Wondering if anybody has any ideas about how to make a good-looking and fire-resistant vented roof now that soffit vents are illegal in our high fire danger area?
The standard workaround uses little plastic vents in the top of the roof set back a bit from the eave for input air, and a ridge vent for exit of hot air. But these in-roof vents look awful, plus probably aren’t fire resistant either. (Plastic melts.) Also, I suspect they’d let snow melt flow into the roof structure.
Anybody got any experience with this issue and come up with a good solution?
Replies
I think I'd go with a hot roof and be done with it.
Though there is a vented drip edge available that might slip through the cracks in the regulations.
Just curious...what about the old style gable end vents? Are they illegal too?
Seems like it should be possible to shield them from flames or add a flame sensitive, spring-loaded mechanism to close up mechanical louvers.
Whaddaya think McD? Am I on to somethin'? Is this a better mousetrap?
You design it and I'll sell it. :-)
Probably difficult to design a thermal sensor that will trigger soon enough in a fire and not on a hot, sunny day.
If your view never changes you're following the wrong leader
difficult to design a thermal sensor that will trigger soon enough in a fire and not on a hot, sunny day.
A standard 180º fusible link ought to work, the 165º "quick-acting" ones would also suffice--the real trick is in designing a vent that has positive fire stopping on demand. Not something that suggests that it would lend itself to the low-tech of gravity soffit & ridge venting.Occupational hazard of my occupation not being around (sorry Bubba)
165F is a temp that is easily achieved in a hot attic under the right conditions. 180F is iffy.
If your view never changes you're following the wrong leader
165F is a temp that is easily achieved in a hot attic under the right conditions
Actually, I hope not <g>. But, I may have also reverted to "mad dog & englishman" logic on those occasions where traversing a residential attic would have been that hot.
I do not have a peak reading for my present attic (been too lazy to install recording thermocouples, the remote thermometer sensor stops reading at 121º). Previous measurements here in my area run 130-140º (just like your car, venting--cracking opne a window--gets you about 4-5º cooler). I've not lost a fusible link in the car, but I've never left one in there for 60-70 straight days, either.Occupational hazard of my occupation not being around (sorry Bubba)
"165F is a temp that is easily achieved in a hot attic under the right conditions."
Not in a well-vented roof!
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
The idea I proposed was gable end louvered vents, machically linked and spring loaded to close tight when triggered by an appropriate heat sensor. I suppose that the sensor would be mounted externally, out of direct sunlight.
But gable end vents are just shy of worthless.
If your view never changes you're following the wrong leader
Dan- i think MOST roof vents are worthless.
Gable end vents have the virtue( at least here) of having been dependably leak free for a couple hundred years---and they are easy to fit with a power fan with a thermastat/humidistat if the custermer wants to further delude themself that the vent is doing something, LOL
stephen
"i think MOST roof vents are worthless"
Continuous soffit and ridge vents (with air deflector) is the only passive roof venting system that DOES work.
Gable vents do not. They are exhaust only with no intake. They are dependent on wind speed and direction.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Just trying to solve two conflicting code requirements. When that's the case, it's not likely that any perfect solution will be found.
If I could figure out a way to close a ridge vent tight, I'd suggest using soffit vents with a ridge vent system. That's a better way to prevent ice dams which is of concern in many colder climates.
I'd do away with the venting requirement by using spray foam. If I remember correctly it doesn't take that much to the underside of the roof sheathing to create a semi insulated space that then doesn't need to be vented. Run it by the building department to see what the requirements are.
When working near Fort Collins I was shocked that the building department had something like 175 formal modifications to the code as written and many more unwritten modifications.
Good luck
Beer was created so carpenters wouldn't rule the world.
Find out what the "exception" means.
704A.2 Attic Ventilation.
704A.2.1 General. When required by Chapter 15, roof and attic vents shall resist
intrusion of flame and embers into the attic area of the structure, or shall be protected
by corrosion resistant, non-combustible wire mesh with ¼ inch (6 mm) openings
equivalent.
704A.2.2 Eave or Cornice Vents. Vents shall not be installed in eaves and cornices.
Exception: Eave and cornice vents may be used provided they resist
intrusion of flame and burning embers into the attic area of the structure.
From what you posted, it would seem like they were saying that a fine screen such as used in a spark arrester or fire arrester might be acceptable if properly installed.
Maybe. Check with your fire marshall.
Take a look at Cor-a-vent's product called "In-vent". This link might get you there.
http://coravent.blogspot.com/2007/03/new-product-in-vent.html