Fire Rating System
Any number of sources, including chimney sparks, a brush fire or airborne brands ejected from a nearby
building, can ignite a roof covered with a flammable material. Fire resistance, therefore, is an important safety
consideration and the reason why many local building codes as well as the Federal Housing Administration
require that roofing materials conform to certain standards in this respect. The most widely accepted
standards for fire resistance in building materials are those of Underwriters Laboratories, Inc. This non-profit
organization founded in 1894 devotes to testing and to establishing of fire safety standards.
The 3 tests that determine roofing materials resistance to:
Tests are failed if any portion of the roof:
- to intermittent flame,
- Flame spread and
- ignition from burning brands.
- Blows or falls off the deck as flaming or glowing brands.
- Breaks, slides, cracks or warps to expose the roof deck.
- Allows the roof deck to fall away as glowing particles.
- Allows sustained flaming of the underside of the roof deck.
The results of these tests determine whether the roof is
As of 1994 the State Fire Marshall of California has declared all shakes installed must carry a Class 'C' fire rating
- Class "A": Highest fire-resistance rating for roofing as per ASTM E-108. Indicates roofing is able to
withstand severe exposure to fire originating from sources outside the building.
- Class "B": Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure
to fire originating from sources outside the building.
- Class "C": Fire-resistance rating that indicates roofing materials are able to withstand light exposure to
fire originating from sources outside the building.
or better. Effective July 2008, if the house is in a designated "Wildland-Urban Inteface Fire Area" (which
incorporates 99% of Laguna Beach), then all new roof construction must be a Class A.
Wind Resistance test
Underwriters Laboratories also tests asphalt roofing shingles for performance in high winds. In this test
shingles are applied to a roof deck according to the manufacturer's specifications, sealed under controlled
conditions and subjected to a 63-mph wind for two (2) hours. To be eligible for a UL wind-resistant rating, not a
single tab must lift during the entire two hours.
Aesthetically, the two choices to be made on roofs is
It is important to note that any pitch less than 3 in 12 (3 feet of vertical for every 12 feet of horizontal)
requires a waterproofing that is rated for a flat roof, necessitating a "built-up" or "hot-mopped"
application. Obviously this will drive the cost of an installation and only likely makes sense when there is
a height restriction as a result of a zoning requirement.
When installing a roof, ensure to allow for proper attic venting.
- Wood shingle and wood shake roofs are no longer allowed in California due to fire concerns.
Thatched straw roofs have similar drawbacks.
- Rock surface roofs are popular in some municipalities.
- Asphalt shingles are a cost effective choice and come in many color choices
- Slate, though beautiful, is challenging at best when it comes to fragility
- Ceramic, concrete or clay tiles hold up considerably better although depending on their profile, can
still have breakage issues.
- Metal roofs are coming back into vogue (zinc, copper, and lead have been used historically).
Standing-seam steel roofing is the most popular residential metal roofing today
- Living, sod or green roofs are receiving a lot of attention, although because of weight, thickness,
need to water and maintain, their applicability is still quite limited