4864 form

1. To determine the fair market value before and after: ask your local realtor, city tax assessment, neighborhood sales- what would the value be if I had put it on the market the day before the storm?

Next, determine what the value was the day after the storm. Depending on the damage, sometimes just the cost to fix something is all it takes but sometimes there is a bigger picture and almost nobody would want to buy and fix it. Again a realtor may be able to help or the estimates you received. Keep a record of how you came up with the values.

The casualty deduction is the lower of your basis = cost + improvements over the years or the change in fair market value. 

Don't forget a fence or plants may have been damaged as well. Other things that you paid for and may have blown away.

2. The IRS has  Publication 584, Casualty, Disaster, and Theft Loss Workbook (Personal-Use Property) to help you with the appliances and furnishings.

References:

FAQs for disaster victims

See the FEMA website to search for specific disasters