Washington writes one building code for all 39 counties, and that code contains a section named after your container. Placement is a separate question that every city answers for itself.
Shipping container permits in Washington are two separate permissions, granted by two different counters, and the people who run into trouble almost always answered one question and skipped the other.
The first question is a building code question: does this box need a building permit and inspections? Washington answers that at the state level. RCW 19.27.031 provides that, except as otherwise provided in the chapter, "there shall be in effect in all counties and cities the state building code," and it then adopts the International Building Code, the International Residential Code, the International Mechanical Code, the International Fire Code, portions of the International Wildland Urban Interface Code and the Uniform Plumbing Code by reference. The 2021 editions took effect statewide on March 15, 2024. The 2024 editions are still in rulemaking at the State Building Code Council and are not in effect, so confirm the edition on the Council's rulemaking page before you design to one.
Washington does let local governments adjust that code, which is different from some states. RCW 19.27.040 authorizes the governing body of each county or city to amend the state building code within its own jurisdiction, and then sets the limit that matters: "The minimum performance standards of the codes and the objectives enumerated in RCW 19.27.020 shall not be diminished by any county or city amendments." A Washington city can ask for more than the state code. It cannot ask for less. Seattle takes full advantage of that and publishes its own amended Seattle Building Code.
The second question is a zoning question: is a container an allowed thing to put on this particular lot, in this district, in this position? The state does not answer that at all. Your city or county does, and the answers genuinely differ. Tacoma has written standards specifically naming shipping containers. Seattle regulates by project type and square footage rather than by material. Spokane County publishes a plain permit exemption list. One box, three different conversations.
The numbers that decide the building permit question. A standard 20ft container has a 160 square foot footprint (8ft by 20ft). A 40ft container is 320 square feet. Washington permit exemptions for small detached accessory structures commonly land at 120 or 200 square feet, so those two footprints are the arithmetic to carry into the call.
In practice that means a 20ft box used for dry storage often falls under a county exemption and above a city one, and a 40ft box is above every common exemption in the state.
This is the most useful thing to know about containers in Washington, and it rarely appears in national guidance.
The 2021 International Building Code added Section 3115, Intermodal Shipping Containers, a chapter-length set of provisions written specifically for containers repurposed as buildings. Washington adopts the 2021 IBC under chapter 51-50 WAC, and the state's amendments to Chapter 31 do not touch Section 3115, so it applies here as published. Seattle, which writes its own amendments, prints the section in full in the 2021 Seattle Building Code, Chapter 31. Section 3115.1 sets the scope:
"The provisions of Section 3115 and other applicable sections of this code shall apply to intermodal shipping containers that are repurposed for use as buildings or structures, or as a part of buildings or structures."
That is good news, not bad news. Before 2021 a plan reviewer looking at a container had to reason by analogy. Now there is a written path. Section 3115.3 asks that the container bear its existing ISO 6346 data plate, verified by an approved agency, carrying the manufacturer identification, date manufactured, safety approval number, identification number, maximum operating gross mass, allowable stacking load, transverse racking test force and valid maintenance examination date. Section 3115.4 covers protection of the wood floor against decay and termites, 3115.5 covers under-floor ventilation, 3115.6 covers roof assemblies and 3115.8 covers the structural design.
The practical takeaway for a permit conversation: ask the container be identified by its data plate, and keep that plate legible until the inspector has seen it. It is the cheapest piece of documentation in the whole project. Our companion guide on container homes in Washington walks through the structural side of Section 3115 in detail, including the simplified design path and the four limitations that come with it.
Seattle publishes its rules by project type rather than by material, so the useful question in Seattle is not "how does the code treat containers" but "what am I building, and how big is it."
The Seattle Department of Construction and Inspections sets out a no-permit path for small storage buildings. Per SDCI's shed guidance, you do not need a permit when all of the following hold: "The total area (or 'footprint') of the shed's roof is 120 square feet or less," the shed is a single-story building, it "sits on a simple concrete slab, pier blocks, or soil," it is not attached to a house or other building, it is not in or near an environmentally critical area, and "The shed is only used for storage, growing plants, or similar generally unoccupied uses." Height is capped at 12 feet.
Run the arithmetic. A 20ft container is 160 square feet, so it is above Seattle's no-permit line before you have discussed anything else. Most sheds over that threshold take a subject-to-field-inspection permit, which skips formal plan review and verifies compliance by inspection instead. A full construction permit is required in an environmentally critical area, over 750 square feet, or where beams span more than 14 feet.
That environmentally critical area clause is a real Seattle condition rather than fine print. Seattle maps steep slopes, landslide-prone areas, liquefaction-prone areas, wetlands and riparian corridors, and being inside one removes the small-project shortcuts. Ask about it with your address in hand before you plan anything.
The permit exemption is not a zoning exemption. In Seattle's neighborhood residential zones the combined footprint of all structures is limited to a percentage of the lot, and setbacks keep accessory structures back from the front and side property lines. SDCI's shed guidance is the plain-language starting point, and the Land Use Code at SMC Title 23 is the operative text.
