Knob & Tube Rewiring in Scarborough

Small bungalow (1,000–1,400 sq ft, partial K&T): $8,000–$12,000. Standard semi or small detached (1,500–2,000 sq ft, full K&T): $12,000–$18,000. Larger detached or 2.5-storey Edwardian (2,500–3,500 sq ft, full K&T): $18,000–$25,000+. Includes ESA-permitted rewiring, drywall/plaster repair, paint, baseboard replacement, fixture re-install, and ESA Form 1. Panel upgrade often pulled into scope: +$2,500–$5,500.

Most major Canadian insurers (Aviva, Intact, TD, Wawanesa, Co-operators, Economical) refuse to renew policies on properties with K&T circuits exceeding 10–15% of wiring inventory, and require full removal within 30–90 days of policy notice. The reason is documented failure-mode risk: 90–120-year-old rubber/cloth insulation degradation, connection oxidation, modern-appliance load mismatch, and rodent damage. ESA Form 1 (Certificate of Inspection) issued after rewiring satisfies the insurer.

ESA Form 1 is the Certificate of Inspection issued by the Electrical Safety Authority after passing final inspection of permit-pulled work. Insurers require this document as proof that the rewiring was done by ECRA-licensed personnel and inspected to Ontario Electrical Safety Code standards. RenoHouse delivers Form 1 plus a project-completion package within 5 business days of final inspection.

Some insurers accept partial removal (down to 0% active K&T) but most now require full removal of all active circuits — the 10–15% threshold has dropped to zero with several carriers in 2025–2026. Confirm with your insurer's underwriter before quoting partial scope. RenoHouse defaults to full-house rewiring because the partial-scope cost savings rarely exceed the cost of having to come back later for the rest.

A full-house K&T rewire requires 30–50 wall and ceiling openings (6"x10" to 12"x18" each) to route NMD-90 cable from outlet to junction to switch to fixture. In plaster homes (most pre-1950 Scarborough stock) the patches are harder — cuts must respect lath spacing, patch material must bond to existing lath, and texture/finish must match. We default to skim-coating affected walls when more than 4 patches are needed in a single room. Drywall/plaster repair often costs more than the wiring itself on K&T jobs.

Yes — strongly recommended. Every drywall patch made for the rewiring becomes 'free' (already in the renovation scope), and the renovation timeline absorbs ESA inspection holds. Combined K&T rewiring + room renovation is 25–35% cheaper than rewiring done alone followed by a renovation 12 months later. We sequence both projects under one contract with one set of permits where possible.

Yes — RenoHouse holds Master Electrician licensing and an ECRA/ESA contractor license. All electrical work is performed under ECRA-licensed personnel, with ESA Permits pulled by the Master Electrician of record. Drywall/plaster repair, paint, baseboard, and finish work is performed by RenoHouse trades. The customer has one point of contact for the entire project.

Pre-1980 plaster walls in older Scarborough homes may contain asbestos in the finish coat or joint compound. When wall openings exceed Type 1 thresholds (~1 m² per opening), we coordinate with HCRA-licensed Type 1/2 abatement specialists before continuing rough-in. Asbestos abatement is performed by certified specialist (we do NOT remove asbestos in-house) — see our Asbestos Abatement Coordination page.

Smaller homes (1,000–1,400 sq ft): 5–8 business days for rough-in + drywall/plaster repair, plus 3–5 days for paint and finish. Standard semi or small detached: 8–12 business days. Larger detached or 2.5-storey Edwardian: 12–18 business days. ESA inspections (rough-in and final) add 2–5 business days each in scheduling. Total project clock: 3–6 weeks from contract to ESA Form 1, depending on scope and inspector availability.

Most homeowners stay in place during smaller-scope rewires — work proceeds room-by-room with electrical supply maintained on rotating circuits. Larger full-house rewires sometimes benefit from 1–2 weeks of vacancy during rough-in if the homeowner has elderly residents, infants, or asthma sensitivity to plaster dust. We discuss case-by-case at the site visit. Power is never fully cut for more than 4–8 hours at a time.

If your older home still has a 100-amp panel, upgrading to 200 amps is highly recommended — especially if you're adding major appliances, EV chargers, or renovating. Modern homes draw significantly more power, and the upgrade future-proofs your electrical system while improving safety.

Knob-and-tube wiring isn't inherently dangerous when undisturbed, but it lacks grounding, can't handle modern electrical loads, and becomes hazardous when insulation is added around it. We recommend replacement during any renovation that opens walls — it also improves your home insurance eligibility.

Yes, but it requires careful cutting to avoid cracking the surrounding plaster. We use specialized techniques to install recessed lighting in plaster ceilings, and can run new wiring through the ceiling cavity from above. The result is modern lighting without damaging your home's character.