February 8, 2023

fire resistant roofing

fire resistant roofing

How Homes Ignite

The homes can ignite through three different ways that include embers/firebrands, radiant exposure or direct contact with the flame. A typical example of ignition by embers is when the wind blows burning embers are deposited on materials like a wood shake roof. Untreated wood shakes or roof covering can be the biggest threat to the home.

Roof Coverings & Assemblies

Roof coverings with fire ratings are A B, C, or unrated, with Class A offering the most efficient performance. Common Class A roofing materials comprise asphalt-based fiberglass shingles with concrete, barrel-shaped or flat tiles. Certain materials carry an “by assembly” Class A fire rating. This means that other materials are required between the roof covering and the sheathing in order to obtain the rating. Some roof coverings with an “by assembly” fire rating are aluminum, recycled plastic and rubber, and a few wood shakes that are fire-resistant. If a wooden shake roof doesn’t have the documentation of the manufacturer indicating its fire retardant consider that it is untreated.

Tile and Roof Coverings that have gaps between the Covering and Roof Deck

Tiles that are barrel-shaped or flat metal, cement, and roof coverings may be voids between roofing covering and the sheathing that typically appear on the edges and ridges of roofs. These gaps could allow rodents and birds to build nests using materials that can be easily ignited by sparks. These types of debris that has been ignited can extend into the structural support members, thereby bypassing the protection provided by a Class A-rated roof covering. The process of plugging these gaps between the roof deck and the covering is often referred to as “bird stopping”. Make sure to regularly check and maintain these openings.

Debris Accumulation in Roofs & Gutters

The debris that is blown by the wind (including pine needles and leaves from overhanging and nearby trees) can build up on gutters and roofs. Dry debris may be ignited through embers that are blown from the wind. The flames may extend all the way to the roof as well as adjacent siding. In spite of Class A-flame-rated roof covers the vertical surfaces that are next to the edge of the roof are exposed to flames caused by the incendiary debris. Remove regularly vegetative debris from your gutters and roof.

How Fire-Resistant is Your Roof?

  • The rating for fire protection of a roofing covering is Class A or Class Bor Class C or unrated. Unrated roofs are the most vulnerable. The most typical instance of an unrated roofing covering is one constructed with non-fire retardant treated wood shakes or shingles.
  • Classes A and A are the fire-resistant class and should be the preferred choice for anyone who lives in wildfire-prone zones.
  • Roof coverings of Class A comprise asphalt composite shingles, as well as clay or concrete tiles. Certain materials carry the “by assembly” Class A fire rating, which implies that other materials have to be placed in between the roofing sheathing and the roof cover to achieve that fire ratings. Some roof coverings that come with the “by assembly” fire rating include aluminum, fire-resistant wood shakes, as well as recycled rubber and plastic products.

    • If you own a wood shake roof but do not have, or are unable to locate documents from the manufacturer that lists the fire rating for the shake, then assume that it is unrated.
  • If you’re not certain or would like to verify your roof’s type, you can schedule an inspection of your roof with an experienced roofing expert. How to hire an expert roofer.
  • If your house is in a region that is susceptible to wildfires, and your roof is not rated or is worn out and must be repaired, IBHS recommends that you install a fire-rated Class A roof.

Maintaining Your Roof If Needed, Replace Your Roof Covering

If your roof is at the point of no return in its duration, it needs to be replaced. IBHS suggests hiring a professional roofing company to repair or replace the roof covering.

If you’ve got untreated wooden shake roofing, the best option to lower the risk of wildfire should be replacing it with an certified roofing covering. No matter what your fire risk due to the fact that a variety of Class A roof coverings are readily available, IBHS recommends installing a Class A roof covering for those who live in an area that is prone to wildfires.

The roof’s edge and covering is the most vulnerable parts of a house. Due to its vast and relatively horizontal surface it is the one that has the greatest exposure to elements of all kinds which include rain and sun as well as, during wildfires or a blaze, sparks. Due to these exposures roofing materials tend to require more frequent maintenance and usually have a lower time to service over other building materials that are that are used for the exterior of houses.

