You've signed the lease. Now you're hearing two opposite things. A friend who opened a café says you'll need an architect. The first contractor who walked the space says not to worry, they handle the plans. For a lot of commercial tenant improvements, neither answer is quite right.
California doesn't decide who has to design your build-out based on what kind of business you run. It decides based on what the work changes. Move a wall that sits on an exit route, hang a heavier ceiling, add a hood, or turn an office into a dental suite, and the list of design jobs grows. Keep the work to finishes and fixtures, and it can shrink to almost nothing. Your real decision isn't "architect or contractor." It's which design jobs your scope creates, and who is responsible for each one.
Do you need an architect for a commercial tenant improvement?
Not always. California's Architects Practice Act exempts certain interior work from the requirement for a licensed architect: nonstructural or nonseismic storefronts, interior alterations, fixtures, cabinetwork, furniture, appliances and equipment, plus the work needed to install them. That exemption is in Business and Professions Code §5538.
The exemption comes with a condition. The alterations can't change or affect the building's structural system or its safety. A tenant improvement (TI) that only replaces flooring, paint, lighting fixtures and casework in a space that already works can sit comfortably inside it. A TI that moves exits, alters fire-rated walls or adds structural load usually can't.
The building official makes the final call on whether your specific scope fits the exemption. The statute sets the boundary. Your city's plan checker applies it to your drawings.
What turns a simple interior job into one that needs licensed design?
The trigger is whether the work affects safety, not whether a load-bearing wall moves. A partition can be non-load-bearing and still change how people get out of the building, how the sprinklers cover the room, or whether the ceiling stays up in an earthquake.
These are the conditions that most often take a TI outside the architects' exemption:
- Changed exits. New walls or doors that alter the path people take to leave the space.
- A change of occupancy. A new business isn't automatically a new code occupancy. When the use, occupant load or hazard level does change, the code analysis changes with it.
- Fire-rated construction. Work on rated corridors, rated walls or separations between tenants.
- Structural changes. New openings in bearing walls, altered framing, or equipment the existing structure has to carry.
- Seismic bracing. The City of Sacramento's commercial TI checklist, revised March 2026, asks for anchorage details on suspended ceilings and partitions and cites the ASCE 7-22 structural standard.
- Rooftop equipment. Elk Grove's TI requirements ask for the weight and anchorage of rooftop equipment, and engineered calculations when structure is modified.
In the Sacramento region, published guidance generally expects stamped professional plans and treats the unlicensed route as narrow. The Sacramento Metropolitan Fire District's plan requirements call for an architect's or engineer's stamp, with an exception for certain single-exit business and retail interiors without rated separations. Roseville's April 2026 TI checklist asks for stamped and signed plans plus structural, energy and accessibility documentation where they apply.
If you don't need an architect, who can draw your plans?
Three kinds of providers can prepare plans for exempt TI work, and each has a limit. Which one fits depends on what's in your scope, not on which title sounds more qualified.
An interior designer
An interior designer can prepare plans for exempt interior work in California, whether or not they're certified. Certification isn't required to offer interior design services. A California Certified Interior Designer (CID) can stamp and submit qualifying interior documents. Those documents have to be identified as interior design documents, not architectural or engineering documents. The CID commercial designation is a training credential. The certifying council says it doesn't expand what a CID is legally allowed to design, and it doesn't guarantee a city will accept the plans.
An engineer
A licensed civil, electrical or mechanical engineer can design within the discipline they're licensed and competent in. An engineer can sometimes supply the structural or systems portion of a TI instead of an architect. That doesn't make every engineer the right person to design an entire suite. California engineering rules restrict licensees to fields in which they're actually competent.
A contractor
A licensed contractor can prepare shop and field drawings and design certain systems, within limits set by statute. Those limits are tighter than most owners expect, and the next section covers them.
Can your contractor design the electrical and mechanical systems?
Yes, but only for systems the contractor's own crews will install. Under Business and Professions Code §6737.3, a licensed contractor can design electrical or mechanical systems for work performed and supervised by that contractor, within the classification on its license. The statute says plainly that this doesn't extend to designing work that someone else installs. The state engineering board's guide for local officials reads it as covering installation by the contractor's own employees, not work subcontracted to a different contractor.
So "the contractor handles the plans" tells you very little on its own. The useful questions are narrower. Who designed this system? Whose crew is installing it? Is that the same company, licensed in that trade?
