Multigenerational households are notably more common across York Region than the national average, driven by a combination of cultural norms in many of the communities here, housing costs that make two households harder to sustain than one, and a large population of parents who arrived in Canada with adult children already established locally.

This means the demand is real and so is the supply. Homes with in-law suites, second kitchens and separate-entrance basements trade regularly in both cities, and builders in newer Markham communities increasingly design for it. If you are looking for this type of home, it exists here in reasonable numbers, which is not true everywhere in the GTA.

A great many basement apartments across Markham and Richmond Hill were built without permits. They may look excellent. They may have been lived in for years without incident. None of that makes them legal, and the distinction becomes very real at three moments: when you try to insure it, when something goes wrong, and when you sell.

An unpermitted unit can complicate or void insurance coverage on a claim. It can be the subject of a municipal order requiring the space be brought into compliance or removed. And it surfaces during a sale, where a buyer's lawyer searches for permits, finds none and either walks or renegotiates.

Our renovation permits guide covers what happens when unpermitted work is discovered during a transaction.

Ask the seller directly whether the unit was permitted and request the documentation. Have your lawyer conduct the usual searches. Your municipality's building department can generally confirm what permits exist for a property. Where a suite is described as legal, the seller should be able to produce something in writing supporting that. If they cannot, treat the unit as unpermitted and price and structure your offer accordingly.

Ontario has moved over recent years to permit additional residential units more broadly in existing homes, with the intention of making it easier to create secondary suites. That provincial direction sets the framework, but each municipality implements it through its own zoning bylaws, and those bylaws set the specifics that actually govern your property.

Requirements that commonly come up include minimum ceiling height, egress windows of a specified size in bedrooms, a separate entrance, fire separation between units, interconnected smoke alarms, parking provision and the registration of the unit with the municipality.

These requirements change and vary between Markham and Richmond Hill. Do not rely on this or any general summary. Contact your municipality's building department about your specific property before committing to anything.

Ceiling height is the one that most often ends a basement conversion before it starts. Older homes frequently have basements below the required height, and lowering a basement floor is a major structural undertaking rather than a finishing job.

Egress windows are the second. A basement bedroom requires a window meeting size and access requirements, which on many homes means excavating a window well. Where the foundation, grade or lot line does not permit that, the room cannot legally be a bedroom regardless of how it is finished.

Where a parent contributes proceeds from selling their own home toward the purchase or the construction, everyone needs to be clear on what that money is. Is it a gift? A loan? Does it buy an ownership interest? What happens to it if the parent later moves into care, or if the home is sold, or if the parent passes away and there are siblings?

These questions feel awkward and families routinely avoid them. Avoiding them is precisely how a well-intentioned arrangement becomes a dispute between siblings years later, usually at the worst possible moment.

Put whatever you agree in writing, and have a lawyer document it properly. This protects the parent, the child they live with and the other siblings equally. It is not a sign of distrust. It is what responsible families do.

Where a portion of a home is used to earn rental income, or where ownership is structured across family members, there can be implications for the principal residence exemption and for how any eventual gain is treated. The treatment depends on the specific arrangement, whether rent is charged, and how title is held.

This is complex and the wrong assumption can be expensive. Speak with an accountant before you structure the arrangement, not at tax time afterward. Nothing in this guide is tax advice.

Families plan the construction in detail and the living arrangement not at all. Work through these before anyone moves in:

Meals. Together every night, occasionally or separately by default with invitations extended? Assumptions differ wildly here and disappointment builds quietly.

Visitors and privacy. Does anyone knock? Can a parent have friends over without it being an event? Can the adult children have an evening without a visit?

Childcare. If grandparents are expected to help with grandchildren, say so explicitly and agree how much. Assumed unlimited availability is a common source of resentment on both sides.

Household costs and chores. Who pays what, and who does what. Vague arrangements drift and then someone feels taken advantage of.

What happens if it does not work. Agree in advance that either side can say so without it being a catastrophe, and that there is a path to a different arrangement. Naming this at the start makes it far easier to raise later.

Whatever you agree beforehand will need adjusting once real life is running. Schedule a deliberate conversation at around six months to talk about what is working and what is not, before small irritations become entrenched. A planned check-in is much easier than raising a grievance out of nowhere.

In Markham and Richmond Hill, a legal secondary suite genuinely broadens the buyer pool. It appeals to other multigenerational families, to buyers who want rental income to help carry the mortgage and to investors. That demand is real and it supports value.

An unpermitted unit does the opposite. It must be disclosed, it worries buyers and their lawyers, it can complicate financing and it frequently becomes the point on which a deal is renegotiated or lost. The same physical space is an asset or a problem depending entirely on its paperwork.

If you are building a suite and expect to sell the home eventually, which almost everyone eventually does, do it with permits. The cost difference is far smaller than the value difference at sale.

Build the suite so it works for your parent and also functions as a normal secondary unit for whoever comes next. Highly specific modifications that only suit one person's needs, or a layout that sacrifices the main home's function in ways a future buyer would not accept, reduce the pool later. Sensible accessibility is broadly appealing. Idiosyncratic customization is not.