Fire safety & soffit vents

[David Nebenzahl]

Following up on some recent threads here that had to do with house ventilation, particularly the installation of attic vents, I just read an article in one of my favorite papers (The /Berkeley Daily Planet/*) by one of my favorite columnists, their resident home inspector, Matt Cantor, in which he says that, at least in certain places in California, soffit vents are now going to be a thing of the past.

Basically, the deal is that such vents make it much too easy for fire to spread 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).

He discusses the fire safety aspect of vents, but doesn't address the ventilation issues raised by this: it looks as if it'll be back to the drawing board for venting attics. How will one be able to ventilate one's attic if one can't install soffit vents?

Anyhow, at least for folks living in certain areas, this is something you might ought to be aware of.

• The name is a complete misnomer, since the paper now only comes out once a week.

[jmeehan]

On Jul 4, 5:21=A0pm, David Nebenzahl wrote: =2E..

That would be a rather special case with limited application.

[HeyBub]

Okay, so soffit vents suck up floating embers wafting through the air, these glowing embers lodge in the attic (or somewhere), and the house catches fire. Makes sense, in a bizarre sort of way.

So, how do you ventilate the attic? Hmm.

• Dampers on the soffit vents? Kinda like storm windows. You close them when the fire/store gets close.

[Jim Rusling]

When we had a grass fire here a year ago, most of the houses that caught fire had wooden fences or dry bushes and the flame went up to the soffit and then into the attic. I was glad I had chain link fence and not a wooden one.

[David Nebenzahl]

On 7/4/2008 5:59 PM HeyBub spake thus:

Except that Murphy's Law, as you well know, will dictate that you're not at home when that happens ...

[HeyBub]

Yep. Still, the concept is an interesting intellectual challenge. So far I've come up with:

• Essentially nada.

[Norminn]

Seems that if flames and embers are close enough to go up into soffits, it is a lost cause anyway. The idea of having no soffits and roof vents seems kind of goofy, but that is what keeps California going - the absence of attic vents probably would eventually turn all the brown-outs to black-outs due to increasing energy consumption.

If fences, shrubs and trees are afire, absence of soffit vents ain't gonna save a house. A special circuit on a sprinkler system might - anyone doing that? Are there still wood shake roofs in high-risk areas? Anyone who hasn't seen a burning pine tree should arrange to do so - it is amazing. Pretty shrubs along the front of the home can turn into a blow torch.

[hallerb]

a weather radio remote control system could likely be set up pretty cheap to transmit a special tone ordering all homes to close vents......

although the right screening could likely also prvent fire thru the vents.

in the olden days miners carried real burning lamps covered with metal screen so they couldnt start fires ith the flame.....

metal creen with firproof mounting.

all new homes in california should be built of reinforced poured concrete,

[David Nebenzahl]

On 7/5/2008 5:43 AM HeyBub spake thus:

OK, how's this for an idea (inspired by your posting down yonder about running a downspout into a crawlspace)? Run a duct or three from the attic into the crawlspace to draw cool air from there. (This would only be practical for new construction or massive remodels, where one can build a chase through the house for the ducts, or is lucky enough to have the space left over from removing a chimney). Whaddya think?

[HeyBub]

I think that's swell. When I came up with a gutter downspout-like scheme, I thought "That won't work - it'll just draw up embers from near the ground" and discarded it. Your plan of pulling air from (perhaps) the center of the crawlspace is pretty good.

I don't think it would take a massive re-work; just unhook the downspout from the gutter and re-orient it to the soffit.

Of course, if the house is on a slab...

[dpb]

HeyBub wrote: ...

The article itself has two solutions coming to market now, apparently...

It would seem the latter of the two would be relatively simple to engineer and build.

While I can see there being an at least theoretical case, I wonder just what fraction of residence fires were actually owing to this mechanism and of those, how many wouldn't have had the issue if simply had had a reasonable firebreak distance around the dwelling.

Imo, a very high fraction of the structures lost are basically of the same nature as those flooded in a floodplain--comes w/ the territory and they're located where sensible folks ought not to be building in the first place.

--

[Bob M.]

How about screens? Can't believe no one has mentioned this. Steel or aluminum screens on the soffit vents do wonders in preventing things (bugs, birds, bees, hot fire embers) from entering. My house has had such screened vents since it was built in 1956.