The same goes for the word "design-build." A general building license (Class B) authorizes a contractor to take on multi-trade building work. It doesn't authorize the contractor to practice architecture or structural engineering. When a contractor-led firm provides architectural services, California's architects' board requires a licensed architect to be in responsible control while the drawings are being prepared. A stamp added after someone else finished the design doesn't meet that standard. A firm can genuinely do design and construction under one roof. You confirm it by asking who the licensed people are and what they're responsible for, not by reading the firm's name.
Which engineers does your scope call for?
The ones your actual changes trigger. No statute requires a separate engineer for every discipline on every TI. A need for engineering arises when the work creates a technical question nobody on the team is licensed and competent to answer.
Structural
Structural design comes in when you alter framing, cut openings in bearing walls, add equipment the building has to carry, or need anchorage for ceilings, partitions or rooftop units. In California, civil engineering includes structural work. A competent civil engineer can handle many ordinary TI structural tasks. Unusual existing structures and heavy equipment loads make the case for a more specialized structural engineer.
Mechanical and heating, ventilation and air conditioning (HVAC)
Mechanical design comes in when you change air distribution, add or replace rooftop equipment, or install a kitchen hood with exhaust and makeup air. A trade contractor designing a simple system its own crew installs may be enough. Whole-suite air balancing, unusual exhaust, or several connections to existing building systems make the case for a mechanical engineer. If you're taking over a restaurant space, it's worth asking first whether the existing HVAC can actually run your restaurant.
Electrical
Electrical design comes in when you add circuits, lighting or equipment. Local TI checklists ask for load calculations, panel and circuit information, and equipment connections. The engineering job goes beyond placing outlets. It's confirming that your equipment loads will actually fit the power coming into the space.
Plumbing
Plumbing design comes in when you reroute water, waste or gas lines, add fixtures, or size a water heater. "Plumbing engineer" is a common job title, but California doesn't license plumbing as its own engineering branch. Under the state engineering act, plumbing falls within mechanical engineering.
Fire sprinklers
Fire sprinkler design comes in when your new layout changes how the existing sprinkler heads cover the space. San Francisco's fire department accepts sprinkler submittals from either a qualifying engineer or a licensed fire protection contractor (C-16). The City of Sacramento's 2026 TI checklist asks for fire system documentation. If no change is needed, it asks for a letter from a C-16 contractor stating the existing systems won't be negatively affected. Fire systems are usually submitted separately from the building plans. An architect's drawing set doesn't automatically include the sprinkler calculations.
Do you need a Certified Access Specialist (CASp)?
Not for every tenant improvement. A Certified Access Specialist (CASp) is most useful when the hard question is whether the building's existing entrance, restrooms, counters or route to your suite meet accessibility rules. Architects and engineers can evaluate accessibility without being a CASp. A CASp adds an independent check of what's already there.
Two limits are worth knowing. According to the state's Division of the State Architect, a CASp reviewing your plans doesn't by itself give you the legal protections tied to a CASp inspection. Those protections require a qualifying inspection and report. And a CASp inspection certificate records that an inspection happened. It doesn't certify that the building complies. Who decides what accessibility work your permit requires is a separate question, covered in who pays for ADA upgrades outside your commercial suite.
What changes for a restaurant tenant improvement?
Your menu decides how much design work a restaurant needs. Sacramento County Environmental Management (EMD) reviews food facilities when the food types, preparation methods, service style or equipment change, even if the physical remodel is modest. A second-generation restaurant space doesn't prove your menu fits the systems already there.
EMD's current food facility checklist asks for detailed information that someone has to work out:
- Hood drawings, specifications and calculations, makeup air, and an air balance schedule where its conditions apply
- Water heater size and recovery rate
- Hot and cold water lines, floor sinks and drains, and whether each piece of equipment connects to waste directly or indirectly
- An equipment schedule that matches the layout
Food review documents don't require an architect's or engineer's signature. They do require plans complete enough that an incomplete set can't finish review. In practice, that takes someone who can design to that level of detail. Hood fire suppression is a separate design job. The Sacramento Metropolitan Fire District lists kitchen hood extinguishing systems as their own submittal, apart from the building plans. For a sense of what a compact food-service layout involves, see this grab-and-go coffee shop conversion in San Francisco.
What changes for a medical or dental office tenant improvement?
