The one structural fact about US building regulation
No US state universally allows or disallows residential onsite storage containers — all regulation is done locally by the city or county. A state-level answer is never the final answer. What a state-level guide can do is tell you what kind of regulatory environment you're in, what questions to ask, and which specific issues are likely to come up where you are.
In this guide
The Model Codes Underneath Everything
Almost every US jurisdiction bases its rules on the International Code Council model codes. Understanding what those say about containers tells you what to expect nearly anywhere.
| Code section | What it does |
|---|---|
| 2021 IBC § 3115 / 2024 IBC § 3114 | The first model-code section written specifically for intermodal shipping containers repurposed as buildings. Renumbered in the 2024 edition. |
| 2021 IRC § R301.1.4 | New in the 2021 edition. Requires that containers repurposed as buildings be designed per the structural provisions of IBC § 3115. Before 2021, every building department improvised. |
| 2021 IRC § R202 | Adds a definition: an intermodal shipping container is a six-sided steel unit originally constructed as a general cargo container for the transport of goods and materials. |
⚠️ Why the code edition your jurisdiction uses matters
If your jurisdiction is on the 2021 IRC or later, container homes have a defined path. If it's on the 2018 IRC or earlier, your project will be evaluated under the alternative materials and methods provision — which is legal and workable, but gives the building official far more discretion and puts more weight on your documentation. Check which edition your jurisdiction has adopted before designing anything.
IBC § 3115 structural requirements in brief
| Provision | Requirement |
|---|---|
| Construction documents | Must verify container dimensions and establish the physical properties of the steel and wood floor components |
| Data plate | Container must bear a data plate with items required by ISO 6346, verified by an approved agency, with a verification report provided to the owner |
| Structural design | Containers conforming to ISO 1496-1 must be designed per IBC Chapter 16 |
| Foundations | Designed and constructed per IBC Chapters 16 through 23 |
| Anchorage | Anchored as necessary to provide a continuous load path for all applicable design and environmental loads |
| Welds | New welds and connections must equal or exceed the original connections in strength |
| Simplified design path | Available only for a single stand-alone container, uncut at rails/castings/columns, level with floor at bottom, in Seismic Design Category A–D |
⚠️ Almost no container home qualifies for the simplified path
A single container, not joined to anything, with no cuts into corner castings, columns, or bottom rails. A typical container home joins two or more units and cuts openings for windows and doors. Either condition disqualifies you. Budget for detailed structural design from the outset — planning around the simplified path and discovering at plan review that you don't qualify is the expensive version.
The Steel Documentation Problem
This is the issue with no equivalent in conventional construction, and it's the same in every state.
The core problem
Ordinarily, approval of structural steel includes mill reports and welding specifications. However, approximately 97% of containers are built in China and this information is often unavailable. — Intertek
A plan reviewer evaluating a steel structure expects mill certifications establishing grade and properties, plus welding procedure specifications. For a used container bought from a depot, neither exists in obtainable form. The container was built as freight equipment; its paper trail was never designed to satisfy a building official.
AC462 — the mechanism built to close the gap
| Item | Detail |
|---|---|
| What it is | ICC-ES Acceptance Criteria 462, "Structural Building Materials from Intermodal Shipping Containers," introduced in early 2016, dated October 2018 |
| Purpose | Establishes criteria and a protocol for evaluating reused shipping containers as a building product — specifically addressing the missing mill certification problem |
| How it's used | A manufacturer obtains an ICC-ES evaluation report (ESR), submitted with the permit application as evidence the container material complies |
| Report holders | SG Blocks (ESR-3764, the first issued), Craftsmen Industries (ESR-4478), Container King (ESR-5226) |
| Scope limit | An ESR verifies the steel for use with AISC 360 and AISI S100. It does not design your house. Complete construction documents and sealed calculations are still required. |
Sources: ICC-ES ESR-3764, ESR-4478, ESR-5226; ICC Evaluation Service; Intertek. ESRs are free to read at icc-es.org.
