When trying to determine the required amount of flood insurance coverage, it is necessary to know the value of the building not including land value (so this number can be compared to loan balance(s) and maximum insurance coverages available). Is it acceptable to simply use the amount of hazard insurance on the property to arrive at building value, or is it necessary to look at appraisal or other means of valuation? At a minimum, I don't see how a hazard insurance policy would be adequate when trying to determine the required amount of coverage on a condo.

You should be referring to your appraisal for the value of the improvements.

The lender is required to make a good faith determination of value. As Randy stated, hopefully you can get this from the appraisal. The amount of hazard insurance is a good resource (and a good cross check), but not the only source of value.