Most homeowners understand that their home’s roof is an important part of the residence, providing both protection from the elements and helping to maintain a stable temperature. Unfortunately though, many homeowners underestimate the importance of making sure they have fireproof roof materials.
Understanding fireproof roof and safety helps you make good decisions to protect your home.
Why is fire safety an important?
Your roof is a large exposed area, high above the ground, possibly containing a few antennas.
This leaves is prone to accidents and acts of nature.
Depending on where you live, wildfires are a real possibility.
Embers travel far with the wind and can easily spark a fire.
Even if you’re in no danger of wildfires, there are other possibilities to be aware of, especially during the summer. Some common circumstances include the following:
- Lightening strikes
- Chimney sparks
- Bonfire or barbeque embers
- Sparks from a nearby house fire
What does it mean to have a fireproof roof?
The terms fireproof roof materials and fire resistant materials can be used interchangeably to describe how easily a material burns.
All materials, including those used for roofing, are categorized according to their relative fire resistance.
The independent safety and certification company Underwriters Laboratories, Inc. also known as UL, created standardized categories, or rating, to describe a material’s flammability.
In order to receive a rating, the manufacturer must submit its material for testing.
Having such a rating system helps customers easily distinguish the safety of all fireproof roof materials available to them.
The tests look at three characteristics:
- How the flame penetrates through the outside roof material and into the underlying attic,
- How the flames spread over the roof’s surface
- The degree that the roof material forms embers
The fireproof ratings are referred to as Class A through Class C. Below they’re described in order of increased flammability.
Class A is the highest rating a material can earn. These are the least flammable materials.
A flame will spread no more than 6 feet; it can withstand a brand measuring one square foot and weighing 2,000 grams; last 2 to 4 hours before igniting; and it can resist igniting through 15 cycles of having a gas flame turned on and off.
Class B materials were effective against moderate surface fire.
A flame will spread no more than 8 feet; it can withstand a brand measuring six square inches and weighing 500 grams; last an hour before igniting; and it can resist igniting through 8 cycles of having a gas flame turned on and off.
Class C materials were effective against light surface fire, and are the most flammable.
A flame will spread no more than 13 feet; it can withstand a brand measuring one and a half square inches and weighing a quarter of a gram; last 20 minutes before igniting; and it can resist igniting through 3 cycles of having a gas flame turned on and off.
How safe are common roofing materials?
If your roof was built or repaired by a reputable contractor then you’re in good shape as far as fire safety.
Contractors have to follow strict rules concerning the materials and techniques they’re allowed to use.
Those rules take fire safety into account.
The most fire-safe materials include fiberglass-based asphalt shingles, clay and slate tiles, and concrete tiles.
Pressure treated shingles are less safe. Unsafe materials include plywood, and untreated wood shingles.
Some common fireproof roof materials are described in more detail below:
Fiberglass-based asphalt shingles
Asphalt shingles are by far the most economical and most commonly used roofing materials.
Some estimates note they’re used on about 80% of homes within the U.S.
The exterior of your roof looks like normal asphalt shingles, which are fire resistant on their own.
When combined with a fiberglass underlayment the structure becomes even more resistant to fire, earning a Class A rating.
This roof covering is durable and can last several decades requiring little maintenance.
Care should be taken during heavy winds to make sure no shingles blow off; any bare spots make the roof vulnerable to fire and water damage.
Clay tiles have proven to be one of the safest roof coverings available.
Clay inherently resists flames and easily dissipates heat. When properly installed they achieve a Class A fire safety rating.
Though more expensive to install than asphalt, homeowners largely find that clay tiles are still affordable.
They’re also extremely durable and can last up to thirty years.
Thanks to modern manufacturing methods clay tiles are available in a number of colors to match any decor.
Slate, like clay, is a natural material and inherently resistant to fire. It’s been used for centuries to line fireplace hearths.
When properly installed it achieves a Class A fire rating.
It’s important to recognize that slate roofing tile is different than other slate tiles, like the ones used for flooring.
Slate used for roofing is thicker and heavier than other tiles.
That thickness is part of what helps it achieve its Class A rating because it’s not easily chipped where fire can penetrate through.
Slate is a more expensive roofing material, but it’s been known to last nearly a hundred years.
The slate roofs of many historic homes have survived over 70 years, without the benefit of modern construction techniques.
And since it’s heavier than other roofing materials you need to make sure your framing is strong enough to support it.
Pressure-treated wood shingles
Wood shingles offer unsurpassed style and warmth but pose more of a fire risk than other materials.
Achieving good fireproof roof safety depends on how the roof is installed and maintained.
A roof that hasn’t been well maintained may be brittle and have empty exposed areas.
Also, wood roofs usually require regular sealing to maintain its effectiveness against fire.
Your home’s roof is a big investment and serves many important functions.
Although homeowners are largely familiar with other roofing maintenance requirements, most aren’t knowledgeable about the risk of fire, and the importance of fireproof roof materials.
Summer is an especially likely time to be concerned with fire.
Understanding your risk, the basics of fire safety, and the different types of fireproof roof materials will ultimately help you have a safe fun summer in your home.
Common Questions About Fire Resistance
Wildfires, lightening strikes, fireworks, chimney sparks, bonfire or barbecue embers, sparks from a nearby house fire.
Class A ratings are the least flammable; a flame will spread no more than 6 ft. Class B ratings are effective against moderate surface fire, and flames will spread no more than 8 ft. Class C materials are effective against light surface fire and are the most flammable; a flame will spread roughly 13 ft.
Fire rating classifications are based on: how the flame penetrates through the outside roof into the attic, how the flames spread over the roof’s surface, and the degree that the roof material forms embers.
Fiberglass asphalt shingles (Class A), clay tiles (Class A), slate tiles (Class A), pressure-treated wood shingles (Class A).