Monthly lease rates by unit size, what San Francisco Department of Building Inspection (DBI) requires, the Approximately 92-100 mph Vult, but seismic governs engineering that applies here, and the point where buying beats renting. Real numbers for budgeting, not a "call for pricing" page.
Adjusted for this metro. Rate only; delivery, set and site work are separate and listed below.
| 8' x 20' · 160 sf2-3 people · Single office, one desk plus a small table. Fits a tight urban lot. | $305$275/mo on 12 mo · $240/mo on 36 mo |
| 10' x 40' · 400 sf4-6 people · Two-room split with a lavatory option. The most-leased jobsite size. | $535$480/mo on 12 mo · $415/mo on 36 mo |
| 12' x 44' · 528 sf6-8 people · Open bullpen plus a private office. Standard superintendent trailer. | $710$640/mo on 12 mo · $555/mo on 36 mo |
| 24' x 44' double · 1056 sf12-16 people · Doublewide, two entries, restrooms. Project field office for a large GC. | $1,330$1,195/mo on 12 mo · $1,035/mo on 36 mo |
| 24' x 60' double · 1440 sf18-24 people · Conference room, private offices, ADA restroom. Program office. | $1,870$1,685/mo on 12 mo · $1,460/mo on 36 mo |
| 36' x 60' triple · 2160 sf28-36 people · Triple-wide complex. Owner, GC and inspector share one building. | $2,770$2,495/mo on 12 mo · $2,160/mo on 36 mo |
Budgeting estimates based on researched market rates, not binding quotes.
This is where lease budgets break. Every one of these is a real line item.
| Delivery and set (single unit, level site)Truck, pilot car when required, block and level, tie-down. Rises with distance and crane need. | $1,400 - $3,200 |
| Delivery and set (doublewide / triple)Multiple trailers, marriage line seal, crane or forklift set, interior trim-out of the seam. | $3,600 - $9,500 |
| Teardown and return freightMirrors the set cost. Budget it at lease signing, not at the end of the job. | $1,400 - $9,500 |
| Steps, landings and ADA rampWood steps are cheap. A compliant ADA ramp with handrails and a 5 ft landing is not. | $650 - $6,800 |
| Skirting and anchoring packageRequired in most wind zones and by most municipal temporary-use permits. | $900 - $4,200 |
| Utility connection (electrical, water, sewer)The single most variable line. Depends entirely on how far the nearest service point sits. | $1,800 - $14,000 |
| Damage waiver / physical damage coverageStandard on lease paper. You can often substitute your own certificate of insurance. | 8% - 14% of monthly |
Demand here is not driven by office scarcity. It is driven by project siting: infrastructure and transit programs, the Mission Bay life-science and hospital corridor, university and institutional capital projects, seismic retrofit programs, and public-sector modular classroom and services buildings. Wildfire and earthquake response also generate abrupt regional demand for temporary facilities that no office lease can satisfy.
San Francisco is the market where I will tell you plainly that modular is not always the answer. With 35.4% vacancy you can lease finished office space cheaply. Modular wins here when the requirement is to be on a specific site, inside a secure perimeter, or in a location with no office product at all.
Conventional office space in San Francisco asks $60 - $63 per square foot per year (JLL Q1 2025 San Francisco office vacancy and asking rents). A 24' x 44' double modular office of 1056 square feet on a 12-month term runs about $1,195 per month, or $14,340 per year, which works out to roughly $14 per square foot per year including the building itself. Put differently, the annual cost of that modular building buys you about 239 square feet of conventional San Francisco office space at current asking rents. If you need more than that much space for more than three years, conventional space is probably cheaper. If you need less, or you need it at a specific site, or you need it before a landlord can build out a suite, the modular building wins.
San Francisco's office vacancy hit a record 35.4% in Q1 2025 with average asking rents of roughly $60 to $63 per square foot, and IPG reported average asking rates near $67.84 in early 2025. This is the one market of the five where conventional office space is genuinely abundant and negotiable, so a modular building here competes on site control and location rather than on price alone. If you need space at a specific site the office market cannot put you there at any rent.
That comparison is the honest one, and it does not always favor the modular building. What it does favor is control. A conventional lease puts you where the space exists, on the landlord's build-out schedule, with a multi-year term. A modular building puts a working office exactly where the work is, usually inside weeks rather than months, and it leaves when the job leaves.
Authority: San Francisco Department of Building Inspection (DBI), with modular units also subject to California Department of Housing and Community Development (HCD) factory-built housing or commercial modular approval.
