How much does it cost to replace knob and tube wiring in a Saint John heritage home?

Replacing knob and tube wiring in a Saint John heritage home typically costs $15,000 to $35,000 for a complete rewire, depending on the size of the home, accessibility of the walls and attic spaces, and whether you need to open up finished walls and ceilings to pull new wire.

Saint John has one of the oldest housing stocks in New Brunswick, with many beautiful heritage homes in neighbourhoods like Uptown, the South End, and Millidgeville that still have original knob and tube wiring from the early 1900s. While this wiring was perfectly adequate when installed, it was designed for a fraction of the electrical load modern homes demand — and after 80 to 120 years, the cloth insulation deteriorates, becomes brittle, and creates fire hazards.

The biggest cost factor is accessibility. In a home where walls are open (during a renovation) or accessible through an unfinished attic and basement, an electrician can pull new Romex wire through the structure relatively efficiently. But in a fully finished heritage home with plaster walls, hardwood trim, and decorative details you want to preserve, the electrician needs to use creative routing techniques — fishing wire through wall cavities, running wire through the attic and basement to avoid opening walls, and sometimes cutting small access holes that are patched afterward. This labour-intensive approach significantly increases the cost.

A typical price breakdown for a 2,000 square foot Saint John heritage home:

• Complete rewire with new 200 amp panel: $18,000 to $30,000
• Panel upgrade only (if wiring is being done in phases): $2,500 to $4,000
• Per-circuit knob and tube replacement: $400 to $800 per circuit
• Patching and finishing (if walls are opened): $2,000 to $5,000 additional

Insurance is often the trigger. Many New Brunswick insurance companies will not insure a home with active knob and tube wiring, or they'll charge significantly higher premiums. If you're buying a heritage home in Saint John with knob and tube, your insurance company may require remediation within a specific timeframe. Some homeowners address this in phases — replacing the most critical circuits first (kitchen, bathroom, bedrooms) and completing the rest over time.

TSANB permits and inspections are required for any knob and tube replacement. Your electrician will pull the permit and schedule inspections at key stages. For heritage homes, the electrician should be experienced with older construction — plaster and lath walls, balloon framing, and the quirks of 100-year-old buildings. Not every electrician has this experience, so ask specifically about their heritage home work.

One important note about insulation. If your Saint John home has had blown-in insulation added to the walls or attic (very common in older Maritime homes trying to reduce heating costs), and the insulation is in contact with knob and tube wiring, this is an immediate fire hazard. The wiring was designed to dissipate heat in open air — covering it with insulation traps heat and can cause the deteriorated cloth insulation to ignite. This situation should be addressed urgently.

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