I had a fire in February resulting in the total loss of my barn. The claim is "suvervised" and I need to use the depreciation money to do plumbing and electeical. I signed an avidavit to restore the barn to the same or better condition. Insurance is working off 2006 appraisal value. They are not giving me enough to replace any outbuildings or a run in shed for livestock. I am functioning as a Homeowner GC as the new barn is a modular.
I recommend that you talk to your insurance agent first.
As a rule, casualty insurance is a promise to pay you up to a certain amount of money (the policy limit) in the event of a casualty. If you are not able to replace your building with that much money, then you were underinsured.
In other words, you need to look at the policy to see what the insurance company promised to do in the event of a loss. Then, you compare what they actually did to the policy.
If you think the insurance company is not being fair with you, you may want to look up a local, independent insurance adjuster and have them review the matter.
If you still think you are not being treated fairly, then call an attorney.