Buying a house with knob-and-tube wiring

Finding knob-and-tube wiring doesn't answer the buying question by itself. You need to establish what is still in use, what condition it's in, what work is recommended and whether an insurer will cover the property on terms you can meet.

Those answers come from different people. A Licensed Electrical Contractor assesses the electrical system. An insurer decides whether it will accept the risk. A favourable answer from one doesn't commit the other.

What exactly has been found?

Start with the wording of the inspection finding. Does it identify active knob-and-tube wiring, visible remnants, or suspected wiring that requires further assessment? Ask where it was observed and request the associated photographs.

The Electrical Safety Authority describes knob-and-tube as a wiring method used in homes in the early 1900s through the 1940s. The age of a house may explain why someone is looking for it, but age alone doesn't establish what's connected today.

If the seller says the house was rewired, find out what that work covered. A statement that electrical work was completed doesn't identify every remaining circuit. Give the contractor any available invoices, scope descriptions and electrical inspection records, alongside the home inspector's observations. Ask the contractor to distinguish what was confirmed from what remains inaccessible or unknown.

Does it automatically make the house unsafe?

ESA's guidance says knob-and-tube can be safe when properly maintained by a Licensed Electrical Contractor. It also says these older systems lack the same safety benefits as modern ones and recommends an electrical assessment for a home with this wiring.

Both parts matter. The conditional reassurance on a public information page is not an assessment of the house you're buying. Equally, identifying the wiring method doesn't tell you the condition of every conductor.

Ask the contractor to explain any deterioration or damage found, the recommended response and its urgency. If an immediate hazard is identified, follow the contractor's safety directions; don't keep testing outlets or opening electrical equipment yourself to investigate it.

Isn't a home inspection enough?

ESA specifically distinguishes the electrical assessment from a home inspection: the Licensed Electrical Contractor focuses on the electrical system and can examine knob-and-tube conductors for deterioration or damage.

Use the home inspection to define the questions for that assessment. Ask for a written description of the areas examined, what was accessible, the findings and the limits of the work. If concealed wiring remains uncertain, find out what further investigation would be required and whether the seller will permit it.

The goal isn't a reassuring adjective such as “good.” It's an explanation you and the insurer can use: what is present, what the contractor found, what should change and what hasn't been established.

Will an insurer cover it if the contractor says it's in good condition?

Possibly, but don't assume so. ESA warns that many insurers will not provide or renew coverage for homes with knob-and-tube, and some may require replacement before providing coverage.

Contact your broker or prospective insurer while you still have time to act on the answer. Describe the finding accurately. Ask what information it needs, whether it will insure the property in its existing condition, when coverage could begin, and whether any work or further assessment is a condition of that coverage.

If replacement is required, establish the timing and evidence the insurer will accept. “We'll have it dealt with after moving in” may not meet a requirement for work before coverage starts. Have the broker confirm the actual terms in writing; a contractor's opinion or an inspection document does not override an insurer's underwriting decision.

The seller's existing insurance isn't a commitment to insure you. If you're financing the purchase, also ask your lender what insurance evidence it requires and when.

Is all old wiring legally required to be replaced?

Don't infer a legal obligation from its age alone. ESA's knob-and-tube guidance says the Ontario Electrical Safety Code is not retroactive. For new work, ESA identifies the 2024 edition of the Code as effective May 1, 2025; requirements for a particular installation need to be established under the applicable rules.

Have the Licensed Electrical Contractor identify the requirements applicable to the actual work, including the necessary ESA notification and inspection process. Keep that question separate from an insurer requiring replacement as a condition of coverage. The insurer's condition can affect whether you can complete the purchase even when the mere presence of older wiring hasn't established a blanket legal replacement requirement.

How do I get a repair estimate worth using in an offer?

Arrange access for the contractor before asking for a firm scope. Then request an itemized estimate explaining the circuits or areas included, any further investigation, access assumptions, and what happens if additional wiring is found.

Make restoration explicit. Who opens walls or ceilings if needed? Who patches and paints afterward? Are those costs included, separately priced or excluded? Also ask about scheduling, power interruptions and whether the proposed sequence fits the insurer's conditions.

Compare quotes on the same scope. A limited repair and a full replacement can produce different prices because they promise different work. There is no useful universal cost figure to apply to an unassessed house, and a discount from the seller doesn't arrange the contractor or secure insurance.

When is proceeding a reasonable choice?

When you understand the findings, can obtain the necessary coverage and financing, and can afford and accommodate the agreed work—including the uncertainty still identified in the estimate.

If those answers aren't available before you would become unconditionally committed, discuss review time and appropriate conditions with your lawyer. You may decide the house is worth pursuing, negotiate around a defined scope, or leave it. The wiring label starts the investigation; the condition, insurability and practical repair plan determine whether the purchase works for you.