Code enforced: 2022 California Building Code (Title 24) with San Francisco amendments.
California is the most involved of these five markets. A commercial modular building carries a state HCD insignia from the factory-built program, and the local jurisdiction reviews the foundation, anchorage, utility connection and accessibility rather than re-reviewing the box. San Francisco DBI issues the site permit and a temporary construction trailer is authorized as a temporary use for the duration of the active permit. Title 24 energy compliance applies and is stricter than any other state here.
Wind is not the controlling load in San Francisco. Seismic is. The Bay Area sits in the highest seismic design categories in the continental United States, and that changes the anchoring, the chassis engineering and the connection details of a modular set. A unit specified for a Gulf Coast wind zone is not automatically compliant here, and vice versa. This is the single most common engineering mistake made when shipping a unit into California from a Southeastern factory.
Bayfront and Mission Bay parcels carry sea-level-rise and liquefaction considerations that drive geotechnical work and foundation design well beyond a normal pier-and-pad set.
| Permitting authority | San Francisco Department of Building Inspection (DBI) |
| Building code edition | 2022 California Building Code (Title 24) with San Francisco amendments |
| Design wind speed | Approximately 92-100 mph Vult, but seismic governs |
| Oversize permit authority | California Department of Transportation (Caltrans) Transportation Permits |
| Freight distance from South Florida | 3,050 miles · about 45 hours |
Run the arithmetic on the 12 x 44 reference unit for this market rather than accepting a rule of thumb.
| Monthly lease rate on a 12-month term | $640/mo |
| 12 months of lease payments | $7,680 |
| 24 months of lease payments | $15,360 |
| 36 months of lease payments | $23,040 |
| Purchase price, new, same unit | $117,600 |
| Purchase price, refurbished | $69,900 |
| Lease months to equal a NEW purchase | 184 months |
| Lease months to equal a REFURBISHED purchase | 109 months |
Lease payments on that unit reach the cost of a refurbished purchase at about 109 months and a new purchase at about 184 months. Under roughly eighteen months, leasing is the right answer for most projects: you carry no resale risk and no maintenance obligation. Past thirty months you are usually paying for the unit twice, and buying leaves you holding an asset that still has resale value when the job ends.
The case for leasing past that crossover is real but narrow. It applies when the project end date is genuinely uncertain, when the unit has to disappear from the balance sheet, or when a single project budget cannot absorb a capital purchase.
This is the longest haul of the five and the one where freight materially changes the budget. I-10 west to I-5 north is the standard route. Caltrans issues the oversize permit, California enforces stricter route, escort and travel-time restrictions than Texas or Florida, and urban San Francisco delivery windows are narrow. For a California project, sourcing from a West Coast factory usually beats shipping from Florida once freight and escort costs are counted honestly.
Before delivery, three things decide whether the set goes smoothly: a level pad with truck access and adequate turning radius, a confirmed utility connection point, and a permit on file. The most common cause of a failed delivery is not the building. It is a site nobody walked first.
Lease agreements in this industry are drafted by the lessor and the default terms favor the lessor. Every item below is negotiable, and asking before you sign costs nothing.
| What is the minimum term, and what does early termination cost? | Most agreements carry a minimum. Ending early usually triggers the balance of the term rather than a flat fee. |
| Is return freight quoted now or at pickup? | Quoted at pickup means market rate on the day, which you cannot budget. Get the number fixed in writing at signing. |
| Can I substitute my own certificate of insurance for the damage waiver? | Usually yes, and it commonly costs less than the waiver percentage applied to the monthly rate. |
| Who services HVAC and appliances during the term? | Should be the lessor on a lease. Confirm the response-time commitment, not just who is responsible. |
| What condition standard applies at return, and what counts as normal wear? | The vaguest clause in most agreements and the most common source of a surprise final invoice. |
| Does the rate escalate on renewal or month-to-month rollover? | Rollover rates are frequently higher than the original term rate. Ask for that number now. |
| Who pulls and pays for the permit? | Varies by supplier. If it falls to you, budget both the fee and the review time. |
| Is the unit engineered for Approximately 92-100 mph Vult, but seismic governs? | Ask for the anchoring and tie-down specification in writing rather than a verbal assurance. |
The two that cost the most money in practice are return freight and the return condition standard. Both are quiet at signing and loud at the end of the job.
Tell us the scope and the ZIP. You get a real delivered-and-installed number, not a "contact us for pricing" runaround.