Ratings for fire protection on roofs are an indication of the level of protection. Class A provides the best protection, while Class C is the lowest. At a minimum, non-rated roofs, like an untreated shake roof must be replaced with roofing that is rated. Class A roofing is commonly offered and can be inexpensive, which means they could be well worth the price. No matter what type of roof the roof should be maintained in good shape and free of combustible waste. The local fire and building department would be aware of any specific requirements that might apply to your area.

The roofing materials can earn the Class A rating on the cover alone (a separate Class A cover) and the roof covering with an underlying material to improve fire resistance (Class A through assembly). The rating for fire protection of roofing materials is determined using a standard test procedure created through the American Society for Testing and Materials (ASTM) and is known as the Standard Test Method E-108. The test measures the spread of flame across that roof, speed at the fire’s ability to penetrate it (and in the ceiling or attic space) as well as the potential for generating embers from the roofing material. If the spread of flames is too extensive or fire is able to penetrate across the covering as well as other construction materials beneath the roofing material cannot be classified as Class A.

If you are using an assembly-rated Class-A covering be sure that all installation guidelines are followed and all required materials are employed. The performance of the covering could be diminished when installation procedures are altered or if materials that are not specifically specified are used instead.

Certain roofing materials that are non-combustible receive an individual Class A rating for meeting the non-combustible requirements as defined by the code for building. consequently, they don’t require testing against an ASTM E-108 standard and given an fire-resistant rating (e.g. an class A or Class B or Class C fire-resistant classification). One exception to this standard is an aluminum-based covering. Due to its low melting point it is required to be examined. Installation instructions will also include the using an additional layer of material beneath the aluminum covering in order to obtain the class A (by the assembly) rating.

Wood shakes treated with a pressure-impregnated, fire-retardant chemical can achieve a Class A assembly rating. In California wood shakes that are treated with a fire-retardant must undergo a natural weathering exposure test in order to be approved to be used through the Office of the State Fire Marshal (OSFM). Wood shakes that are approved to be used in California have to be registered in the OSFM Building Materials Listing Program. In certain communities inside as well as outside California wood shakes or shingles that have been treated with fire retardants aren’t permitted.

A roof that is complex offers an additional degree of risk. The term”complex” means that there are a variety of vertical-to-horizontal intersections on the roof which can make a Class A roof more susceptible to wildfires particularly an exposure of embers. From a performance standpoint they provide gathering locations for the wind-blown debris (e.g. pine needles, and other plants) as well as the debris of trees that hang over and, during a wildfire, windblown embers. These are also the places in which different building materials with different fire-risks will be on the specific surfaces. If the fire is ignited, the flaming caused by the burning debris will create a flame contact with materials for siding, roof sheathing material or soffit or even windows. The vulnerability of these elements will be determined by the material chosen as well as other factors in the design. Particularly, with the Class A roof, it is the resistance to fire that is present in the sheathing, siding or window that determines the strength of the roofand will not be the roofing covering itself.


Skylights generally cover a smaller part of the roof however, they can provide an entrance point for wildfire. Skylights that are flat contain glass that has been tempered. Domed skylights are made of plastic shell around the outside, typically and an inside layer made of flat glass. Domed skylights can open (i.e. they’re operable) screen is sometimes utilized instead of an outer layer made of flat glass.

If your skylight is operable make sure that it is shut during a wildfire to prevent the entry of glowing and burning embers. The skylights in these designs will not meet the requirements of a Class A test for fire exposure that is used to test roofing materials. To determine the vulnerability of skylights, take into consideration the slope of your roof, the position of nearby combustible materials and the place where you have the accumulation of debris that has accumulated around the skylights. If your roof is of an extremely steep slope the skylight will receive the most radiant energy from surrounding burning buildings or vegetation and glass could crack or break, or the plastic may change shape. Always, it’s recommended to keep all debris out of the way to avoid the view. The majority of the time, debris won’t build up on domed skylights however, it could on flat skylights, in particular on roofs that have lower slopes. Also, debris may accumulate on the outside of skylights. If this debris ignited then the building components and connections at the roof-to-skylight junction could be at risk, which is why it is essential to remove debris regularly. Management of vegetation should be an aspect of your strategy. Tree branches that hang overhanging must be cut off because a damaged branch can cause a skylight to fall and fracture.

