(1) A city or town that adopts a building code under this chapter may enforce its building code only within the incorporated limits of the city or town.
(2) A county may adopt a building code under this chapter on a countywide basis unless a city or town within the county has adopted a building code. If a city or town within the county has adopted a building code, then the county may not enforce the county building code in that city or town.
(3) A county, city, or town may contract for the enforcement of its building code.