Buying one of the older homes in Markham: what to check before you firm up

The short answer

If you are moving up to one of the older homes in Markham, the house will come with wiring, pipes and insulation installed under the standards of its day. Before you firm up an offer on an older detached house, check the wiring, any insulation that could contain asbestos, the private water service pipe, how the basement is protected from flooding and whether past renovations had permits.

Two City of Markham rules also shape what you can do after you move in. Properties in the four heritage conservation districts need a heritage permit for exterior alterations. Private trees with a trunk diameter of 20 centimetres or more need a permit before they are cut down.

A home inspection is where most of this starts. Our post on what a home inspection covers and misses explains its limits. This post covers the checks that go beyond it on an older house.

Wiring: knob and tube and aluminum

The Electrical Safety Authority (ESA) names two older wiring types that matter to buyers.

Wiring	When ESA says it was used	What ESA says about insurance
Knob and tube	Early 1900s to 1940s	Many insurers will not provide or renew coverage. Some require replacement first
Aluminum	Homes built between the mid-1960s and late 1970s	Some insurers will not provide or renew coverage without an ESA inspection

ESA says knob and tube wiring “is safe, provided it is properly maintained by a Licensed Electrical Contractor.” ESA says it is no longer used. The latest Ontario Electrical Safety Code removed its installation rules, but ESA notes the code “is not retroactive.” Older systems also lack modern protections such as ground fault circuit interrupters in wet areas.

ESA says aluminum wiring “is safe if proper connections and terminations are made without damaging the wire.” For either type, it recommends hiring a Licensed Electrical Contractor (LEC) to assess the home’s electrical system. ESA points out that this assessment looks only at the electrical system, which is different from a home inspection. For aluminum wiring, the LEC should make any repairs, have the work inspected by ESA and give you a copy of the Certificate of Acceptance, which your insurer may ask for.

The practical step: call your insurer while your offer is still conditional. If they need an ESA inspection or a rewire before they will cover the house, you want to know before the deal is firm.

Asbestos and vermiculite insulation

Health Canada says that “before 1990, asbestos was mainly used for insulating buildings and homes against cold weather and noise.” It may still be found in older building materials. Health Canada’s examples include house siding, cement and plaster as well as floor and ceiling tiles. Health Canada also says vermiculite-based insulation may contain asbestos.

The risk depends on what you plan to do. Health Canada says there are no significant health risks if materials containing asbestos are left undisturbed or sealed behind walls and floorboards. The concern is renovation. It advises you to “hire a professional to test for asbestos before renovating or remodelling” and to hire a specialist to remove it if it is found. If you have vermiculite insulation in your attic or walls, it says not to disturb it or try to remove it yourself, not to use the attic for storage and to keep children out of the attic. It says to hire professionals trained to handle asbestos if you plan to renovate.

If you are buying an older house because you intend to open up the kitchen or finish the basement, price testing and possible removal into your renovation budget before you set your offer price.

Lead water service pipes

The City of Markham says that “before 1953, lead was used as water service line material for residential houses.” It also says that all known lead service lines in Markham, from the municipal watermain up to the property line, have been replaced.

The private side is a different matter. Markham says there could be private service lines from the property line to the house that are made of lead or contain lead. It says the City is only responsible for service lines up to the property line. On a house built before 1953, any lead in that part of the pipe is the owner’s to deal with. Markham encourages residents to replace lead service lines and plumbing on their property.

You can look for yourself on a showing. Markham suggests locating the water meter (typically in the basement) and looking at the pipe coming up through the floor. The City says lead “is grey, does not echo if you gently strike it, scratches easily and leaves metallic marks when you rub the scratched area against paper.” If you suspect a lead service line, the City’s Contact Centre is at 905.477.5530. For lead plumbing inside the house, it says to contact a plumber.

Basement flooding and the City’s plumbing rebate

Look closely at how the basement is protected from flooding. Markham runs the Private Plumbing Protection Rebate Program for measures that reduce the risk of sewer back-up.

Measure	Maximum rebate
Indoor backwater valve, sanitary or storm lateral	$1,750
Outdoor backwater valve, sanitary or storm lateral	$2,000
Weeping tile redirected from sanitary to storm lateral by gravity	$3,000
Weeping tile disconnected with sump pump installed	$5,000
Storm lateral reline or repair	$2,500
Sanitary lateral reline or repair	$2,500

The rules are strict. The property must be in a known flood prone area or show a flood risk in the area. The owner must get approval of the work from the City’s Environmental Services Department before installation. New installations need building permits and City inspections. Downspouts must be disconnected from the City sewer system. The City lists April 30, 2027 as the deadline to obtain the building permit and July 31, 2027 as the deadline for rebate applications.

Markham’s own advice for owners is simple to check on a showing. It says to extend downspouts so they discharge water at least 1 metre from the foundation. It also says to make sure the ground slopes away from the house for a minimum of 1 metre.

Past renovations and building permits

An older house may have been renovated more than once. The City of Markham’s building permit page lists work that needs a permit, including:

• any addition to an existing building, irrespective of size
• adding, removing or altering a structural wall or column
• installing any new plumbing piping
• renovating a dwelling to provide a full basement
• building separate rooms in a basement
• raised decks more than 24 inches above existing grade at any point

The same page lists work that does not need one, such as replacing plumbing fixtures or water heaters, decks less than 24 inches above grade at all locations, painting and decorating as well as maintenance and repairs.

If the basement has been finished into rooms or a wall has come out between the kitchen and dining room, ask the seller whether permits were taken out. For questions about a property, the page lists Markham’s Building Standards Department at 905.475.4858. Ask your lawyer what searches to make before closing.

Heritage districts and mature trees

Markham protects some historic areas as heritage conservation districts. The City lists four: Thornhill, Markham Village, Buttonville and Unionville. Owners there must get approval for “exterior alterations to property, new construction or demolition” through a Minor or Major Heritage Permit application. Staff can approve changes that follow the district’s policies, but demolition requests go to Markham Council. Our post on the Unionville heritage district rules goes through that district in more detail. To check a specific address, the City points to its Register of Property of Cultural Heritage Value or Interest and the district maps.

Our neighbourhood guides to Thornhill, Markham Village and Unionville describe the housing in each area.

Mature trees bring their own rule. Under Markham’s Tree Preservation By-law 2023-164, a permit is needed for a private tree with a trunk diameter of 20 centimetres or more, measured 1.37 metres above ground, “regardless tree health or risk level.” The City reviews applications within 45 days of payment, charges a non-refundable $20.50 processing fee effective January 16, 2026 and may require replacement planting or cash in lieu. Trees on or crossing a property line need the neighbour’s consent. If your plans for the lot include an addition, a pool or a new driveway, check the trees first.

A checklist for older homes in Markham

1. Make your offer conditional on a home inspection and ask the inspector to note wiring type, insulation and the water service pipe.
2. Call your insurer about the wiring before the condition date.
3. Look at the pipe beside the water meter on a house built before 1953.
4. Check downspouts, grading and whether the basement has a backwater valve or sump pump.
5. Ask the seller which renovations had permits and keep their answers in writing.
6. Check the heritage register and the tree by-law if you plan exterior changes.
7. Add testing, rewiring or pipe replacement to your budget if any of these turn up.

Our post on moving from a townhouse to a detached house covers the money side of the step. The upsizing guide explains how we plan a move-up purchase. Our buyer services page covers the search itself. If you have an older Markham house in mind and want help working through these checks, contact us.