Two tenants sign leases in the same building, on the same floor, for the same 8,000 square feet. Both want a standard open-plan office with six private offices and a break room. One spends $55 per square foot. The other spends $110.
Nothing about the design explains the gap. What explains it is the condition of the space on the day they got the keys.
What does office tenant improvement cost per square foot in 2026?
Office tenant improvement costs run from roughly $40 to $480 per square foot in 2026, with most standard office build-outs landing between $50 and $175. Basic build-outs with standard finishes run $50 to $100 per square foot. Mid-range with upgraded finishes and custom millwork runs $100 to $175. High-end space with premium materials and sophisticated MEP runs $175 to $300 and above.
That range is wide because two variables move independently: what you are building, and what you are building into. Most cost guides only address the first.
The shell condition spectrum
Shell condition describes how much of the base building work the landlord has already completed. It is the single largest driver of tenant improvement cost, and it varies more than finish level does.
The terminology is inconsistent across markets, which does not help. The same condition might be called a cold shell in one city, a grey shell in another, and a dark shell in a third. What matters is what is physically present.
| Shell condition | Also called | What’s already there | Typical tenant cost / sq ft |
|---|---|---|---|
| Cold dark shell | Grey shell, dark shell | Bare structure and envelope. No HVAC distribution, no electrical distribution, no plumbing, frequently no restroom | $60 – $130 |
| Cold shell | — | Structure, envelope, utilities brought to the space but not distributed. Restroom may exist | $50 – $100 |
| Warm shell | White shell | HVAC distributed, electrical panel and distribution, restroom complete, unfinished walls and ceiling | $30 – $75 |
| Vanilla shell | Warm vanilla shell | Finished walls and ceiling, lighting installed, HVAC operating, flooring in place, working restroom | $20 – $60 |
The gap between the ends of that spectrum is substantial. Published data puts the same use type at 30% to 50% more expensive in a cold dark shell than in a vanilla shell, and build-out costs for a vanilla shell running 40% to 60% lower overall.
Concretely: a cold dark shell means you are paying for the restroom, the HVAC trunk lines and distribution, the electrical panel and every circuit, the ceiling grid, and the entire lighting package before you spend a dollar on anything a visitor would notice.
Why a bigger allowance can leave you worse off
Tenant improvement allowances in 2026 range from about $10 to $100 per square foot, depending on market, lease term, tenant credit, and shell condition.
Here is the part that catches tenants out. The allowance and the cost move in the same direction — but not at the same rate.
Landlords offering cold shell space typically offer larger allowances, often $20 to $60 per square foot. Landlords offering vanilla shell space offer smaller allowances, frequently $10 to $25 per square foot. That looks like the market pricing the difference fairly. It usually is not.
| Cold dark shell | Vanilla shell | |
|---|---|---|
| Landlord allowance | $45 / sq ft | $18 / sq ft |
| Actual build-out cost | $95 / sq ft | $42 / sq ft |
| Tenant out of pocket | $50 / sq ft | $24 / sq ft |
The cold shell deal offers more than twice the allowance and still costs the tenant twice as much out of pocket. The larger number is doing the work of appearing generous.
Two rules follow from this. First, never compare lease deals on allowance alone — compare on net out-of-pocket after a real cost estimate. Second, get that estimate before signing, not after. Once the lease is executed, the shell condition is a fact rather than a negotiating point.
Base building deficiencies: what you inherit that doesn’t work
Shell condition describes what is present. Base building deficiency describes what is present but inadequate.
This is where TI budgets quietly break, because the drawings show what the space will be, not what the base building can actually support. Common ones:
HVAC capacity. The existing system was sized for the previous tenant’s density and use. A tenant putting more people, more equipment, or a server room into the same footprint may need supplemental cooling — and on an older building, the roof may not have the structural capacity or the space for it.
Electrical service. The panel serving the suite has a finite capacity. A tenant with heavy IT load, a commercial kitchen, or specialty equipment can exceed it, which means a new feeder from the main service. On a multi-story building that is an expensive, disruptive scope with no visible result.
Restroom compliance. An existing restroom built to an earlier code may not meet current accessibility requirements. Triggering a renovation can require bringing it fully into compliance — a scope most tenants never budgeted for.
Ceiling height and structure. Existing ductwork, structure, and sprinkler mains may sit lower than the design assumes. Exposed-ceiling designs frequently collide with reality once the tiles come down.
Fire and life safety. Changing the partition layout changes the sprinkler head layout, and sometimes the alarm device layout with it. In a rated corridor, changing an opening can trigger firestopping and door assembly work.
