In Houston, changing what a commercial space is used for — retail to restaurant, office to clinic, warehouse to church — requires a new Certificate of Occupancy, and if the occupancy classification changes, the city requires approved plans and permits for the new use before the CO is issued. That usually means sealed architectural and MEP drawings showing the space meets current code for the new occupancy. A CO also stops being valid when square footage or occupant load changes, not just the use itself.
First: Does Your Occupancy Classification Actually Change?
Every commercial use maps to an IBC occupancy group: office is B, retail is M, restaurants are A-2, daycares are E or I-4, warehouses are S. Converting a retail suite to a nail salon may stay within the same group; converting it to a restaurant moves it from M to A-2 and changes nearly every code requirement that applies — occupant load, egress, restroom count, ventilation, fire protection. The classification question determines everything downstream, so answer it before you sign a lease. QD Design runs this analysis from a floor plan and the intended use, usually before an owner commits to a space.
What a Change of Occupancy Triggers
When the classification changes, the space must be brought up to the code requirements of the new use. The recurring cost drivers in Houston conversions:
- Egress and occupant load. Assembly uses (restaurants, churches) drive higher occupant loads, which can require more or wider exits than the shell was built with.
- Restroom count. Plumbing fixture counts are set by occupancy and occupant load — a restaurant needs more fixtures than the retail space it replaces.
- Ventilation and HVAC. New uses bring new outdoor-air requirements; food service adds Type I hood exhaust and makeup air under NFPA 96.
- Utility capacity. Kitchens and clinics routinely exceed the electrical service, gas, and grease-waste capacity of the space they move into — the most expensive surprise on the list, and the one to verify before leasing.
- Accessibility. Projects at or above the $50,000 TDLR threshold require registration and Texas Accessibility Standards review; alterations must bring the altered area into TAS compliance.
The Houston Process, Step by Step
1. Code analysis. Confirm the current and proposed occupancy classifications and identify every code gap between them. 2. Design. Produce sealed architectural + MEP drawings for the new use — see our full guide to getting a commercial building permit in Houston. 3. Permit and plan review. Submit through the city’s iPermits portal; each discipline reviews against IBC/IMC/IPC/IFC 2021 and current NEC. 4. Construction and inspections. 5. Occupancy inspection and new CO. Apply for an occupancy compliance inspection; the space must be powered and fully accessible — including attic and roof — on inspection day. The new Certificate of Occupancy is what legally lets you open.
A Real Example
A 6,000 SF tenant space in Tomball combining retail, a butcher counter, and food preparation became an A-2/M mixed occupancy — and drew a 25-comment deficiency notice from the city. QD Design provided architecture, MEP, and TDLR registration and resolved every comment to permit approval: hood and fire suppression, walk-in cooler energy compliance, grease interceptor sizing, and egress corrections. Mixed and changed occupancies are where one coordinated A/E team earns its fee.
Frequently Asked Questions
Do I need a new Certificate of Occupancy if I’m not changing the use?
Sometimes. In Houston a CO stops being valid when occupancy use changes, but also when square footage or occupant load increases or decreases. A new tenant continuing the identical use in an unmodified space generally applies for an occupancy compliance inspection rather than full plan review — confirm your exact case with the Houston Permitting Center.
Can I open while the change-of-use permit is in review?
No. Occupying a space whose classification has changed without an approved permit and new CO risks citations and closure, and it can void insurance coverage. Build the permit timeline into your lease negotiation — rent abatement during permitting is a common ask precisely because of this.
How long does a change of use take in Houston?
Design typically runs 3–5 weeks, city plan review and correction cycles commonly run 8–16 weeks total, and construction depends on scope. The biggest schedule risk is discovering late that the shell lacks capacity — electrical service, grease waste, hood shaft routing — for the new use. A pre-lease code and capacity check costs days and saves months.
Does a change of use always mean bringing the whole building to current code?
No. Generally the requirements attach to the changed area and the systems serving it, though life-safety upgrades can reach further depending on the classification moved to. This is exactly the analysis a design team should give you in writing before you commit to the space.
Converting a Space? Check It Before You Sign
QD Design provides occupancy analysis, sealed architecture + MEP drawings, and plan-review responses for change-of-use projects across the Houston metro. Send us your floor plan and intended use — you’ll get a fee proposal within one business day.