If you’re a homeowner and notice a drone hovering around your house, don’t assume it’s one of the neighbors playing with a new toy. It could be your homeowners insurance company doing a little spying to see if your house and property meet all the policy requirements.

Insurance companies across the United States are using drones to take aerial images of homes and avoid insuring high-risk homes, The Wall Street Journal reported. According to that report, “nearly every building in the country is being photographed, often without the owner’s knowledge.”

In addition to drones, insurers are using manned airplanes and high-altitude balloons to photograph properties. The Geospatial Insurance Consortium, a group funded by the insurance industry, has an airplane imagery program that it claims covers 99% of the U.S. population, the WSJ reported.

United Policyholders, a nonprofit group that works on behalf of insurance consumers, noted in an April blog that certain U.S. home insurance companies are using drone surveillance to decide whether to insure homes. In some cases, this has led to insurers denying coverage due to perceived structural issues.

The new tactic is seen as a way to eliminate high-risk policies, according to United Policyholders, and it has angered both customers and even some insurance company employees.

“We’ve seen a dramatic increase across the country in reports from consumers who’ve been dropped by their insurers on the basis of an aerial image,” Amy Bach, executive director of United Policyholders, told the WSJ.

The insurance industry counters that drones and surveillance planes help them respond faster to disasters and allow them to charge rates that better reflect a property’s risk.

“If your roof is 20 years old and one hailstorm is going to take it off, you should pay more than somebody with a brand-new roof,” Allstate CEO Tom Wilson told the WSJ.

In any case, drones and aerial photos are likely here to stay, despite consumer pushback. Here are four things insurance companies look for with drone images and how they could cost you money.

1. Roof problems: This is one of the most common things that insurers look for when taking aerial photos. Often, they will spot something as simple as discoloration or streaking to determine a roof’s condition. In some cases, you will need to spend money to repair or replace the roof — which typically costs anywhere from $6,000 to $13,000 or more — or find another insurer.
2. Overhanging trees and tree limbs: These are considered a major insurance risk, which means you will need to pay for the trees to be trimmed or removed. A tree removal can cost roughly $200 to $2,000, according to Angi.
3. Undeclared trampolines: Trampolines are deemed a threat to physical safety and are not typically included in standard home insurance policies, according to American Family Insurance. If a drone captures an undeclared trampoline, you will either need to remove it or contact a third-party insurer and pay for a trampoline insurance policy.
4. Excessive yard debris: As with trampolines, yards with excessive debris are considered a safety hazard that increases the insurer’s liability. If you are contacted because a drone took footage of debris in your yard, you will either need to pay to have it removed or risk losing your insurance coverage.