What's not to love about sandwich panels? Incredibly energy-efficient, sandwich panels have been around for decades and used to construct walls, ceilings and roofs. Still growing in popularity, the sandwich panel market is expected to reach $3.25 billion by 2027, up from $1.46 billion in 2020, according to Market Research Future.

Sandwich panels are made of two layers of metal (usually steel or aluminum), with a thick piece of insulation wedged in between. Commercially, they're commonly used in buildings throughout the food and pharmaceutical industries as well as in cold storage warehouses. And residentially, the Better Business Bureau says that plenty of homeowners are immersed in home renovation projects right now, which means that even if you don't know it, you just might be building a home with sandwich panels.

While they are inexpensive, excellent insulators, lightweight and easy to install, sandwich panels can easily become a major construction hazard, especially when the insulation used in them is combustible. Here's what you need to know so that you can better understand the risks and learn what questions to ask your contractor or builder so that they can be used safely.

Why are sandwich panels problematic?

If the insulation used in a sandwich panel is combustible, the risk of fire increases exponentially. In fact, fires in buildings with sandwich panels made of combustible products are often are so tough for firefighters to extinguish that they usually result in complete destruction of the building. That's because the combustible products add additional heat, large amounts of smoke and toxic gas to the fire.

These common insulation materials are used in sandwich panels and ranked on their level of combustibility (from best to worst):

• Glass fiber or mineral wool (non-combustible)

While fiberglass insulation is noncombustible, it's not nearly as fire resistant as mineral wool, which can even be used as a fire-stop. Both materials are affordable and easy to install.

• Polyurethane or polyisocyanurate (combustible)

Thermal insulation provided by polyurethane and polyisocyanurate foams can result in rapid heat buildup in the event of a fire and may contribute to its rapid spread. Polyurethane and polyisocyanurate can catch fire in a range of 650 degrees Fahrenheit to 1,000 degrees Fahrenheit and release a thick, black smoke when they burn.

• Fiberglass reinforced plastic (FRP) or glass-reinforced polyester resin (combustible)

FRP is a composite material made of a polymer matrix reinforced with other materials such as glass and carbon. It's used in construction, often in the aerospace industry. FRP also ignites in a range of 650 degrees to 1,000 degrees Fahrenheit, releases sooty smoke when burning and can quickly melt and flow, providing fuel to the existing fire.

• Expanded polystyrene or polyethylene (highly combustible)

Both polystyrene and polyethylene start to soften and melt at just 200 degrees Fahrenheit and therefore pose a huge fire risk.

How can builders mitigate these construction hazards?

• Use sandwich panels with non-combustible insulation. Doing so can help minimize smoke contamination, which is especially crucial in commercial buildings that demand quality control, such as food processing and pharmaceutical plants. Using non-combustible materials on interior walls can also provide a protective layer of compartmentalization.
• Don't engage in dangerous work close to walls. Do it far away to avoid accidental sources of ignition such as welding, cooking, forklift battery recharging and spray painting.
• Enclose all electrical passing through the walls and ceilings in metal. Make sure that all sandwich panels are properly sealed and that there is no exposed combustible insulation.
• Leave wide aisle spaces between storage and sandwich paneled walls. Make sure there is adequate separation between heat producing equipment, such as ovens, furnaces and HVAC units.
• Do not store combustible materials along the outside walls of a building.
• Prohibit smoking inside buildings with combustible sandwich panels.
• Ensure you have adequate sprinkler protection throughout your home, as mandated by guidelines from the National Fire Protection Association, and make sure your fire extinguishers are working. (You can hire a professional to make sure the extinguisher is operating safely.)

While sandwich panels have plenty of perks, such as inexpensive insulation that's easy to install, panels that use combustible materials pose a high risk for serious damage in the event of a fire. That's why, when possible, it's important to talk to your builder or contractor about what materials are being used so that you can be informed about the risks of sandwich panels.

If there's an accident, the good news is that your homeowners policy will pay to repair or rebuild your home if it is damaged or destroyed by fire. If you haven't reviewed your policy in a while, now might be the time. For commercial operations, property insurance will protect you in the event that your building and possessions are damaged in a fire.

There's a lot to think about when it comes to keeping your business or home safe. Connect with a Westfield agent today so we can help you make the right decisions for your residential or commercial property and protect what matters to you most.