Assuming the insurance payout from the fire and the sale of the property occurred in the same tax year, you can treat it as a single sale, where you sold the structure to the insurance company for the payout amount, and sold the land to another for whatever they paid you for it. Just remember, you still have to recapture and pay tax on all depreciation taken up to the date it was no longer occupied and in service. (The date of the fire.)
It's also perfectly possible that you will have a gain on the sale. it just depends on the numbers.