A moving or storage container placed in the public right of way in Seattle is a separate permit from the Department of Transportation, not from SDCI. Per SDOT Client Assistance Memo 2118, "portable containers for moving and storage and dumpsters placed in the public right of way (ROW) require a Street Use permit before they're delivered and placed," under SMC 15.04. The application asks for a right of way impact site plan, and the placement rule is specific: the container must be at least 10 feet from all driveways, 10 feet from hydrants and 30 feet from intersections. Street Use can be reached at (206) 684-5253 or [email protected].
If your container is going on your own property and your driveway approach is tight, that is a delivery question rather than a permit question, and our Seattle container delivery page covers approach and clearance.
Outside city limits, King County publishes a bulletin written specifically about this equipment. Cargo Shipping Containers: Building Permit Requirements, from the Department of Local Services Permitting Division, states the general rule plainly:
"When such containers are used as a building or structure, they are subject to the provisions of the building code as adopted and modified by King County. Accordingly, a building permit is required to locate and use such structures."
The bulletin then lists two exemptions: residential accessory storage structures less than 200 square feet, and a container used for storage of construction materials and equipment associated with a valid building or grading permit for the property on which it is located. Exempt structures must still be outside required setbacks, parking spaces and fire lanes, separated by at least 10 feet from all other buildings, compliant with all other building and site requirements, and "Non-heated, not used as a habitable space." The bulletin cites King County Code Sec. 16.02.240, work exempt from permit, and notes that structural calculations are required for altered or structurally connected containers.
Two things worth carrying from that document. First, a 20ft container at 160 square feet fits inside the King County exemption while the same box is above Seattle's 120 square foot line, which is exactly why the address matters more than the state. Second, the bulletin points out that building code approval of cargo containers may also be obtained through the Washington State Department of Labor and Industries, which is the factory route described below.
Tacoma has the most explicit container standards of our three cities, and reading them is a good education in how Washington cities think about this equipment. The rules were expanded by Ordinance No. 28903, part of the 2023 annual amendment to the comprehensive plan and land use regulatory code, and now sit in Tacoma Municipal Code Title 13.
TMC 13.06.020.G.9 provides that, except as noted, commercial shipping or storage containers are not a permitted type of accessory building in any residential zoning district. Two doors stay open. A container may be allowed as a temporary use under the limitations and standards in TMC 13.06.080.P. And a container may be allowed on a site with a valid conditional use permit, which in practice means uses like schools, parks and churches, subject to standards that include the following:
This is where Tacoma changed direction. Under TMC 13.06.100, shipping containers are allowed as an accessory structure in all Commercial Districts, subject to standards that include: not located between the building and street right of way, on corner lots applying to front and side; set back a minimum of five feet from all property lines; where not between the building and the right of way, set back further from the right of way than the wall of the building or five feet, whichever is greater; screened from any Residential District across an adjacent alley by a minimum six foot tall solid wood fence or landscaping; "Each site is limited to one shipping container"; and containers may not be placed within a shopping center as defined in TMC 13.01.060.S.
TMC 13.06.080.P covers temporary uses, and its temporary storage provision is written for exactly this equipment. Temporary storage units are allowed as part of an active construction project or active moving process, in conjunction with a conditional use to support that conditional use, or to support an agricultural use such as growing food, with food not sold from the site. In residential zoning districts the maximum duration of temporary storage is 180 days in any two-year period, with up to one 60 day extension at the discretion of Planning and Development Services. In commercial, mixed-use or industrial districts the unit is removed within 30 days after final inspection of the project, or where used in conjunction with a conditional use, a maximum of 180 days in a two-year period with one possible 60 day extension. Units must sit in the least conspicuous location available, provide a minimum five foot setback from all exterior property lines, and must not block emergency access, pedestrian or vehicular traffic, parking or access points.
Tacoma is not hostile to the equipment. It is specific about where the box sits and what it is doing there. Our Tacoma container delivery page covers approach and placement in the South Sound.
Across the Cascades the pattern changes, mostly because lots are larger and county jurisdiction covers more ground.
Spokane County publishes a permit exemption sheet, BP-25 Permit Exemptions, which exempts "One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided that the floor area is not greater than 200 square feet," referencing Spokane County Code 3.03.040 for the complete list. A 20ft container fits inside that threshold. A 40ft container does not.
The same sheet then says the sentence that matters most, and it is the same lesson in every Washington jurisdiction:
"Work that does not require a permit from Spokane County Building and Planning may require permit(s) from other departments."
It goes on to list the considerations most often overlooked on exempt work: structures are not allowed within land use setbacks or easements, there are additional requirements in a critical area such as a steep slope or wetland or its buffer or a shoreline, additions cannot push the property past lot coverage limits, structures cannot be placed on utilities, and structures cannot sit on county right of way without prior approval from Public Works.
