Tax assessments are usually not reliable estimates of fair market value. If you restored the property to as-was condition, you can use the cost of the restoration as an acceptable estimate of the loss in FMV. If you did not restore the property, or you improved it to better-than-before condition, the repair cost is not a fair estimate of the loss in value and you may need to see a real estate professional for an appraisal.
For second home, explain more about rented. How many days a year do you use the rental home for personal use (including by you or other members of your family or friends you don't charge rent to) and how many days of the year do you rent it out?
The normal casualty loss procedure applies only to personal property. Business property losses are reported differently. The answer of how to deal with the second home will depend on whether it is personal, business, or mixed, and how much.