Most Markham Basements Already Have the Height You Need

Second units and basement work in Markham

Most of Markham was built after 1975. Milliken Mills and Raymerville filled in through the late seventies and eighties. Cornell started in 1997. Wismer Commons, Greensborough, Angus Glen, Berczy Village and Cathedraltown are almost entirely a post-2000 story — Cathedraltown didn't take its first residents until 2006.

That matters more than anything else on this page. Those houses were built with full-height poured concrete foundations, weeping tile at the footing, damp-proofed exterior walls and, in most of the post-1995 stock, deep basements. When we tape joist-to-slab in a typical Markham subdivision house, we are usually already clear of the 1.95 m the Ontario Building Code asks for in an existing-house suite — often with room to spare for a dropped bulkhead under the main trunk line.

Compare that to the pre-war stock in old Toronto, where the first line on the estimate is underpinning or benching and $60,000 leaves before a single stud is stood up. In Markham, that line usually isn't there at all. We will still measure it before we quote — nobody should take a builder's word on head height — but the odds are strongly in your favour here.

## So the hard part is the outside, not the inside

The constraint in Markham is the exterior wall and the side yard.

Post-2000 Markham lots are deep and narrow. The builder put the gas meter, the hydro mast, the AC condenser, a hose bib and two window wells down the same 1.2 to 1.5 m strip you now want to cut a stairwell into — and on most of these lots that strip is also the only walking route from the front to the back yard. Half the work of a Markham separate entrance is deciding, on site, which side gets the stairs and what gets relocated. Sometimes the answer is the rear elevation instead, especially on a walkout or lookout lot where the grade already falls away and you can put in a full-height door with far less excavation.

We build the entrance itself in about three days: saw-cut the foundation, excavate, form and pour the stairwell and landing, set the door, install the drain and tie it in properly, install the guard. Then the interior suite follows on its own schedule.

## Registration with Markham Fire is not optional

This is the step homeowners get burned on. In Markham, a second suite is not legal simply because it passed the building inspection. The house has to be registered as a two-unit house with Markham Fire & Emergency Services, and Fire has to inspect it. For units built before July 1, 1993, the City uses a Two-Unit House Declaration Form to establish the construction date.

We have seen plenty of Markham basements finished by somebody else, framed decently, and worth nothing to an insurer or a mortgage lender because nobody ever closed the loop with Fire. When HMH builds a suite, the building permit, the inspections and the Fire registration are all part of our scope. You get a unit that is actually legal, not one that merely looks it.

## Where Markham gets complicated

Unionville and the Rouge. TRCA has designated part of Unionville a Special Policy Area — a pocket of the community that has historically sat in the Rouge River floodplain, between roughly Warden and Markham Road, 16th Avenue down to the 407. Ice jams around Main Street Unionville and high flows below Toogood Pond are documented history. If your property is in or near that area, a below-grade suite is a serious conversation about backwater valves, sump capacity and what TRCA will and won't permit. We would rather have that conversation before you spend money than after.

Four heritage districts. Thornhill, Markham Village, Unionville and Buttonville are all Heritage Conservation Districts with their own Council-approved plans. A new stairwell, a new door or a garden suite visible from the street is a heritage review, not just a building permit. It is doable — it is just a longer runway, and it should be priced that way from day one.

Cornell's laneways. Cornell was laid out by DPZ as a New Urbanist grid with garages off rear lanes. That is an unusual thing to find in the 905, and it makes Cornell one of the few places in York Region where a garage conversion or a rear-lane suite is a natural fit rather than a fight with the site.

The older pockets. Thornhill, Markham Village and the original Milliken houses predate the subdivision boom. Those are the Markham basements where head height genuinely can come up short and benching may be on the table. We measure first and tell you straight.

## What we build in Markham

Separate basement entrances and walkouts are our flagship — typically three days on site for the entrance itself. From there: legal basement apartments and second units, garden suites and garage conversions, home additions, and full renovations including kitchens, bathrooms, flooring, tile and countertops.

HMH Construction Inc. runs out of Mississauga with 25+ years in residential renovation, WSIB coverage, full insurance, and permits handled in-house. Markham is a straight run for our crews.

Call 905-749-4608 for a site visit. We will tape your basement, walk both side yards, and tell you honestly whether the suite works before you commit to anything.

Markham requirements

- Second suites must be registered with Markham Fire & Emergency Services as a two-unit house. The City states an accessory dwelling unit is not legal unless registered. A building permit or change-of-use permit comes first, then the Fire registration inspection. Markham Fire & Emergency Services: 905.415.7521. Building Standards: 905.475.4870. - Two-Unit House Declaration Form — required where an existing second suite was built before July 1, 1993, to establish the date of construction. - Provincial baseline: the Planning Act permits up to two additional residential units (three total) where single-detached, semi-detached and townhouse dwellings are permitted by zoning. Markham has been working through an Official Plan and Zoning By-law update, endorsed by Council in December 2023 under its Housing Accelerator Fund action plan, that would go to three ARUs (four units total) on most such lots. Confirm current status with Planning before relying on the fourth unit. - Zoning: Comprehensive Zoning By-law 2024-19, enacted January 2024, is the governing document. Setback, height, lot coverage, parking and site servicing capacity all still apply to any ARU. The City has stated ARUs will not be permitted in environmentally sensitive areas. - Ceiling height: 1.95 m over the majority of the floor area is the Ontario Building Code figure for a secondary suite in an existing house (Part 11 / Part 9 compensating provisions). This is provincial, not a Markham rule. - Unionville Special Policy Area (TRCA): a flood-vulnerable cluster in the Rouge River watershed, bounded roughly by Warden Avenue and Markham Road, and 16th Avenue to Highway 407, where two subwatersheds (Bruce and Middle-Beaver Creeks) meet the main Rouge. Ice jams historically occur near Main Street Unionville, south of Carlton Road to Victoria Avenue, and upstream of Kennedy Road. Milne Dam, in Milne Park, was rebuilt in 1969 after Hurricane Hazel damaged its predecessor. TRCA recommends backflow preventers in this area and permits are required for work in the regulated floodplain. - Four Heritage Conservation Districts: Thornhill, Markham Village, Unionville and Buttonville, each with its own Council-approved district plan and design guidelines governing exterior alterations. - Housing stock by era: Milliken Mills 1970s–80s; Raymerville 1980s–90s; Cornell from 1997 (DPZ-designed New Urbanist plan, garages on rear laneways); Angus Glen late 1990s onward; Wismer Commons, Greensborough, Berczy Village early-to-mid 2000s; Cathedraltown first occupancies 2006. Thornhill, Markham Village and original Milliken contain the city's genuinely older stock. - Garden suites: one self-contained garden suite per lot, and a lot may not have both a garden suite and a laneway suite; interior floor area must be less than the gross floor area of the principal dwelling. Confirm the current numbers against By-law 2024-19 for the specific property.