Residential Code Requirements That Catch Projects
Ceiling height — the constraint that picks your container
| Standard container | High Cube container | |
|---|---|---|
| Interior height (bare) | ~7ft 10in | ~8ft 10in |
| Typical finished height | ~7ft 0in–7ft 2in | ~8ft 0in–8ft 2in |
| IRC § R305.1 minimum | 7ft (2,134mm) | 7ft (2,134mm) |
| Margin over minimum | Essentially none after floor and ceiling assemblies | ~1ft — comfortable margin |
Note on a widely repeated error
At least one container-industry source states IRC R305.1 requires 7ft 6in. It does not. The requirement is 7ft (2,134mm), consistent across ICC materials, municipal handouts, and the code text. The practical advice is unchanged — buy High Cube — but verify code requirements against the code, not industry sources.
| Requirement | Code section | The container-specific issue |
|---|---|---|
| Ceiling height | IRC § R305.1 | Standard container leaves essentially no margin after floor and ceiling assemblies. Buy High Cube. |
| Emergency escape and rescue | IRC § R310 | Every sleeping room needs one with a net clear opening of not less than 5.7 sq ft. Cutting it into a corrugated wall is a structural modification. |
| Egress door | IRC § R311.2 | Side-hinged door with 32in minimum clear width. The container's cargo doors do not satisfy this — a new compliant door must be cut in. |
| Energy code | IRC Ch. 11 / IECC | Insulating a steel box without condensation problems is a real building-science challenge. The assembly must be documented and calculated. |
| Flood hazard | IRC § R322 | Elevated foundations required in Special Flood Hazard Areas. Containers float — this is a serious engineering condition, not a formality. |
| Foundation | IRC Ch. 4 / IBC Ch. 18 | No specified type, but must be engineered for concentrated corner loads with footings below frost line. A container's load transfers through four corner castings, not a distributed bearing area. |
Texas
Texas — Most permissive, most variable
No statewide residential code mandate · Local adoption and enforcement · Sharp city/county divide
Texas has no statewide building code mandate for private residential construction and no statewide restriction on shipping containers. Each city and county adopts, amends, and enforces independently. What is perfectly fine on an acre in an unincorporated county can trigger a code enforcement notice inside a city a few miles away.
| Setting | What to expect |
|---|---|
| Unincorporated county | Often minimal or no permit requirement for storage containers. Some counties enforce only septic and floodplain provisions. One builder reports their unincorporated county requires permits only for driveway entrances and septic tanks. |
| Inside city limits | Full zoning and building permitting — accessory structure standards, setbacks, lot coverage, height limits, and often screening requirements. |
| Either | Deed restrictions and HOA covenants apply independently of government rules and are common in Texas subdivisions. |
Representative municipal rules
| Jurisdiction | Reported rule |
|---|---|
| Whitesboro | Containers allowed in residential districts only on properties of at least one acre — one container per acre |
| Jacksonville | Cargo containers permitted as accessory storage only in specific zoning districts (J, K, L, M and O) |
| Austin | Permanent accessory containers in residential zones require a permit and must meet setbacks, lot coverage, and screening standards |
| Fort Worth | Storage buildings generally require a building permit — regulations cover location, maximum height, square footage, and screening from public view |
| El Paso | Permanent containers on residential lots generally require a permit and must meet accessory structure standards |
Sources: Conexwest Texas zoning summary; Storage Containers Houston city-by-city guide. Verify directly — ordinances change.
⚠️ The Texas trap
"No permit required" in an unincorporated county does not mean no consequences — it means no inspection, which affects financing, insurance, and resale. Lenders and insurers frequently want evidence of code-compliant construction regardless of whether the county required it. Build to code even where nobody checks.