Inside city limits, Spokane consolidates its development regulations into a Unified Development Code at Spokane Municipal Code Title 17, which carries the zoning districts, allowed uses and development standards. The right first call is the city's Development Services Center, and the city's residential codes page is the entry point. Ask them to read you the accessory structure standards for your zone and to confirm the city's own permit exemption threshold, which is not necessarily the county's 200 square feet.
Our Spokane container delivery page covers the run over Snoqualmie Pass and what that means for scheduling.
Spokane Valley is a useful illustration of how much a city line changes. Its code has long provided that "Cargo shipping containers and similar enclosures are not a permitted accessory structure in any residential zoning district," language the city moved in 2021 from its accessory dwelling unit standards at SVMC 19.40.030(D)(6) to its residential accessory structure standards at SVMC 19.65.130(A)(3). The city's own Planning Commission packet of July 22, 2021 also notes that residential accessory storage buildings no greater than 200 square feet do not require a building permit, that they must sit at least five feet from side and rear property lines and outside the front yard setback under SVMC 19.70.050, and that general outdoor storage in certain districts must be paved and screened with a six foot sight-obscuring fence or equivalent. Confirm the current text with the city before relying on it.
Washington regulates factory-built structures through the Department of Labor and Industries rather than through your local building department. RCW 43.22.450 defines factory built housing as a structure, including a factory built tiny house with or without a chassis, designed primarily for human occupancy other than a manufactured or mobile home, that is entirely or substantially prefabricated or assembled somewhere other than the building site. RCW 43.22.480 directs the department to adopt and enforce rules assuring that such structures are structurally sound and that their plumbing, heating, electrical and other components are reasonably safe.
In practice, under chapter 296-150F WAC, the manufacturer submits plans to the Factory Assembled Structures program, the state inspects at the manufacturing plant, and the department applies its insignia there after the final inspection. It then sends a Notification to Local Enforcement Agency that, in the program's own words, "Specifies what connections, standards, and incomplete items the local enforcement agency must check when the unit is installed." Your local building official still inspects the site work. The box arrives already reviewed.
King County's container bulletin points at this same route. If you are buying a finished container office or unit rather than a bare box, ask the fabricator whether it carries the Washington insignia. It changes what your local counter is looking at.
Most Washington jurisdictions that allow containers at all draw a line between a container tied to a specific, time-limited activity and a container that simply lives on the property.
Temporary means the container supports an active project: a build with a valid permit, a renovation, a move. Tacoma's rules are the clearest model in the state of how this gets written, with the trigger, the duration cap, the setback and the extension all spelled out. King County's exemption for a construction container tied to a valid building or grading permit is the same idea in one sentence.
Permanent means the container stays. That is when setbacks, lot coverage, screening, height, stacking limits and district use rules come into play, and in some districts the answer is that a container is not a permitted accessory building at all. If you intend permanence, settle it at the zoning counter first. It is a much cheaper conversation there than after delivery.
One call to your city or county planning and permitting counter, with the property address in hand, settles nearly all of this. Ask these, in this order:
Write down the name of the person who answered. If the answer later turns out to be wrong, that name is worth having.
We sell and deliver containers across Washington. We are not your permit office, we do not file applications for you, and we do not interpret your code. What we can do is give you accurate specifications so the conversation with your planner is a short one: exact external dimensions, footprint, height, weight, door swing, data plate information, and the clearance the delivery truck needs.
Washington delivered pricing, starting at $2,889 for a 20ft wind and water tight container delivered in Seattle, was captured from Container One on 6 August 2026. Every Washington delivery in this capture runs from the Seattle area depot, which is why Spokane sits higher. Here is the current picture across our three cities.
| City | 20ft WWT | 40ft WWT | 40ft High Cube WWT | Serving depot |
|---|---|---|---|---|
| Seattle | $2,889 | $2,889 | $2,783 | Seattle, 1.9 mi |
| Tacoma | $2,889 | $2,889 | $2,783 | Seattle, 33 mi |
| Spokane | $3,790 | $3,790 | $3,684 | Seattle, 279 mi |
Two honest notes on that table. Tacoma prices identically to Seattle on every grade in this capture even though it is 33 miles further out, so a Tacoma quote carries the same anchor without any shading. And in this particular capture the 40ft high cube prices below the 20ft, which is a supply artifact rather than a rule. If the extra length works on your site and in your setbacks, ask us to price both before you decide.
Every price above includes delivery. If you would rather spread the cost, ask about rent-to-own when you call.
If you are thinking beyond storage, our companion guides cover insulating a shipping container in Washington and container homes in Washington.
This guide is general information about how Washington jurisdictions handle containers, not legal advice, and codes and ordinances change. Confirm current requirements with your local planning and permitting department before you order.
Tell us the size you are considering and we will send exact dimensions, footprint, height and delivery clearance, so you can answer your planner's questions in one call. Washington delivered pricing: starting at $2,889 for a 20ft wind and water tight container delivered in Seattle. Price always includes delivery.