How Long Does Commercial Construction Take? Real Timelines From Lease to Keys
The 2026 Block Renovation planning guide puts a small office under 5,000 square feet at about 3 to 5 months for design, permits, and construction combined, and a mid-size office at 4 to 8 months. Ground-up runs much longer: roughly 4 to 6 months for a small retail building, 8 to 18 months for an office building, and 12 to 24 months or more for a large industrial facility. The number everyone underestimates is the permit: in Portland, the city aims to finish a first review in 10 days for a tenant improvement and 20 days for new construction, and every round of corrections adds a re-review on top. Here is where all that time actually goes, and which parts you can compress.
Real timelines from our own jobs: the 5,618 square foot Orenco Family Medicine clinic in Hillsboro ran September 2025 to January 2026. The 3,790 square foot Thirsty Caterpillar bookstore and cafe in Lake Oswego ran 2025 to 2026, and the 4-story building at 2465 NE Alberta in Portland ran 2023 to August 2026. Call (360) 326-2747 for a timeline on your space.
| Project type | Typical timeline |
|---|---|
| Small office TI under 5,000 sq ft, design through construction (Block Renovation, 2026) | 3 to 5 months |
| Mid-size office TI, 5,000 to 20,000 sq ft (Block Renovation, 2026) | 4 to 8 months |
| TI construction phase alone (Block Renovation, 2026) | 6 to 24+ weeks |
| Medical build-out, design through construction (Keyser, 2025) | 20 to 30 weeks |
| Small retail building, ground-up | 4 to 6 months |
| Office building, ground-up | 8 to 18 months |
| Large warehouse or industrial, ground-up | 12 to 24+ months |
| Portland permit review, alteration or TI (city goal for first review) | 10 days |
| Portland permit review, new construction (city goal for first review) | 20 days |
TI rows from Block Renovation (2026) and Keyser (2025), ground-up rows from VDBG, and Portland review times from Portland Permitting & Development (all sources below). Every project is its own case; treat these as planning numbers, not promises.
We build tenant improvements and ground-up commercial projects across Portland and Southwest Washington, and the honest answer to "how long will it take" is that three separate clocks are running: design, permitting, and construction. Most schedule pain comes from treating the first two as afterthoughts.
The three clocks, and which one you are underestimating
Design takes 4 to 10 weeks of space planning and drawings in Block Renovation's 2026 guide. Permitting in Portland: the city's goal for a first review is 10 days for an alteration and 20 days for new construction, plus 5 to 7 days for each re-review after corrections. Construction for most tenant improvements runs 4 to 16 weeks for most projects per Mastt (2025), and Block Renovation's 2026 range stretches to 24 weeks or more as scope grows.
Notice what that means: on a typical project, the drawing and approval time rivals the building time. Tenants who sign a lease, then start design, then wait on permits, burn months of rent before a wall moves. The projects that open on time run these clocks in parallel instead: design starts during site selection, and long-lead materials get ordered while the permit is still in review.
How long does a tenant improvement take?
The 2026 Block Renovation guide puts a small office under 5,000 square feet at 3 to 5 months from design through construction, and a mid-size office of 5,000 to 20,000 square feet at 4 to 8 months. Other published guides run shorter: Keyser (2025) puts office TI work at 12 to 20 weeks for design, permitting, and construction combined, with warehouse spaces at 16 to 24 weeks and retail at 10 to 16, and tells tenants to plan on 8 to 12 weeks from lease execution to occupancy; Mastt (2025) says most TI projects take 4 to 16 weeks depending on size and scope.
The outliers are specialized spaces. Keyser (2025) puts medical build-outs at 20 to 30 weeks for design, permitting, and construction, citing code compliance, sterilization systems, and specialty equipment. If that is your project, the details live in our dental and medical office design guide. Restaurants carry similar friction: hood systems, grease interceptors, and health department sign-off.
The Portland permit clock, specifically
Permit timing is the piece people search for and the piece most guides dodge, so here are the local numbers. Portland Permitting and Development publishes its goals: a first review within 10 days for a commercial alteration and 20 days for additions and new construction, and re-reviews within 5 to 7 days. Structural review of an alteration with seismic upgrades or a valuation of $200,000 or more can take up to 20 working days. The first review ends in approval or a checksheet of corrections, and the city notes the timeframes change with workload. The steps are in our guide to City of Portland commercial building permits. The city now publishes its actual review times on a public dashboard, updated weekly, so you can check the current numbers rather than guessing from old forum posts.
