had adopted FireSmart guidelines survived much more frequently than homes where they had not, despite the extraordinarily harsh conditions.

Recommended FireSmart guidelines work. They are effective in reducing the probability of home ignition and wildfire losses. Home survival does not appear to be random or a matter of luck.

Home survival depends on conditions in the home ignition zone, for which owners are responsible.

While low total hazard rating is important, a single critical weakness can lead to home loss.

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Articles on Wildfire Today tagged “Fort McMurrary Fire”.

NIST releases report on Waldo Canyon Fire that burned 344 homes and killed two people

waldo canyon fireThe National Institute of Standards and Technology has released a lengthy report on the Waldo Canyon Fire that burned 344 homes and killed two people in Colorado Springs, Colorado in June, 2012. (It can be downloaded here, but is a large file.)

The 216-page document covers firefighting tactics, how structures ignited, defensible space, and how the fire spread, but does not address to any significant extent the management, planning, coordination, and cooperation between agencies, which were some of the largest issues.

The report was put together by five people, Alexander Maranghides, Derek McNamara, Robert Vihnanek, Joseph Restaino, and Carrie Leland.

At least three official reports have been written about the Waldo Canyon Fire, two from the city of Colorado Springs (here and here) and a third from the county sheriff’s office. However one of the most revealing was the result of an independent investigation by a newspaper, the Colorado Springs Independentwhich revealed facts that were left out of the government-issued documents, including numerous examples of mismanagement by the city before and during the event.

The fire was first reported the evening of June 22, 2012 on the Pike National Forest. Due at least in part to the anemic response from the U.S. Forest Service, the fire was not located until after noon the following day. No aircraft were requested until firefighters were at the fire, more than 16 hours after the initial report.

The day the fire started there were eight large fires burning in Colorado and 16 uncontained large fires in the country. Four days later on June 26 when the Waldo Canyon Fire moved into Colorado Springs burning 344 homes and killing two people, there were 29 uncontained large fires burning in the United States.

However there were only nine large air tankers in the United States on U.S. Forest Service exclusive use contracts, down from the 44 we had 10 years before.

The 7-page Executive Summary of this newest report lists 4 primary findings, 37 technical findings, and 13 primary recommendations.

Primary findings:

  1. Defensive actions were effective in suppressing burning structures and containing the Waldo Canyon fire.
  2. Pre-fire planning is essential to enabling safe, effective, and rapid deployment of firefighting resources in WUI fires. Effective pre-fire planning requires a better understanding of exposure and vulnerabilities. This is necessary because of the very rapid development of WUI fires.
  3. Current concepts of defensible space do not account for hazards of burning primary structures, hazards presented by embers and the hazards outside of the home ignition zone.
  4. During and/or shortly after an incident, with limited damage assessment resources available, the collection of structure damage data will enable the identification of structure ignition vulnerabilities.

Three of the technical recommendations:

  • Fire departments should develop, plan, train and practice standard operating procedures for responding to WUI fires in their specific communities. These procedures should result from scientifically mapping a community’s high- and low-risk areas of exposure to both the fire and embers generated during WUI events (as will be possible using the WUI Hazard Scale).
  • A “response time threshold” for WUI fires should be established for each community. Fire departments have optimal “time-to-response” standards for reaching urban fires. Similar thresholds can, and should be, set for WUI fires.
  • High-density structure-to-structure spacing in a community should be identified and considered in WUI fire response plans. In the Waldo Canyon fire, the majority of homes destroyed were ignited by fire and embers coming from other nearby residences already on fire. Based on this observation, the researchers concluded that structure spatial arrangements in a community must be a major consideration when planning for WUI fires.

Primary recommendations:

Continue reading “NIST releases report on Waldo Canyon Fire that burned 344 homes and killed two people”

Radiant heat, embers, and the ignitability of structures

Here are a couple of interesting videos featuring Jack Cohen, a researcher at the Missoula Fire Science Lab. The videos explain radiant heat and how difficult it is for fine fuels and structures to ignite from that alone, and the role of embers in spreading fire and burning structures.