What does the Building Code ask of the unit?
The City lists these for an ADU inside a house (City of Hamilton, Additional Dwelling Units, read November 5, 2026):
| Item | What the City says |
|---|---|
| Age of the house | Different Building Code rules apply depending on the age of the house. |
| Fire separations | Required between the unit and the rest of the house |
| Heating | One furnace may serve both, with a smoke detector in the ducts that shuts it off; newer homes may need two systems |
| Smoke alarms | CAN/ULC S531, wired, interconnected, with a flashing light |
| Carbon monoxide | Detectors where there is a fuel burning furnace or an attached garage |
| Exits, windows, ceiling heights, room sizes | Minimums that depend on where the unit is in the house |
| Plumbing | Hot and cold water, sink, tub or shower, toilet, kitchen sink and access to laundry |
| Water service | May need a bigger pipe and meter; a lead pipe may need replacing |
| Septic | Allowed if the system can take the extra sewage, otherwise a permit to upgrade it |
What if the Fire Department has already been?
Then the Fire Order goes with the permit application. The City: Apply for building permit in the normal manner with the Building Division. With your application form include the Fire Order Number for reference in the description of work. Submit a copy of the Fire Order and architectural drawings reviewed, approved and stamped by the Fire Department.
(City of Hamilton, Additional Dwelling Units, read November 5, 2026) An owner can also ask the Fire Department for a paid inspection: $733.10 with HST for a house with two dwellings in 2026, including a compliance letter (Hamilton Fire Department, Residential and Commercial Inspections, read November 5, 2026).
Does it need parking, or development charges?
Usually neither. The City says that under its amended by-laws additional parking spaces for up to 3 units are now exempt
, with more review for newer buildings (City of Hamilton, Additional Dwelling Units, read November 5, 2026). And the 2026 to 2027 development charges include a 100% exemption for up to two ADUs in a house (development charges). The zoning still decides how many units the lot may have: can my house have an ADU?
Why bother?
Because the alternative is an order: building without a permit lists what the City can do, including an order registered on title. A permitted unit also gets its own municipal address.
How does JDT approach it?
JDT draws the house as it is and what has to change, then prices the whole of it in one written proposal. The ADUs page covers the bigger picture, and finishing a basement covers basement work that is not a unit. Under JDT Construction Inc.'s agreement the homeowner applies for the permit and pays the City's fees; who applies for a building permit explains how that works.