Insurance companies will pay damage to your property based on a depreciated amount. For instance, if you have a roof with a 20 year lifespan in a storm destroys it when it's 10 years old your insurance company will only pay you 50% of the value of the roof.
Sounds reasonable. It rarely is. If your property is well-maintained your depreciation is probably a fraction of what your insurance company wants to charge you. Also, insurance companies depreciate things such as demolition, debris removal and furniture moving on a regular basis. These are services which cannot be depreciated.
If you have a property loss, carefully review your insurance companies estimate of damages. Challenge any depreciation you think is unfair. Insurance companies save millions of dollars by wrongfully depreciating just about everything. Remember, never except the first estimate, always challenge the insurance companies numbers and, if the company cannot prove its numbers, don't take no for an answer. A little bit of knowledge goes a long way.