California
California — Most structured, with a second path
IBC § 3115 in CBC · HCD Factory-Built Housing route · Strong statewide enforcement
California adopted IBC § 3115 into the California Building Code (Title 24) and added a state-specific amendment: shipping containers constructed or converted off-site that qualify as Factory-Built Housing must be approved by the Department of Housing and Community Development. That creates two routes to a permitted container dwelling — and they are administratively very different.
| Route | How it works | Trade-off |
|---|---|---|
| Site-built under CBC § 3115 | Containers delivered and modified on site, permitted by the local building department like any other construction | Full local plan review. Maximum design flexibility. |
| HCD Factory-Built Housing | Containers constructed or converted off-site by an approved manufacturer, with designs reviewed by an HCD-certified Design Approval Agency | State law provides local building departments may not require plan review or charge plan check fees where HCD has already approved. Local department still permits and inspects site installation and utility connections. |
What a California permit package contains
| Document | Notes |
|---|---|
| Architectural plans | Floor plans, elevations, and cross-sections showing all modifications to each container — licensed architect |
| Structural engineering calculations | Load analysis, reinforcement details for each opening, and foundation design — stamped by licensed structural engineer |
| Container documentation | Data plate information for each container plus the verification report required by CBC § 3115.3.3 |
| Soils report | Geotechnical investigation to inform foundation design |
| Title 24 Part 6 energy compliance | Calculations or performance modeling — mandatory envelope, ventilation, HVAC, lighting, and hot water requirements |
San Diego as a worked example
The City of San Diego publishes Information Bulletin 149 specifically on cargo containers repurposed as buildings. It states that cargo containers must comply with CBC Chapter 31 Section 3115; that a building permit is required to install cargo containers except in narrow cases such as permitted special-event stage sets; and that separate electrical, mechanical, and plumbing permits are required whenever a container is supplied with electricity, gas, water, or sewer.
Source: City of San Diego Development Services Information Bulletin 149 (government).
The ADU angle worth knowing
Where a jurisdiction resists a container primary residence, a container ADU on the same lot may face fewer obstacles — California's state ADU statutes constrain how much local jurisdictions can restrict accessory dwelling units. Several manufacturers now produce HCD-approved container ADUs specifically for the California market. This is worth raising with your jurisdiction early.
Florida
Florida — Highest engineering bar in the country
Florida Building Code · HVHZ in Miami-Dade and Broward · ASCE 7-22 wind loads · FPA required
Florida operates under the Florida Building Code (8th Edition, effective December 31, 2023), which adopts ASCE 7-22 for wind load calculations. Miami-Dade and Broward counties are the nation's only High-Velocity Hurricane Zone jurisdictions — ultimate design wind speeds there typically run around 170–180 mph for Risk Category II. All structural calculations must be sealed by a Florida-licensed PE or architect.
| Requirement | Detail |
|---|---|
| Statewide product approval | Under Florida Statute § 553.842, products critical to structural integrity and wind resistance — windows, doors, roofing — must carry a valid Florida Product Approval number |
| HVHZ Notice of Acceptance | Inside Miami-Dade and Broward, exterior envelope products need a Miami-Dade NOA or Broward Product Control approval, tested to TAS protocols |
| Large missile impact (TAS 201) | Glazing must withstand a 9-pound 2×4 fired at 50 feet per second |
| Cyclic pressure (TAS 203) | Thousands of alternating pressure cycles plus wind-driven rain |
| Continuous load path | An engineered continuous load path from roof to foundation — required for new construction and substantial improvements in the HVHZ |
| Approval currency | Approvals renew — an expired FPA or NOA is not approval. Verify at install, not just at specification. |
The upside of steel in hurricane country
A container is a steel box, and steel boxes are structurally well suited to hurricane loads. The engineering is demanding but the material is on your side. The challenge is documentation and product compliance — not the structural performance of the container itself.
Outside the HVHZ, most of Florida is described as reasonable about containers. The two factors that complicate Florida everywhere in the state are hurricane wind load requirements and flood zone regulations — both of which affect where and how a container can be placed regardless of county.
Sources: Florida Building Code; Florida Statute § 553.842; windload.solutions HVHZ references.
