Insurance companies take vacancy of buildings very seriously. The experiences with vacant buildings historically have not been good so the rules in this situation are quite stringent. We are talking about properties such as a house, barn or office building. We are not talking about an empty machine shed or grain bin. These are typically empty on a seasonal basis and insurers understand this.
You have to notify your insurance company of a building being vacant immediately. If you do not, it may nullify any coverage on the building. Every insurance company will have different ways of dealing with this situation. Some insurers put a notice on your policy (vacancy permit) of its vacancy status and every 2 or 3 months you have to confirm this again with them in order to keep coverage in place. If it is forgotten and they are not updated of this fact again you are in jeopardy of having any coverage at all. Some companies will contact you regularly (through your broker) for updates.
The level of coverage changes when a building becomes vacant. Typically, you no longer have replacement cost coverage, building collapse, vandalism coverage or water pipe breakage coverage to name a few.
It is always very important to talk to your insurance broker as soon as possible to allow for the most proactive approach to this situation.
Be sure to seek advice and purchase insurance from those who understand your business!