FRT Plywood success (C) Daniel Friedman Fire & Ember Resistant Ridge & Eaves Vents
Products resist entry of fire embers into the roof structure

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Self-closing ridge, soffit & eave vents for fire protection:

This article describes products & research on self-closing soffit & eaves & ridge vents designed to reduce or stop the passage of embers into the roof cavity of a building through the building eaves or ridge during exposure of a building to nearby heat and fire from a forest fire, brush fire, or adjacent building fire.

The building fire shown above is discussed in a separate article on fire retardant treated plywood, live link given at the end of this article.

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Roof Structure Fire Resistance: self-closing ridge & soffit or eave vents

Fire and ember resistant soffit vent, Caruso Hendricks Patent US20080220714A1 at

On 2015-11-24 by Charlie Hart

We lost our home recently to a fire in northern CA and have to rebuild from dirt.

I was told that we might have to install some sort of automatic soffit vent closing system that closes off when it senses heat from a fire.

I've tried looking at the 2013 CA Fire codes and did not see anything like that there. Have you heard of such a thing and if so where can I find more information on it?

This question and reply were posted originally at SOFFIT INTAKE VENT BLOCKED

[Click to enlarge any image] Shown here, a detail from Caruso & Hendricks ember & fire resistant self-closing ridge vent.

On 2015-11-26 by (mod) - fire-stopping soffit vents: automatic soffit vent closing system to protect homes from fires in Northern California?


Indeed there are self-closing eaves vents or soffit vent products that reduce the chances of fire-embers moving up into a building attic through the eaves vents.

These products have been discussed and inventions disclosed since at least the 1970's where the idea was explored as a way to provide fire closure of duct systems (Thwaites 1976).

I searched both google and google scholar to report on patents and products for automatic soffit vent closing mechanism for fire protection.

[Click to enlarge any image] Shown here, excerpts from the Caruso Hendricks Ember and Fire Resistant Vent patent (2007).

Watch out: before buying and installing self-closing eaves vents or soffit vents for fire protection you should check with your local fire inspector for suggestions and to learn what systems are approved were you live.

However there are fire stopping soffit vent strips provided by several manufacturers, of whom the most patents and products I found were provided by Vulcan Technologies.

Soffit vent closing mechanisms are both mechanical (using a combination of a fusible link and a magnetically operated closure) and chemical (for lack of a better word) using products that exude material to close off vent openings when exposed to high temperatures of a nearby fire.

The latter type of soffit intake vent strops have a closing mechanism that works by extruding or exuding material that closes off the soffit vent intake openings when exposed to the high temperatures of a fire.

Watch out: Both of these approaches to avoiding fire spread into a building roof or attic space through the soffit intake vents use a one-time activated method to close the vent opening. If the building survives the fire the vent closure system will need to be replaced.

Here is an example from Vulcan Technologies:

Fire-stopping soffit vents should meet the California Building Code SFM 12-7A of the California Wildland Urban Interface fire code program. Here are excerpts from that code and part of a discussion of the absence of a method of acceptance for special eave vents and a resolution that permits use of a fire-resistant soffit vent from Vulcan Technologies.

Model Building Code Section(s) at Issue: 2007 CBC Section 704A.2 Attic Ventilation:

704A.2.1 General. When required by Chapter 15, roof and attic vents shall resist the intrusion of flame and embers into the attic area of the structure, or shall be protected by corrosion-resistant, noncombustible wire mesh with 1/4-inch (6mm) openings or its 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 the intrusion of flame and
burning embers into the attic area of the structure.

Self-Closing Soffit Vent Products, Technologies, Patents, Research & Standards

Carlson Marusic Magnetically actuated self closing air vent patent at

Fire and ember resistant soffit vent, Caruso Hendricks Patent US20080220714A1 at

Vulcan Technologies fire ember resistant self closing soffit vent strips at

Editor's notes: Combustion Points & Fire Spread Notes for Common Building Exterior Siding or Roofing Materials

Experts describing both ignition temperatures and fire spread have commented on temperatures and fire conditions that help understand the possible role and efficacy of a self-closing soffit or eaves vent or ridge vent on buildings. It appears that while vinyl siding is not as highly flammable as some of our readers fear, its behavior during a fire can be a factor in fire spread.

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