A dwelling can meet zoning limits and still need substantial technical review. Before comparing it with a checklist, establish the authority, classification, code edition, and whether the work is new construction, an addition, an alteration, or a conversion. Those facts determine which habitability, building-services, and energy provisions are relevant.

What the technical review may cover

Depending on the adopted code and project, review may include room and ceiling dimensions, natural light, ventilation, heating and cooling, moisture or radon, plumbing and drainage, electrical work, energy performance, commissioning, and inspection. A short government checklist can help identify questions, but it is not necessarily the complete code or a list of universal ADU requirements.

Ask the local building authority which plans, calculations, trade permits, tests, and inspection records are needed. Where the code requires a professional or licensed trade, confirm who may prepare, install, inspect, or certify the work. Do not treat a product manual, seller’s statement, or general code summary as approval of the complete dwelling.

Separate building compliance from utility capacity

Building code may address the design and installation of plumbing, electrical, heating, ventilation, and energy systems. A water or sewer provider, electric utility, or other service authority separately determines available capacity, connection terms, meters, and charges. Passing one review does not establish the outcome of the other. Keep provider capacity and connection approvals in the relevant utility inquiry.

Project state changes the energy path

California’s 2025 Energy Code FAQs distinguish a new detached ADU from attached additions and conversions. For that code, a new detached structure follows the new-building path; an attached unit or conversion of previously unconditioned space that increases conditioned area or volume is generally treated as an addition; converting conditioned space is treated as an alteration, with requirements triggered by covered component changes. The California Energy Commission’s ADU FAQs also explain that a factory-built housing label does not remove Title 24 energy-code questions. These are California rules, not a national classification.

Alberta offers another bounded example: provincial guidance states that houses with a secondary suite need independent heating and ventilation for the primary and secondary suites under the Alberta-adopted code. It does not answer whether a different unit form follows that route, whether a particular system is sufficient, or whether the municipality allows the use. Use the current Alberta secondary-suite guidance and confirm the applicable edition and municipal authority.

England and Wales have published future 2026 energy and ventilation guidance with different effective dates and transition facts. Do not apply either country’s dates to work in another UK nation, or assume that every secondary dwelling is classified the same way. See the focused England and Wales guides. England’s 2026 Approved Document L also introduces a future on-site renewable-electricity requirement for some new dwelling work; the England L3 guide explains its output method and project-transition limits.

Use a practical evidence checklist

For the proposed unit, collect the following before deciding what a rule requires:

  1. Local authority, unit classification, project state, and permit or application dates.
  2. The relevant code sections for light, room dimensions, ventilation, heating, plumbing, electrical work, energy, moisture, and radon where applicable.
  3. Plans or calculations required by the authority, along with responsible professional or trade credentials.
  4. Utility-provider findings kept separate from the code review.
  5. Inspection, commissioning, test, and completion records for the applicable work.

If the available source describes only a provincial or national example, use it to locate the issue, not to answer the local question. For an individual property, the adopted requirements and the responsible authority’s classification control.