Arizona
Arizona — Local adoption, sharp urban/rural divide
No statewide container restriction · Phoenix and Tucson require full plan review · Climate drives review focus
Arizona has no statewide container restriction. Cities and counties adopt the IBC and IRC and enforce independently. Rural and unincorporated counties are generally accommodating. Phoenix (Maricopa County) and Tucson (Pima County) require permits and conduct thorough plan review.
| Region | Counties | Plan reviewer focus |
|---|---|---|
| Low desert | Maricopa (Phoenix), Pima (Tucson), Yuma, Mohave | Heat rejection — energy calculations, SHGC values, envelope performance. Maricopa is described as streamlined but strict on energy calculations and engineering details. |
| High country | Coconino (Flagstaff), Yavapai (Prescott), White Mountains | Snow load calculations, frost-line foundation depth, heat retention. |
| Pima County specifically | Tucson and surroundings | Desert conservation, floodplain management for monsoon arroyos, and hillside development ordinances layered on standard IRC requirements. |
⚠️ One notable Maricopa County restriction
Unincorporated Maricopa County reportedly treats storage containers as accessory buildings with placement limits and does not allow a shipping container as an accessory dwelling unit. A full container dwelling must clear zoning and full IRC permitting. Verify directly with the county — this is from a builder's FAQ, not the ordinance text.
Sources: Conexwest Arizona summary; Jematell Homes Arizona FAQ; permitcontainerhomes.com Arizona guide.
10 More States
Read this table as orientation, not authority
These entries come from industry surveys and state code adoption records — necessarily generalized. Use them to understand what kind of regulatory environment you're entering and what to ask. Call your building department for anything that affects a purchase decision.
| State | Regulatory character | Container-specific notes |
|---|---|---|
| Pennsylvania | Statewide Uniform Construction Code with local amendment | The most container-specific state provision found: 34 Pa. Code § 403.21 requires, prior to permitting, third-party certification that the unit is free from contaminants by a qualified inspector approved by the AHJ, AND certification by a PA Registered Design Professional for any penetrations beyond those permitted in IBC § 3115. Worth studying even if you build elsewhere — the contamination requirement reflects a real issue. |
| Michigan | Statewide residential code | 2021 Michigan Residential Code adopted R301.1.4, described as providing criteria for minimum safety requirements when repurposing containers, new and used, for occupiable use. |
| New York | Statewide code with local amendment; NYC is separate | Container use as buildings recognized in the IBC with criteria established. Urban jurisdictions described as strict. |
| Tennessee | Local adoption; urban jurisdictions require permits | Permitted in most rural areas; HOA restrictions common in developed subdivisions. |
| Georgia | Statewide minimum standard codes with local enforcement | Legal with some counties requiring permits; storage use reported as minimally restricted. |
| North Carolina | Statewide building code | Container homes permitted where they meet the same structural, safety, and livability standards as other single-family residences — foundations, engineered plans, full inspections. |
| Colorado | Local adoption; no statewide residential code | Wide county-level variation. Mountain jurisdictions add snow load and wildfire considerations. |
| Oregon | Statewide specialty codes | Statewide framework means less local variation than neighboring states; seismic provisions apply west of the Cascades. |
| Washington | Statewide code with local amendment | Some municipalities prohibit cargo containers as accessory storage in residential zones outright. Lakewood, WA is one documented example (Municipal Code 18A.60.195). |
| Missouri | Local adoption; no statewide residential code | Rural counties reported to allow containers with minimal restriction; St. Louis and Kansas City metros enforce full permitting. |
The Permitting Process — In Order
- Get a written zoning determination for your specific parcelAsk whether a single-family dwelling built from repurposed intermodal containers is a permitted use — and get the answer in writing. Ask about setbacks, height, and lot coverage while you're there.
- Check private restrictionsDeed restrictions and HOA covenants operate independently of zoning and can prohibit what the jurisdiction allows. This is especially common in Texas and Arizona subdivisions.
- Confirm the adopted code editionsWhich IBC and IRC editions, what local amendments, and is the container section numbered 3115 or 3114 — or absent entirely? Ask this directly.
- Ask the container question directly"Do you require an ICC-ES evaluation report or equivalent? Have you permitted a container dwelling before?" A jurisdiction that has permitted one knows the path. One that hasn't will have questions you need to help answer.
- In California — decide your routeSite-built under CBC § 3115 or HCD Factory-Built Housing. The routes have different administrative paths and different local plan check obligations.
- In Florida — establish your wind and flood conditions firstDesign wind speed, HVHZ or wind-borne debris region status, and flood zone — before designing anything. These shape every subsequent decision.