Start with how the facility is classified, not with the word "medical." California's Health and Safety Code §1206 excludes qualifying offices owned or leased and operated by practitioners from the clinic licensing chapter, with stated exceptions. The state's health facility agency (HCAI) applies its OSHPD 3 building requirements only to specified licensed clinics and hospital outpatient services. An ordinary physician's or dentist's office isn't automatically held to licensed-clinic rules.
Specific services add specific design work:
- X-ray and imaging rooms. California Dental Association guidance recommends that a qualified expert develop the radiation shielding for each facility. That's a separate job from general layout, and an architect, equipment vendor or general contractor doesn't replace it.
- Dental wastewater. Roseville's April 2026 TI checklist includes a dental One Time Compliance Report, or an exemption form where it applies.
- Equipment loads. Dental and medical equipment can create electrical, plumbing and ventilation work that an office-style layout never had to account for.
A finish-and-furniture update in an established professional office can still fall within the exemption. The medical or dental label doesn't remove the exemption, and it doesn't prove the exemption applies.
Will hiring more professionals slow your tenant improvement down?
Not because of the number of people. What slows a tenant improvement down is work nobody owns, and two people with authority over the same decision.
Research on the question points in both directions. A study of one large design project found that design iterations increased as more participants and outside suppliers got involved, and decreased where the team did integrative work together. Construction Industry Institute research found that weak coordination between design disciplines and design rework were closely related to rework in the field.
Skipping a needed function doesn't save time either. Sacramento County EMD says food facility review can't be completed without the required information. The City of Sacramento's preparer guidance returns unclear or insufficient plans for completion. Leaving the mechanical calculations out of a restaurant submittal doesn't make them go away. It moves the question to plan check, or to the field after the ceiling is closed.
The practical test isn't headcount. It's whether every technical question on your project has one named person responsible for answering it.
How is this different in Bay Area cities?
The state rules are the same across California, but each city publishes its own screen for when it wants licensed plans. A tenant improvement that clears one city's screen won't necessarily clear another's.
- San José updated its guidance on plans requiring an architect or engineer on March 2, 2026. It lists occupancy and exit changes, rated assemblies, structural or safety effects, and certain partition and ceiling conditions as triggers. It allows limited nonstructural commercial exceptions and keeps the building official's discretion.
- San Francisco's Department of Building Inspection information sheet G-01 allows certain one-floor, non-high-rise commercial TIs to qualify as exempt, subject to several conditions. It also lets the city require licensed plans where state law wouldn't. The sheet is dated 2018, so confirm its thresholds against current code before relying on it.
- Oakland's commercial TI permit page doesn't publish a TI-specific stamp threshold. Restaurant and bar projects need Alameda County Environmental Health approval before Oakland issues the building permit.
Your lease can narrow your choices further. Some work letters require a landlord-approved architect and landlord-approved engineers for structural, mechanical, electrical, plumbing and fire work, even where state law would let you use someone else. Check what your lease already decided about your build-out before you hire anyone.
What should you ask whoever is drawing your plans?
Ask who is responsible for each design job your scope creates, by name and license. These six questions get you there:
- Which design jobs does my scope trigger? Exits, occupancy, structure, ceiling bracing, mechanical, electrical, plumbing, fire, accessibility, health review.
- Who is the licensed or certified person responsible for each one? A firm name isn't an answer. California requires an architect's contract to describe the services and identify the license.
- Is the person designing each system also the one installing it? If a contractor is designing electrical or mechanical work, its own crew has to be doing the installation.
- Who owns each handoff? The ceiling layout and the sprinkler coverage. The hood and the rooftop unit. The equipment list and the electrical panel.
- Are site visits and testing included? Under §5536.25, an architect who stamps the drawings doesn't automatically take on a duty to observe construction. California's energy code requires acceptance testing of mechanical systems and lighting controls before final inspection, by qualified technicians where applicable. Hiring a designer doesn't automatically cover either.
- What insurance actually covers the design work? A license isn't proof of insurance. The state engineering board's guide says engineers aren't legally required to carry liability insurance, and the architects' board recommends asking architects directly. General liability isn't the same as professional liability coverage.
This process moves fastest when you can hand over a written description of how you'll use the space, your equipment list with electrical ratings, your headcount and hours, and one person who makes decisions. With those in hand, we can walk the space, sort out which of these jobs your scope triggers, and carry the findings straight into the drawings we submit for your tenant improvement permit.