Roof Edges

The roof edge is susceptible to wildfires through two different ways. One is when you have a clogged rain gutter that is located close to the edge of your roof. The second is when you have roofing profiles, where the design causes massive gap between roof covers and roof sheathing. One common instance is the barrel-shaped clay tiles. The gaps usually occur near the edge of the roof however, they can also be found at the roof’s the ridge (peak). In both cases, an ember exposure is the main ignition source.

Rain Gutters

If embers ignite and debris, the burning material in the gutter can provide the flame with an exposure to the roof’s edge. The safety that the roof edges provide is required to withstand the introduction to the flames in the attic as well as the cathedral ceiling. The roof edge should also guard against the ignition from the roof sheathing exposed or the fascia board that is exposed. The risk of exposure is greater in the event that the metal angle flashing is not applied at the edge of the roof and the gutter is suspended just below the roof edge leaving roofing sheathing unprotected.

The most crucial thing you can do to your gutter is to clear it of any obstructions. The debris could be easily ignited by embers in an wildfire. The material the gutter is constructed of is not as important. Metal (noncombustible) drain will remain in place, while debris ignites, and the resulting flames be able to penetrate the edges of the roof (not the Class A roof but rather the edge).

The risk of the roof’s edge will depend on the materials employed and the degree to which flashing is installed, which protects the edge. In contrast the plastic (plastic) gutter can quickly melt, break and fall to on the earth (Jennings 2000). The ash that is burning will fall along with it and burn for a long time upon the earth. After it’s on the ground the roof’s edge is not exposed to flames anymore However, combustible siding could be, especially if nearby vegetation or the ground cover quickly catch fire. The issue for gutters is debris that accumulates within the gutters. Clean them of debris and the issue goes out of the way. Cleaning and inspection of any debris that is in the gutters must be carried out prior to the start of the fire season begins and every year afterward. Because debris, like burning embers, may be blown into the area from nearby areas, a proper control of vegetation ( reduced fuel) plan for your property could minimize, but not completely stop the build-up of debris in your gutters. One way to help to reduce the risk of debris accumulation in the gutter is to block the downspouts , and then fill it with water. The downspouts should be cleaned after returning home.

With the many potential issues with gutters, why don’t we eliminate gutters? Gutters that are properly installed and maintained and downspouts perform a crucial function in managing moisture for buildings by capturing and transferring water to areas the point where it won’t create an adverse (moistureassociated) effect on foundations or the crawl space. (A properly-installed drainage system that is subsurface it could reduce the necessity of gutters.)

Many gutter cover products are readily available. They are designed to reduce to the build-up of dirt inside the gutter while allowing the flow of water to be free through them and out. They are either covered with a solid or screen, or cover the gutter with porosity (foam) product. There is a range of cover designs, such as those that) contain screens that completely cover the gutter,) use a solid thin sheet of metal that is able to cover the gutter, but with an opening on the edges to allow water to get in the gutter, or) make use of a hybrid cover and louvered design. The thin, solid metal cover is based on the water’s surface tension and releases the metal edges of the cover and falling in the drain. The porous foam covers allow water to pass through and move through the gutter, without allowing debris to get through the pores. An evaluation procedure for the effectiveness of these devices hasn’t been created yet, so if considering using the one you are considering, you should review the literature available to show various designs and also look at devices in nearby homes. They require regular maintenance, and with some they can cause debris to build up on the roof of devices, something is something you need to take away. There is no way that any of the devices will likely to be maintenance-free.