Unionville Heritage Conservation District Rules Explained

The short answer

• Unionville is one of four heritage conservation districts in Markham, along with Buttonville, Markham Village and Thornhill, each protected under Part V of the Ontario Heritage Act.
• Being inside the district boundary triggers permit requirements on every property, whether or not that specific house is individually designated.
• A Minor Heritage Permit covers things like window replacement, new siding, driveways and visible mechanical equipment, while a Major Heritage Permit covers additions, new builds and demolition.
• Routine repairs such as eavestroughs, existing cladding repair and backyard structures hidden from the street are generally exempt.
• You can check a property’s status using the City’s Heritage Conservation District maps or the Markham Register of Property of Cultural Heritage Value or Interest.
• Buyers should build time into their closing timeline for permit questions, since Heritage Section review is a separate step from a standard building permit.

Why Unionville Has Its Own Set of Rules

Unionville was settled in 1794 and still has one of the most intact 19th-century main streets in York Region. The City of Markham designated it a heritage conservation district under Part V of the Ontario Heritage Act, which is a different and stronger tool than designating a single building. A district designation covers a whole area, streetscape, lot pattern and all, not just the facades people usually notice.

The City describes a heritage conservation district as a defined boundary where every property is protected from inappropriate change, using policies and design guidelines specific to that area. That is the piece buyers in Unionville or Markham Village often miss: it is not only the obviously old buildings that are covered. If your lot sits inside the mapped boundary, the rules apply to you, even if the house itself was built decades after the district’s founding era.

What Falls Under Unionville Heritage Conservation District Rules

The City of Markham requires a Heritage Permit before any external alteration, new construction or demolition on a property that is individually designated or sits inside a heritage conservation district. For Unionville specifically, that means checking the Unionville Heritage Conservation District Map before you assume a project is a simple one.

Projects that typically need a Minor Heritage Permit include:

• New or different wall cladding or roof treatment
• Removal and replacement of windows or doors
• Changes to architectural decoration such as verandas, trim, soffits, fascia or awnings
• Front yard patios, lamp installations, walkways and driveway changes
• Mechanical equipment visible from the street
• Exterior repairs that change the building’s appearance

Larger projects, such as additions, new construction or anything involving demolition, typically require a Major Heritage Permit. The exact line between the two is set out in By-law 2023-20 and the City’s own guidance recommends talking to Heritage Section staff before you assume which category your project falls into.

What Does Not Need a Permit

Not everything in the district requires sign-off. General repairs, such as fixing weather-stripping, eavestroughs, chimneys, fences or existing cladding, are usually exempt. So is repairing a broken window pane to its original specification and small backyard structures like sheds, gazebos or patios that are not visible from the street and do not need a building permit on their own. Planting or removing vegetation is also exempt, though removing a tree is handled under a separate tree permit process.

The Buyer’s Blind Spot: Falling for the Street, Not the Fine Print

This is where things go sideways for buyers. Someone walks Main Street in Unionville, falls for the mature trees, the 19th-century storefronts and the character of the house and makes an offer without ever asking whether the property sits inside the heritage conservation district boundary. Then six months later they want to replace tired windows or build a small addition and discover the project now involves a Heritage Permit application, design review against the district’s heritage plan and a timeline measured in weeks or months rather than days. None of that means the house was a bad purchase. It means the process for changing it is different from a non-designated property and that difference should be priced into the decision, not discovered after the fact. A buyer who knows going in that their dream renovation needs heritage approval can plan for it. A buyer who finds out after closing often feels blindsided, even though the information was public the whole time.

Heritage Designation and New Development Nearby

It is also worth understanding that heritage conservation district rules do not freeze an area in time and they do not block all new construction. The City is explicit that these districts are “living parts of our community, not museum sites,” and that the goal is to guide change so it complements the area’s character rather than erase it. That means new infill, additions and even larger developments can and do happen inside the district, provided they go through the Heritage Permit process and meet the design guidelines in the relevant Heritage District Plan.

Buyers should also pay attention to proposed development near a property they are considering, even outside the immediate heritage boundary. Larger projects affecting multiple addresses along a historic street can change traffic, parking and the feel of a block over time, even when individual heritage buildings are preserved or relocated as part of the plan. Checking current development applications with the City or asking your agent to do so, is a reasonable step before buying on or near Main Street.

Minor vs Major Heritage Permit: A Side-by-Side Look

Project type	Permit usually required	Typical examples
Routine repair, no change in appearance	None	Eavestrough repair, chimney repair, fence repair, existing cladding repair
Visible exterior change	Minor Heritage Permit	New windows or doors, new cladding or roofing, driveway changes, front yard patios, visible mechanical equipment
Hidden backyard structure	Usually none, if not visible from the street and no building permit is needed	Garden shed, gazebo, small backyard patio
Addition or new construction	Major Heritage Permit	Second-storey addition, new infill house, rear extension
Demolition of any part of the structure	Major Heritage Permit	Removing a historic barn, outbuilding or main structure

How to Check a Property’s Heritage Status Before You Buy

Before you get attached to a house in Unionville, there are a few concrete steps worth taking:

• Look up the Unionville Heritage Conservation District Map on the City of Markham’s website to see whether the address falls inside the boundary.
• Search the Markham Register of Property of Cultural Heritage Value or Interest to see if the property is individually listed or designated on top of being in the district.
• Ask for a copy of the Unionville Heritage District Plan if you have specific renovation plans, since it sets out the design guidelines staff will apply.
• Have your real estate lawyer confirm heritage status as part of the standard title and municipal search during your purchase.
• Call Markham’s Heritage Section directly if you have a specific project in mind. Staff consultation before you apply is recommended by the City itself.

What to Do Next

If you are actively looking at homes in Unionville, Markham Village, Buttonville or Thornhill, start by checking the district map against any address you are seriously considering. If you already own in one of these districts and are planning a renovation, call Heritage Section staff before you order materials or sign a contractor, since a project that seems minor to you may fall under the Major Heritage Permit category. And if you are weighing whether a heritage property is right for your plans at all, it is worth a conversation before you write an offer, not after.

I work with buyers and sellers across Unionville and the rest of Markham regularly and questions about heritage status come up more often than people expect. If you are looking at a property in one of these districts or thinking about listing one, reach out to me, Kirby Chan and I will help you get clear answers before you are locked into a decision.