There is no universal retrofit checklist for an unpermitted accessory dwelling. The responsible authorities must assess the actual structure, its approval history, its current use, and the rules that apply to that location and project date. A general list can help you prepare questions, but it cannot predict which work a particular unit needs or whether an alternative will be accepted.
Establish the scope before estimating work
Gather available permits, drawings, inspection records, alteration dates, and information about the unit’s present layout and services. Have the authority identify the permit pathway, applicable code edition or historical treatment, and which agencies need to review the property. Missing records should lead to a records request or site-specific assessment, not a guessed construction standard.
Areas an assessment may cover
Depending on the jurisdiction and project, an inspection or plan review may consider:
- fire separation between the unit and the main dwelling, exits, escape openings, smoke and carbon-monoxide alarms, and fire access;
- room dimensions, ventilation, heating, structural condition, moisture, and habitability;
- electrical, plumbing, gas, water, sewer, septic, or other service connections;
- access, zoning and site constraints, easements, flood or conservation areas, and other approvals; and
- whether the actual work matches approved plans and whether later changes need separate permits.
Ontario’s second-unit guidance lists building and life-safety subjects such as fire separation, alarms, egress, room dimensions, windows, plumbing, heating and ventilation, and electrical work. It is a screening example, not a determination for every Canadian unit. Ontario conservation permissions may also apply to certain regulated areas and activities; they are separate from municipal building or planning review.
British Columbia says its Fire Code applies to existing buildings and that a site-specific evaluation is essential to determine whether required safety features are present. An authority may accept an alternative when satisfied that an equivalent level of fire and life safety is achieved. That is a decision the authority makes on evidence; age does not automatically exempt a suite.
Calgary’s advisory for certain suites said to predate March 12, 2018 describes an authority assessment and gives examples such as egress, separations, and alarms. The advisory expressly says it has no legal status and is not an official interpretation of current bylaws or codes. Confirm the current code path and any accepted alternative with Calgary before relying on it.
Plan for concealed work and multiple approvals
Completed walls or ceilings may hide wiring, plumbing, framing, or fire separation. A legalization process may require a qualified professional, additional plans, a trade permit, opening finished surfaces, corrective work, and staged or final inspections. A city’s building permit does not necessarily resolve a separate electrical, fire, utility, conservation, or septic approval.
Ask each authority to identify the documents and inspection results that will close its part of the review. Keep written decisions with the property records, and compare them with the final work. For a broader process, see retrospective approval and regularization. For New York City’s local violation process, see the illegal-conversion correction guide.
Do not use this list as a safety determination
This article cannot establish whether a unit is structurally sound, fire-safe, code-compliant, or occupiable. Do not rely on its age, a photograph, an old permit, or an alternative-compliance discussion as a substitute for the required inspection. Use the responsible authority and qualified professionals for the property-specific assessment.