Austin: 100 Yr. Floodplain - Building Unoccupied Structure

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We purchased (January '21) a newly constructed home located in 78721 that is in the FEMA 500 year floodplain, but based on Atlas 19 is now structured as a 100 Year Flood Plain.

We are looking at designing the backyard and ideally adding a pool with a "pool house". After doing some research and discussing with the city, we have been told we are not allowed to build a building unless it is "unoccupied". We first told the city we wanted to build an "office", but they nixed that and stated unoccupied is only a garage, storage or shed.

What exactly can we build in the backyard that would be considered an unoccupied structure? Ideally we would want a little pool house / office. It would be ideal if we could have water and electricity, but at this point we are just trying to figure out what can be built to qualify as "unoccupied".

This is all based on code 25-7-93 General Exceptions:



A development application with a proposed building or parking area that encroaches on the 100-year floodplain may be approved if the encroachment is:


a parking area that is smaller than 5,000 square feet or an unoccupied structure that has an area of less than 1,000 square feet, and the director determines that the proposed development:


will not have an adverse effect on the 100-year floodplain or surrounding properties; and


otherwise complies with the requirements of this title;

Not a lawyer, and I didn't stay at a Holiday Inn Express last night, but we have friends who did something similar. As I understand it, after the structure is approved and built you can modify it however you see fit. So you could build an external garage, and then after the fact choose to setup an office in there. Again, not a lawyer, so do you due diligence.