A rule quietly changed in Hamilton this summer

If you own a semi-detached house on an ordinary Hamilton street, the number of homes you are allowed to create on your lot changed this summer. Nobody sent a letter about it.

Here is the short version, and then the part that is still unsettled, because the second part matters as much as the first.

What the argument was actually about

The Planning Act permits additional dwelling units. The question that hung over Hamilton for years was a small one that turned out to be worth a great deal: when you have a semi-detached house, is that one building or two homes?

The City read it one way. The industry read it the other. Under the City’s reading, a whole semi got the additional units that the Province intended for each dwelling. Under the other reading, each half of the semi is its own dwelling and gets its own.

The difference between those two readings, on one ordinary lot, is the difference between four homes and six.

What changed

Through the spring and early summer of 2026, the City’s position moved. In late June, the City confirmed in writing that planning staff will apply the provincial legislation to allow two additional dwelling units within one half of a semi-detached dwelling, ahead of bringing forward the necessary changes to the City’s own zoning by-law.

In early July, the remaining piece landed too. The same permission was confirmed to apply inside Secondary Plan Areas, where older local zoning had not caught up.

So on a typical semi: a principal dwelling on each side, plus two additional dwelling units behind each. Six homes, in a house that still reads from the sidewalk as the house that has always been there.

Why this is the whole ballgame for infill

Gentle density does not fail because nobody wants it. It fails because of arithmetic.

An infill project carries fixed costs that do not care how many homes you build: the survey, the soil work, the servicing, the approvals, the consultants, the years. Spread across four homes, those costs are often enough to make a good project a bad investment. Spread across six, the same project pencils.

That is not a small technical win. It is the difference between a tired house staying tired and a tired house becoming six households on a street that already has the schools and the bus routes and the porches.

The part that is not finished

This is the honest caveat, and anyone telling you otherwise is selling something.

What exists today is a staff application position, not an amended by-law. The City has said how it will apply the provincial legislation in the interim. The formal zoning by-law amendment is a separate step, targeted for the autumn, and until it is enacted the by-law text and the practice do not match each other.

That gap is usually fine and occasionally is not. Site conditions, overlays, parking, servicing and heritage all still apply, and none of this removes the ordinary work of getting a permit.

So: do not read this as advice about your property. Read it as a reason to ask a real question about your property, to someone who will look at your actual lot.

Who did the work

Not us, mostly. This was four years of unglamorous committee work by the regional home builders association and its missing middle and infill subcommittee, plus planners and lawyers who kept making the same argument to the same people until the argument won.

We sit on that subcommittee, and the honest accounting is that we showed up for the last stretch of a long push that other people started.

It is worth saying plainly, because the story of how housing rules change is almost never a dramatic one. It is a small group of people reading a statute carefully and refusing to drop it.

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This is general information about a policy change, not legal or planning advice, and it is not a representation about what any particular property is permitted to do. Zoning, site conditions and municipal approvals vary lot by lot. If you are weighing a specific site, talk to a planner, or send it to us and we will tell you what we actually think.