Home & Garden Columns

About the House: California is Burning

By Matt Cantor
Thursday July 03, 2008 - 10:17:00 AM

California is burning down. This is the real Shock and Awe. As of this writing, there are over 1,300 fires burning in the state and nearly a third of a million acres have burned. Since I’m not good with acres, I decided to convert this to square miles. At 640 acres to a square mile, this means that close to 500 square miles have burned. Again, I’m not that good with areas so I like to find something to compare this with. The city of Los Angeles is about 500 square miles. San Francisco is less than half that size. Imagine, two San Franciscos have completely burned down in this recent spate of fires. We’ve currently got over 17,000 fire personnel working on fighting these fires, over a thousand engines in the field, three hundred bull dozers cutting fire breaks and 85 helicopters (mostly dropping water on these many blazes). 

When I started collecting data to write about the new fire code in the recently revised California Building Code, I had no idea that my lead would be quite so dramatic but there it is. The Flying Spaghetti monster provides (may its tentically appendages be praised). 

Not a second too soon, California has built a whole new set of standards to apply to the construction of houses situated near wildlands where fire can wander in from the woods and snuff out that largest of our investments. This is pretty smart stuff and while I often take issue with what I find in the building code, I would like to offer high praise to the folks that created the Wildland Urban Interface or WUI portion of the new California Building Code (CBC). 

The new Chapter 7A of the CBC, which deals exclusively with WUI is pretty tough reading but I’ll try to give you basics. Firstly, these are not things that you will be forced to do to your existing home unless you are in the process of doing significant levels of remodeling. They are also not things that you need to do on all properties. They only apply to WUI. To find out if you’re in one of these areas, you can go to http://firecenter.berkeley.edu/fhsz and enter an address in the box. You can also check at http://www.fire.ca.gov/fire_prevention/fire_prevention_wildland_zones_maps.php if the first one doesn’t work.  

The problem with these maps is that they serve two jurisdictions, the State Responsibility Area or SRA or the Local Responsibility Area or LRA. This is how the state is divvying up all the work of figuring out who oversees these regions. I didn’t have too much trouble finding a map of the Berkeley area and not too surprisingly, most of the Berkeley hills were included at various levels of severity. The CBC says that the highest severity will set a higher standard for certain of the features I’m going to talk about (such as required roofing type) but it’s easiest just to think of the entire area as having similar new requirements.  

I’d also like to say that anyone who takes a bit of this knowledge and uses it on their existing home is worthy of admiration and envy. I was surprised at how simple most of these things were and the degree to which a large body of statistical data has been converted into a very small set of advisories.  

The first thing that will surprise no one is that the old 30 foot perimeter of defensible space has been enlarged to a 100 foot zone of fuel modification. In short, the state is saying that we need to look closely at a larger area to see what shrubs, dry grass, trees and other vulnerable fuel nearby may be. The local fire marshals will have to make the call but, in short, we’re being asked to widen the area of interest with regards to burnable material.  

Locally, and statewide, I have been, for years, appalled at the lax attitude that we have about overgrowth. Fires just happen and the deeper we get in our little hobbit-like dells of trees and grass, the more likely we are to see it all swept away in a few short hours. Many Berkeley residents aren’t aware that just 85 years ago, a fire swept across North Berkeley, destroying roughly 600 homes (not to mention 3000 home lost in ‘91). If we don’t lower our fuel supply (trees, shrubs, grass) it can happen again. Also, most of the fires happening in the state today are the simple result of lightening! Tell that to Smokey the Bear; but as usual, I digress. 

After defensive space, the next area of concern is around ventilation. Most homes today have both attic and foundation vents. Both are an issue in the new WUI code. Vents normally found in the eaves or “soffits” (the undersides of enclosed eaves) are completely eliminated in the new code since we have discovered that these area of the building are particularly vulnerable to sparks, embers and brands (bits of burning wood).  

As fire sweeps up over the building (much like a wind), it is captured under the eaves and induces the penetration of burning matter. By sealing the soffit or eave, we greatly reduce our risk of fire. Roof edges are also requested to include thick fascia (or barge) boards that help to resist burning. 

While crawlspaces can still have air vents, these must now be made to improved specifications. The new code is struggling to find itself in places like this and starts by demanding at least a fourth-of-an-inch mesh to be used; however, this will not stand.  

Steve Quarles, who helps to disseminate (and research) these new standards for the state fire Marshall, says that fourth-of-an-inch mesh can easily allow sparks and embers to shoot into the crawlspace leading to fire. A range of new vents for both crawlspace and roof (now exclusively placed on top of the roof surface in the WUI) are just now arriving from the manufacturing sector.  

The aptly named Brandguard is one such vent. We will also soon see Vulcan, a suitably logical design employing a tight mesh coated with an intumescent paint that puffs up and seals the vent when heated (sort of the puffer fish approach). Fireguard has a fire activated baffle that will physically close when sufficiently heated. 

Roofing materials are also key but this is one of the ways in which we get off easy. Common asphalt shingle is surprisingly fire retardant and is, perhaps, the cheapest roofing material available. Not so obvious is the fact that metal such as aluminum valley flashing is not fire retardant and can easily melt through leading to fire. The good news is that it’s really easy to solve that one too (just put some asphalt roofing below the metal. 

Wood roofs CAN get passable fire ratings but I confess that I’m slow to come to that party. With good cheap choices such as compo (asphalt) shingle and obvious ones like ceramic or concrete tile, why bother with wood shake or shingle. Some communities, such as L.A. are no longer allowing wood products and I suspect that, with time, this argument will open and shut for us all. 

Two more short bits and then we’re done, this being a bit long of wind. Sidings are not a major issue according to Maestro Quarles since fire rarely ventures through the siding (unless there are gaps) and even common wood sidings should be fine. Windows on the other hand are a major issue and recent fire statistic showed that houses with double glazed windows were far less likely to burn than those with single glazing. Apparently, that insulating effect is even more impressive under these nasty circumstances than in the simple matter of keeping your heating bill down.  

If tempering is added to one side of the double glazed panel, the window will meet the WUI requirements. Word is that most window makers will be providing two sheets of tempered glass anyway, since it’s actually easier to make them that way. Tempered double glass windows might really save your house in a fire and if you’re in a heavily wooded canyon, you might just think about this investment. Windows explode as fire approaches and then there’s not much to do but get out the marshmallows. 

Decks are my last item (not that I’ll cover this code completely) and they are no small contributor to major loss during wildfire. Decks have a special vulnerability but may meet the new code in any of several ways. Most areas will meet the requirements by being built of redwood but some jurisdictions may require thicker beams, thicker decking or enclosure of the understructure. Again, it’s that wind-of-fire thing. If you can protect the building against the blowing embers and brands that want to fly up under things, you’re more than halfway there. 

If you own a house that you feel is vulnerable. Start with what’s cheap or easy. Close off gaps and holes. Change vents and close off the eaves. Take a look at your roof. Is it open at edges or covered in a wooden material? Don’t forget to think about double glazed or tempered windows. They might be worth it? (what are you paying for fire insurance?) 

Some local fire marshals are taking a tough approach. Identify properties that lack defensible space, cite them for violation and, after a month or two, do the job themselves and bill the owner through the tax roles. I hope that our local fire officials are listening.  

It’s not cheap, I know but then again, houses aren’t either.