Two things follow from that math. First, the cheapest schedule win on any project is a clean first submission: drawings that anticipate plan-review comments can skip a round of corrections and re-review. Second, who files the application, and with which jurisdiction, matters: the process differs between Portland, Multnomah County, Washington County, and Vancouver WA, and filing wrong costs weeks. That is its own guide: who is responsible for pulling permits.
Plan review is also where fixture counts get checked against your occupant load, so restroom math you skipped early can surface as a correction late. Run the numbers from our commercial bathroom requirements guide before you submit, not after the checksheet comes back.
How long does ground-up construction take?
For new buildings, design-build planning guides put small retail buildings at 4 to 6 months of construction, mid-size office buildings at 8 to 18 months, and large warehouse or industrial facilities at 12 to 24 months or more. Counting land use review, design, and permitting, the full start-to-finish process spans from about six months to over two years. Site conditions move these numbers more than anything else: utilities, grading, and stormwater work can add a season before the slab is even poured.
What actually blows up a schedule
- Design changes after permit submission. Every revision risks another round of corrections and re-review.
- Long-lead items ordered late. Rooftop HVAC units, electrical switchgear, and storefront glazing routinely quote in months. Ordered after permit issuance, they, not the crew, set your finish date.
- Discovering code problems in review instead of design. Occupant load, fixture counts, accessibility clearances: cheap to solve on paper, expensive to solve on a checksheet.
- Waiting for the lease to start everything. The single most common mistake. Design and even permitting can begin before lease execution; rent starts whether your drawings are ready or not.
Have a lease date you are working backwards from? Tell us the space and your target opening and we will tell you honestly whether the calendar works, and what has to start now for it to happen.
Frequently asked questions
How long does commercial construction take?
The 2026 Block Renovation planning guide puts a small office under 5,000 square feet at about 3 to 5 months for design, permits, and construction combined, and a mid-size office at 4 to 8 months. Ground-up construction runs much longer: roughly 4 to 6 months for a small retail building, 8 to 18 months for an office building, and 12 to 24 months or more for a large warehouse or industrial facility.
How long does a tenant improvement build-out take?
The 2026 Block Renovation guide puts a small office under 5,000 square feet at 3 to 5 months and a mid-size office at 4 to 8 months, with 4 to 10 weeks of design, 2 to 12 weeks of permitting and approvals, and 6 to 24 or more weeks of construction. In Portland, the city aims to finish a first review of an alteration in 10 days, plus re-reviews after corrections. Medical spaces run longer: Keyser (2025) puts medical TI at 20 to 30 weeks.
How long do commercial building permits take in Portland?
The Portland Permitting and Development goal for the first review is 10 days for a commercial alteration and 20 days for additions and new construction, with re-reviews in 5 to 7 days, and the city notes these change with workload. The first review ends in either approval or a checksheet of corrections, so the total depends on how complete the first submittal is.
What part of the project takes the longest?
Usually not the construction. Design and permitting together often consume as much calendar time as the build itself, and they are the phases tenants most often underestimate. Starting design before the lease is even signed is the single biggest schedule saver.
How long does it take to build a commercial building from the ground up?
Roughly 4 to 6 months for a small retail building, 8 to 18 months for a mid-size office building, and 12 to 24 months or more for large warehouse and industrial projects. Counting land use review, design, and permitting, the full process spans from about six months to over two years.
Can a commercial construction timeline be shortened?
The compressible parts are the ones before construction: start design during site selection, submit permit-ready drawings that anticipate plan-review comments, and order long-lead items like HVAC units, switchgear, and storefront glass as soon as drawings are far enough along. Clean drawings that avoid extra correction cycles skip re-reviews, and the Portland goal for each re-review is 5 to 7 days.
The bottom line
Commercial construction time is three clocks, not one. The build itself is usually the most predictable of them; design and permitting are where months quietly appear and where they can be quietly saved. Work backwards from your opening date, start the paper phases early, and the calendar becomes something you manage instead of something that happens to you.
Modern Northwest builds tenant improvements and commercial projects across Portland and SW Washington, and scheduling honestly is part of the job. Reach out for a free walkthrough and a real timeline for your space.
Sources
- Portland Permitting & Development, "Check permit status" (review phases and first-review goals)
- Keyser, "How Long Should I Plan for Tenant Improvements (TI) When Leasing Office Space?" (Nov 2025)
- Mastt, "How to Set Up Your Tenant Improvement Construction Schedule" (Dec 2025)
- Block Renovation, "Commercial Interior Renovations Process and Timelines" (Mar 2026)
- VDBG, "Commercial Building Construction Time: Key Factors & Averages"
- Portland Permitting & Development, "Check Permit Timelines" (the live review-time dashboard)
Working backwards from a lease date?
Tell us the space and the target opening and we will give you a real timeline. Reach out for a free consultation.