Deficiencies are the strongest argument for having the space estimated before the lease is signed. A landlord who knows their HVAC is undersized may still lease the space as-is and let the tenant discover it. That conversation goes very differently before signature than after.
Finish level tiers
With shell condition and base building settled, finish level takes over as the main driver.
| Tier | Range / sq ft | What it typically includes |
|---|---|---|
| Basic | $50 – $100 | Building-standard carpet and paint, ACT ceiling, standard 2×4 lighting, minimal millwork, standard doors and hardware |
| Mid-range | $100 – $175 | Upgraded flooring including LVT and carpet tile, some exposed ceiling, upgraded lighting, custom reception millwork, glass fronts on offices |
| High-end | $175 – $300+ | Stone and specialty flooring, feature ceilings, architectural lighting, extensive millwork, full-height glass partitions, integrated AV |
The reason finish level is less decisive than people assume: structure, envelope and core MEP are constrained by code and function, so they cannot vary much. Finishes have no ceiling. Moving from building-standard to high-end can add 30% to 50% to a fit-out without changing a single structural member — but it cannot save you from a cold dark shell.
Class A, B and C: what the label actually predicts
Building class describes market position, not construction cost, and tenants routinely over-read it.
Class A buildings typically deliver space in better condition — a finished core, distributed HVAC, a compliant restroom — which lowers TI cost per square foot. They also carry higher base rent and stricter landlord design standards, which can force finish levels above what the tenant would otherwise choose.
Class B is the widest band and the least predictable. Shell condition varies enormously depending on how recently the space was occupied and what the previous tenant left behind.
Class C and older conversions frequently offer the lowest rent and the highest TI cost. Base building deficiencies are common, accessibility upgrades are more likely to trigger, and existing conditions are rarely documented. A 1970s building converted from another use can require more work than fitting out a raw shell in a new tower.
The practical takeaway: building class predicts rent reliably and TI cost poorly. Price the specific space.
What else moves the number
Demolition of existing improvements. Space that was previously occupied comes with partitions, ceilings, flooring and MEP to remove. That is real cost with nothing to show for it, and it is often absent from early budgets.
Partition density. An open plan with six private offices prices very differently from the same square footage divided into twenty-five. Partitions drive drywall, doors, electrical devices, HVAC zoning and sprinkler head count simultaneously. See drywall estimating for how that scope is measured.
Occupied-building constraints. Freight elevator scheduling, noise restrictions pushing work to nights and weekends, protection of adjacent tenants, and multiple short mobilizations rather than one continuous run. All reduce productivity and none appear on the drawings.
Schedule pressure. A tenant with a lease commencement date and a rent obligation has less flexibility than one who can wait. Compressed schedules cost money.
How to protect yourself
Estimate before you sign. The lease fixes shell condition, allowance, and delivery date. All three are negotiable beforehand and none are afterward.
Get the shell condition defined in writing. Not “cold shell” — an itemized list of what the landlord will deliver. Terminology varies by market and the words alone will not protect you.
Compare deals on net out-of-pocket. Allowance minus estimated cost, not allowance alone.
Budget demolition separately. If the space was occupied, get the removal scope priced as its own line.
Ask what the base building can support before designing to something it cannot.
If a space is under consideration and the numbers need to be real rather than a rule of thumb, we can estimate a tenant improvement scope from a space plan — including the base building items a finish schedule will not show.
What these numbers cannot tell you
They cannot price your suite. Shell condition, base building capacity, and existing conditions are specific to the space. No benchmark captures them.
They exclude furniture and technology. Workstations, seating, AV and IT equipment are typically the tenant’s separate budget, and on a modern office fit-out they can rival the construction cost.
They exclude design fees and permits. Architecture, engineering, and permitting commonly add 8% to 15% on top of construction cost.
They age. At current escalation, a figure is roughly 7% understated after two years.
Related reading: commercial construction cost per square foot by building type · interior finishes estimating · drywall estimating
Sources
- Published US tenant improvement cost data and allowance ranges, 2026
- Commercial shell condition definitions and cost differentials, 2026
- Office build-out cost tiers by finish level, 2026
- Edge Estimates tenant improvement takeoff records, 2026
Update log. Published September 2026. Scheduled for review September 2027.
Closing CTA
Considering a space? Edge Estimates prepares tenant improvement estimates from space plans and lease exhibits, including the base building scope a finish schedule will not show. Send drawings to plans@edgeestimates.us for a fixed-fee quote. More on commercial estimating services.
