What Are Tenant Improvements? A Complete Guide for Business Owners and Property Managers

Modern Northwest · Published August 10, 2026

Tenant improvements are the permanent construction changes made inside a leased commercial space so a business can actually use it. Walls, flooring, ceilings, lighting, HVAC distribution, plumbing, and the finishes that go with them. You will also hear them called TI, tenant build-out, tenant fit-out, or leasehold improvements. They all describe the same thing: the work between a bare or outdated space and one your business can open in.

Most explanations of tenant improvements are written by brokers or accountants, so they stop at the lease. This one is written by the general contractor who does the building, which means it covers what the work actually involves, who is responsible for what, and where the schedule really goes.

What counts as a tenant improvement, and what does not

The dividing line is permanence. If it stays with the building when you move out, it is generally a tenant improvement. If it leaves on a truck with you, it is not.

Specialised equipment sits in a grey zone and is worth settling in writing early. A restaurant exhaust hood, a walk-in cooler, a dental vacuum system, or a lead-lined imaging room may be treated as a tenant improvement if it stays with the building, or as your equipment if it does not. Different landlords answer this differently.

Tenant improvements, capital improvements, and building shell

Three terms get used interchangeably and should not be. Knowing which one you are talking about tells you who pays.

• Building shell. The structure itself: foundation, frame, roof, exterior walls, and the utilities brought to the space. The landlord owns and delivers this. A cold shell has almost nothing inside; a warm shell may include basic HVAC, restrooms, and a finished ceiling.
• Tenant improvements. Everything built inside that shell to suit one specific tenant. This is the layer this guide is about.
• Capital improvements. Work on the building as a whole that outlives any single tenant, like a roof replacement, a new elevator, or a parking lot rebuild. These are the landlord's, and they are not funded out of your allowance.

Accountants will call your completed tenant improvements leasehold improvements, and treat them as a depreciable asset. Same work, different vocabulary depending on who is in the room.

Who is responsible for what

There is no universal answer, only what the lease says. That said, the most common commercial arrangement splits like this:

• The landlord delivers the shell in an agreed condition and contributes money toward the build-out, usually as a per-square-foot tenant improvement allowance.
• The tenant decides the layout and finishes, hires the architect and general contractor, and pays for anything above the allowance.
• Both sign off on the drawings before construction, because the landlord has to live with the result after you leave.

The exception is a turn-key deal, where the landlord builds to an agreed plan and pays the contractors directly. Less work for you, and less control over the outcome. How much the landlord actually contributes, and how you negotiate for more, is a whole subject of its own, covered in our guide to tenant improvement allowances.

How a tenant improvement project actually runs

Five stages, and the middle one is the one that surprises people.

• 1. Space assessment, before you sign. Walk the space with a contractor while the lease is still negotiable. This is the cheapest hour in the whole project, and it is the only point where you can still change the deal if the space needs more work than it looks like it does.
• 2. Design and drawings. An architect turns your layout into permit-ready construction documents. Mechanical, electrical, and plumbing engineering happens here too.
• 3. Permitting. The jurisdiction reviews the drawings. This is normally the longest unknown in the schedule and it is largely outside anyone's control, which is why it belongs in the plan rather than as a surprise. See who is responsible for pulling permits.
• 4. Construction. Demolition, framing, mechanical and electrical rough-in, inspections, then finishes.
• 5. Final inspection and occupancy. The jurisdiction signs off, your equipment vendors install, and you open.

For real timelines by project type, including where the months actually go, see our commercial construction timeline guide.

What tenant improvements look like by space type

The phrase covers wildly different amounts of work depending on what you are opening. A second-generation office that already has walls in roughly the right places is a different project from an empty shell becoming a dental practice.

• Office. Usually the lightest. Offices, conference rooms, a break room, and updated finishes. Sizing guidance is in our office space planning guide.
• Medical and dental. Heavy on plumbing, electrical, and mechanical. Operatories each need their own services, imaging rooms need shielding, and sterilisation areas need specific surfaces and airflow. Detail in our dental and medical office design guide.
• Restaurant. Typically the most involved. Kitchen ventilation, grease interceptors, health department review, and far more plumbing than any other use.
• Retail. Storefront, sales floor lighting, fitting rooms, and back-of-house. ADA clearances drive much of the layout.
• Industrial and flex. Often a modest office area built inside a much larger warehouse shell.

Tenant improvements in Portland and SW Washington

Locally, two things drive a tenant improvement schedule more than anything else: which jurisdiction reviews the permit, and how finished the space already is. A build-out in Portland, Beaverton, and Vancouver, WA can follow three different review paths for the same set of drawings, and each city has its own queue.

Modern Northwest has been building commercial interiors across the Pacific Northwest since 2008. We plan, permit, and build tenant improvements for offices, medical and dental clinics, retail, and restaurants throughout Oregon and Washington.

Frequently asked questions

The bottom line

Tenant improvements are the work that turns a leased shell into a space your business can open in, and the single best thing you can do is get a contractor into the space before the lease is signed. That one walkthrough tells you what the build-out really involves, whether the landlord's allowance covers it, and how long the permit is likely to take.

Modern Northwest is a commercial general contractor in Portland building tenant improvements across Oregon and SW Washington. Reach out for a free walkthrough and estimate before you sign.