- Engage a licensed engineer or architect before the design is finishedThe structural approach shapes the design. Late engineering means redesign. The structural engineer's input on opening size and location, container configuration, and foundation type needs to happen while there's still time to change it.
- Assemble the full submittal package and submit it completeIncomplete applications are the most commonly cited cause of avoidable delay across every source. See the submittal package below.
- Respond to correction notices promptlyPlan review comments are normal — they do not mean the project is rejected. Respond quickly and completely.
- Schedule inspections at each checkpointTypically: foundation, framing, rough-in MEP, insulation, final. The certificate of occupancy is the last step — the structure is not legally habitable until it's issued.
The Universal Submittal Package
| Document | Notes |
|---|---|
| Permit application | Through the jurisdiction's portal where one exists |
| Site plan | Dimensioned, showing placement, setbacks from all property lines, and site access |
| Architectural drawings | Floor plans with room labels, elevations, sections — prepared by a licensed architect where required |
| Structural calculations, sealed | For openings, wall removals, multi-container connections, and foundation — stamped by a licensed structural engineer |
| Foundation design | Engineered for concentrated corner loads, with footings below frost line |
| Connection details | Container-to-container and container-to-foundation connections |
| Container documentation | Data plate verification report; ICC-ES evaluation report where required by the jurisdiction |
| Energy compliance | REScheck, Title 24 forms, or state equivalent |
| Soils report | Where required by the jurisdiction or engineer |
| Product approvals | Florida: FPA numbers or NOAs for all envelope products |
| Flood documentation | Where the site is in a Special Flood Hazard Area |
Free: Permits & Approvals Checklist
Pre-design, zoning, design, submittal, and inspection checklists — every step from first zoning call to certificate of occupancy.
Common Mistakes
| Mistake | Consequence |
|---|---|
| Relying on a state-level answer | Regulation is local. A state guide tells you the climate, not the rule. |
| Buying land or containers before confirming zoning | Zoning is categorical. No engineer can fix a prohibited use. |
| Assuming HOA approval follows zoning approval | They are independent. HOA covenants are especially common in Texas and Arizona subdivisions. |
| Planning around the simplified structural path | Joining containers or cutting corner castings, columns, or rails disqualifies you. Budget for full structural design from the start. |
| Buying standard-height containers | ~7ft 10in bare interior leaves essentially no margin after floor and ceiling assemblies over the 7ft IRC minimum. |
| Treating an ESR as an engineering package | It verifies the steel as a material. Project-specific sealed calculations are still required. |
| In Texas: treating "no permit required" as "no standards apply" | Lenders and insurers frequently want evidence of code-compliant construction regardless of whether the county required a permit. |
| In California: missing the HCD route | Factory-built approval can remove local plan check entirely for the manufactured portion — a significant time and cost saving. |
| In Florida: specifying products without current approvals | An expired FPA or NOA is not approval, and causes permit denial or expensive tear-out. |
| Engaging an engineer after drawings are finished | The structural approach shapes the design. Late engineering means redesign. |
| Submitting an incomplete package | The most commonly cited cause of avoidable delay across every source consulted. |
Questions for Your Building Department
| # | Question |
|---|---|
| 1 | Which editions of the IRC and IBC do you enforce, and what local amendments apply? |
| 2 | How do you evaluate repurposed shipping container structures? Have you permitted one before? |
| 3 | Do you require an ICC-ES evaluation report or equivalent for the container material? |
| 4 | Must construction documents be sealed by a licensed engineer or architect for this project? |
| 5 | Is this site in a Special Flood Hazard Area, a wind-borne debris region, or a wildfire hazard zone? |
| 6 | What is your plan review turnaround, and do you offer a pre-application meeting? |
Where to find authoritative information
ICC Digital Codes (codes.iccsafe.org) — IBC § 3115/3114 and IRC R301.1.4 free to read. ICC-ES (icc-es.org) — AC462 and evaluation reports, free to read. California HCD — Factory-Built Housing program and approved manufacturers. Florida DBPR — statewide product approval database. Your local building department — the only authoritative answer.