Insulation that isn’t fire-rated increases the amount of time a fire can burn and can release smoke and toxic fumes. There are many codes and standards related to insulation and fire safety.
Depending on the material, insulation can be naturally fireproof or non-combustible or treated to prevent flammability. Your local TruTeam can provide recommendations and installation services that meet state and fire codes for insulation.
Fiberglass
Fiberglass is an extremely popular insulation material for a good reason. It offers high R-values at a low cost, making it affordable for homeowners to install in their homes. The material is composed of tiny glass fibers that are tightly packed together to slow down the transfer of heat. As a result, it improves energy efficiency in the home and helps reduce electricity costs.
However, many homeowners have concerns about fiberglass’s fire safety. Some people believe that it’s not as fire resistant as other insulation materials such as rock wool and cellulose. Fortunately, these concerns are unfounded. In fact, fiberglass is an excellent insulator when it comes to fire resistance.
It takes a very long time for fiberglass to melt or burn, even at incredibly high temperatures. In fact, in a recent fire demonstration, it took the ceiling of a building insulated with fiberglass 20 minutes to collapse. In the same time frame, it took the ceiling of a building that was insulated with cellulose less than two hours to burn down.
In addition to being non-flammable, fiberglass has a high R-value at a lower cost than other types of insulation. As with other insulating materials, it’s important to follow insulation standards and regulations to maximize fire safety in the home.
Mineral Wool
Similar in function to fiberglass loose-fill insulation, mineral wool is a non-combustible and fire-retardant alternative that can be installed in new construction and existing homes. It’s made from rock fibers that are spun and woven into blankets or shaped into boards. It’s often used in walls, floors and ceilings to reduce noise transmission and create a more comfortable home environment. It’s typically a better option than fiberglass for insulating areas near furnaces and heat ducts.
Johns Manville CladStone Mineral Wool batts are made from inorganic fibers sourced from basalt, a volcanic rock material. The insulation is moisture repellent, will not mildew or support corrosion and is inorganic to prevent mold growth. It’s also fire retardant and meets UL CLASS A rating to slow the spread of flames and smoke between rooms or floors.
The thermal stability of mineral wool means that the material can be used in walls, floors and ceilings to improve the acoustics of a home. It is a more sustainable choice than fiberglass for insulating older homes that are being renovated.
When it comes to reducing the risk of fire, however, mineral wool may not be the best option. During manufacturing, it requires high temperatures that must be maintained for extended periods of time. This results in an embodied energy footprint higher than other insulation options. In addition, the organic content of the rock material can increase the risk of smouldering combustion and subsequent heat release.
Cellulose
Cellulose insulation is a dense material that is typically blown as loose-fill in attics and wet-sprayed into walls in new construction. It is made from 75-85% recycled paper fiber, and is treated with a fire retardant. It is an eco-friendly choice, as it depletes giant piles of old newspapers thrown away every day. It is also more effective than fiberglass insulation, with a higher R-value.
In a recent Yestermorrow Building Science course I had the pleasure of hosting Bill Hulstrunk, a cellulose insulation installer from UltraCell Insulation in Niagara Falls, NY. His company produces a wet process for their product that they claim leaves it less prone to airborne dust and is less toxic than the dry blown version.
Fire safety is a key concern for the insulation industry. Because cellulose burns at a lower temperature than fiberglass, it can retain heat and smolder for hours after fire is extinguished. These embers can either spread the fire or reignite it at a later time.
The high R-value of cellulose also makes it difficult for flames to travel through the material. This provides an extra measure of protection from fire and smoke compared to fiberglass insulation, which has not been tested for this property. However, this insulation is not completely fire safe, and it is important to follow local and national fire safety codes.
Other Materials
Fiberglass is one of the most common insulation materials in use today. It is made up of extremely fine glass fibers that are spun into batts or rolls. Fiberglass is naturally noncombustible, and it does not require any additional fire-retardant chemical treatment. Unfaced fiberglass is an acceptable fire block when installed in wood frames, although it should always be installed with a code-approved barrier such as foil or kraft paper.
Some loose-fill insulation products such as cellulose, fiberglass and mineral (rock or slag) wool are infused with flame retardants to make them less likely to ignite and burn. These chemicals don’t render the insulation fireproof, but they do delay ignition to provide more time for occupants to escape a burning building.
Rigid foam boards are noncombustible and can be faced with a variety of materials, including foils that reflect radiant heat away from living spaces. These systems offer higher energy efficiency and are less prone to settling over time than blown-in attic insulation.
While no insulation is completely fireproof, the thicker an insulation is the more difficult it is to melt or burn. It also takes longer for a fire to reach the insulating material, which reduces heat flow and prevents damage from excessive thermal shock. Fire endurance testing is performed to determine how quickly a material can withstand a fire, and the time-temperature curves for various insulation materials are comparable.