Katy requires a building permit for converting a garage to living space under the 2021 IRC and 2023 NEC adopted Jan 1, 2024. Conversions cannot create an unrelated rental unit, and HOA deed restrictions in master-planned subdivisions often prohibit the change.
The City of Katy adopted the 2021 International Building Codes (including the 2021 IRC) and the 2023 National Electrical Code effective January 1, 2024, codified in Chapter 3 (Building Regulations) of the Code of Ordinances. Converting an attached garage into conditioned living space is a change of use that triggers a residential building permit through the Permits and Building Services Department at 901 Avenue C (281-391-4830), with separate trade permits for any electrical, plumbing, or mechanical work. The IRC requires the new space to meet habitable-room standards: minimum ceiling height, emergency egress windows in any sleeping room, smoke and carbon monoxide alarms, insulation in walls, ceiling, and floor, a permanent heating and cooling source, and ventilation. The exterior garage door opening must typically be infilled with framing matching the wall assembly. Under Katy's Zoning Ordinance Exhibit 14A, an Accessory Dwelling Unit may only be used by family members, guests, or employees working within the principal residence; commercial use including separate-apartment rental is prohibited, so a converted garage cannot legally be rented to an unrelated tenant. Master-planned communities throughout Katy (Cinco Ranch, Cane Island, Falcon Ranch, Elyson, Firethorne) impose deed restrictions and architectural review requirements that frequently prohibit garage conversions outright; HOA approval should be obtained before applying for a city permit. Properties in Katy's ETJ in unincorporated Harris, Fort Bend, or Waller County follow county and state rules instead of city zoning, but still need a county building permit where applicable.
Unpermitted garage conversions are a frequent code-enforcement issue that surfaces at resale, appraisal, or inspection. Code Enforcement can require restoration of the original garage, retroactive permitting with full inspections, or removal of unpermitted electrical, plumbing, and HVAC work. Renting a converted garage as a separate unit violates the ADU definition in the Zoning Ordinance and may trigger zoning citations as well as building-code action.
See how other cities in Fort Bend County handle garage conversions.
See how Katy's garage conversions rules stack up against other locations.
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