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Windowsills may seem like convenient display spaces in your home, but they can become dangerous fire hazards if you place certain items there. The concentrated sunlight that streams through windows can reach surprisingly high temperatures, especially during peak daylight hours. This intense heat and UV radiation can cause some materials to become dangerously hot and even ignite, turning an innocent decorative choice into a potential disaster that could engulf your entire home.
Because windowsills often go unmonitored for hours at a time, the risk is even greater that a problem would go unnoticed. We spoke to a couple of fire safety experts to understand which common household items to never put on a windowsill to help prevent a tragic accident that could result in injury or property damage.
1. Batteries and Chargers
It can be easy and convenient to set your power charger on a windowsill, but it can also create a fire safety risk. Heat from the sunlight beating through the window creates a less than ideal setting for electrical components. “If the sun hits it, the battery inside can overheat, swell, or even start leaking,” warns Forrest Webber, founder of Fireplace Distributor in Albuquerque, New Mexico. This can ultimately trigger a house fire. “I’ve seen some melt slightly into the paint of the sill—not something you want in your house.”
Another issue with setting batteries and chargers on a windowsill is that any water that leaks into the house from the window could destroy the batteries. Excess moisture can lead to corrosion and other damage, so store batteries in a dry area with little to no humidity.
Webber recommends charging electronics on a stable surface like a countertop or table that has plenty of shade and airflow. Avoid leaving them any place where heat builds up.
2. Aerosol Cans
Aerosol cans like hairspray and air freshener also don’t belong on a windowsill. “Spray cans left on a sunny sill can overheat fast, and when the pressure builds up inside, they can actually pop. It’s rare, but it does happen—especially in summer,” explains Webber. Nobody wants an explosive can filled with flammable chemicals causing a huge mess, not to mention a serious fire hazard. Additionally, when these items are exposed to temperature and humidity fluctuations common on a windowsill, their quality can diminish and they can lose their effectiveness.
Webber recommends always storing aerosol cans somewhere cool and shaded, like in a drawer under the sink or a bathroom cabinet.
3. Candles
While it may seem obvious to keep candles away from windows, some people enjoy the look they get from lining up these calming décor items on a windowsill in the kitchen or bedroom. But if you do this, you might need to keep a fire extinguisher nearby. One of the main reasons to keep candles off windowsills is that the curtains or shades can easily catch fire from the candle flame, says Brett Trainham, captain of St. Michael’s College Fire and Rescue at St. Michael’s College in Colchester, Vermont.
In addition, the heat from the sun can warm up the candle or glass jar it’s sitting in, causing the wax to pool and ignite even if the candle isn’t lit, adds Webber. If it gets hot enough, the container can even crack, causing the hot wax to leak all over the windowsill. Airflow from an open or drafty window can also be a recipe for disaster, literally fanning the flame.
In keeping with candle safety guidelines, Trainham advises that lit candles sit on a flat, stable surface in an open space without fabrics around, like the middle of a coffee table with nothing overhead. And when storing candles, choose a cool, dry spot in your home that is away from direct sunlight and other heat sources.
