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Part of Tenant improvements as a construction project hidden inside a lease
Seven layers make up tenant improvements rules for 2027: here is how a reviewer reads them
Tenant improvements rules explained as seven layers, plus how to find which code edition your own address adopted and what your lease adds on top of that.
There is no single rulebook for fitting out a space. There are several, they are written by different bodies, they are adopted at different times by different governments, and the versions that apply to your job are decided by your address. This page explains the layers and how to find out which edition of each one governs your work.
Nothing here states a requirement as current fact. That would be worthless to you, because the answer changes across a state line and sometimes across a city boundary. What is stable is the structure, and knowing the structure is what lets you ask a useful question.
What to take away
- Model codes are written by private bodies and only become law when a state or a municipality adopts a specific edition, often with local amendments.
- Federal accessibility duties run in parallel with local construction review and are not discharged by passing an inspection.
- Your lease adds a private rulebook on top of all of it, and that one is negotiable while the others are not.
The layers, in the order a reviewer meets them
1. Land use. Whether your activity is allowed at that address at all, at those hours, with whatever you keep outside. This is decided locally and separately, and how to get the answer is in zoning and permits.
Seven layers a reviewer checks
- Land useis your activity allowed here
- Constructionstructure, egress, fire, plumbing, mechanical, electrical
- Fire and life safetyfire code and fire official
- Accessibilitypublic space requirements
- Energyefficiency rules for the work
- Existing buildingwhat the building was approved under
- Leaseprivate rules on top of code
2. Construction. How the work must be built: structure, means of egress, fire resistance, plumbing, mechanical and electrical. Most jurisdictions in the United States build this layer from a model code family published as the I-Codes, and the building volume itself is readable online as the International Building Code. The published edition is not the rule. The rule is whichever edition your state or municipality has adopted, plus its amendments.
3. Fire and life safety. Sometimes handled inside the construction code, sometimes by a separate fire code, sometimes by both with a fire official who has the final word on your building. Two documents commonly referenced are the Life Safety Code and the sprinkler installation standard NFPA 13. Whether either applies to you depends on adoption, and on what the building was originally approved under.
4. Accessibility. For space used by the public this is a federal obligation that exists whether or not a local inspector mentions it. Its scope is described under ADA Title III and its design requirements are published separately. Passing a local plan review does not settle it.
5. Energy. Insulation, glazing, lighting and controls are governed by an energy code adopted the same way as the construction code. What it requires of a fit-out varies with how much of the space you are touching.
6. Environmental and health. Old materials, waste, discharges to drain, and food handling each bring their own office. These are the layers most likely to surprise a fit-out in an older building.
7. The private layer. The lease, the work letter and the building rules. These bind you contractually and can be stricter than any public rule. Unlike the public layers, they are negotiable, and only before signing.
How to find the version that applies to you
- Ask the building department which code editions the jurisdiction has adopted, and whether there are local amendments. Ask in writing.
- Ask the same question of the fire authority, because the fire code is often adopted separately and sometimes at a different edition.
- Ask what triggers a full upgrade. Many jurisdictions treat a small alteration differently from a change of use or a large renovation, and the trigger is the thing that decides your budget.
- Ask what the building was originally approved under and what has been altered since. Unrecorded work by a previous occupier becomes your problem when your application is reviewed.
- Ask your designer to confirm, in writing, which documents they are designing to.
Two thresholds come up most often. The first is area: a work area above 50 percent of the building's floor area or replacement value can turn a fit-out into a whole building upgrade. The second is a change of use, which is a separate trigger and often the stricter one.
The 50 percent figure is typical, not universal. Your building department sets its own threshold.
Keep every answer. A file of dated written replies is the difference between a disagreement you can settle and one you cannot.
Find your adopted code edition
- Ask building department which editions adopted
- Ask fire authority which fire code edition
- Ask what triggers a full upgrade
- Ask what building was originally approved under
- Ask designer to confirm documents in writing
What changes, and what does not
Model codes are revised on a cycle. Adoption lags revision by a variable and sometimes long period.
Here is the cycle in dates. The International Codes are revised every three years: 2018, 2021, 2024 and 2027. The 2024 editions were published in 2023.
The 2027 editions are scheduled to follow the same pattern, which points to publication in 2026 and the first state adoptions in 2027 or later.
California runs its own three-year cycle. Its 2025 Building Standards Code is scheduled to take effect on January 1, 2026, so a permit pulled there in 2027 sits under that edition rather than the 2022 one.
So two things are true at once: the published edition moves, and the edition governing your address may not have moved for years.
What does not change is the shape of the questions. Every fit-out has to answer how people get out, how the space is ventilated, how it is powered, whether everyone can use it, and what happens to old materials that are disturbed.
Where the private rulebook bites hardest
The lease layer produces most of the delays that feel like regulation but are not.
- The approval period for your drawings, and what silence at the end of it means.
- Which contractors the landlord will accept.
- Insurance certificates naming the parties the lease names, at the limits it sets.
- Working hours, access, lifts and waste.
- What has to be removed at the end, and who decides.
A typical work letter gives the landlord 10 business days to review drawings. Many add that approval is deemed granted if the landlord does not respond in that window, and a typical window is 5 to 15 business days.
On insurance, $1,000,000 per occurrence and $2,000,000 in the aggregate is a common floor for commercial general liability. Clauses usually name the landlord and its lender as additional insureds and require the cover to be primary and non-contributory.
Those limits are typical ranges, not fixed. The lease you sign sets the binding number.
All five are negotiable while the lease is in draft. None of them is negotiable afterwards. The commercial terms surrounding them are in commercial leasing, and the money mechanics of a landlord contribution are in tenant improvements.
A short reading list for your own address
| Question | Who answers it | Ask for | Where to find it |
|---|---|---|---|
| Is my use allowed here? | Planning or zoning office | The district, the use table entry, and any conditions | The zoning map and use table on the city planning site, plus the certificate of occupancy |
| Which construction code edition applies? | Building department | Edition adopted, date, local amendments | The state or city code adoption page and the administrative chapter of the adopted code |
| Which fire code applies? | Fire authority | Edition adopted, plus anything specific to this building | The fire marshal page for the jurisdiction and the building's fire permit file |
| What triggers a full upgrade? | Building department | The threshold, in writing | The existing building chapter of the adopted code and the department's plan review handouts |
| What was this space approved as? | Building department records | The last approved plans and sign-off | A records request for the permit file, and the certificate of occupancy |
| What does the lease require? | Your property lawyer | The work letter read against the lease | The full lease, its amendments and the work letter exhibit |
Common questions
Can I just design to the latest published code?
You can, and it is sometimes the safer choice, but it is not automatically compliant and it may be more expensive than your jurisdiction requires. Confirm the adopted edition first.
The landlord says the work is exempt from permits. Is that reliable?
It is an opinion from an interested party. The permit office is the only body whose answer protects you, and asking costs nothing.
Does an inspection sign-off mean I have met the accessibility obligations?
Not necessarily. Federal accessibility duties for businesses open to the public exist independently of local plan review, which is why the design stage is where they belong.
Who should hold all this in a small business?
One named person, with a folder. The designer, the contractor and the landlord all have partial views and none of them carries your risk. If the job is complex, the base building questions in office space and the trading-unit sequence in retail space are the right places to start assembling it.
