Knob and Tube Wiring Replacement Cost

Full knob and tube wiring replacement costs $8,000 to $36,000, or roughly $8 to $17 per square foot, with sources citing a national average around $24,000 for a typical whole-home job. Partial, per-opening work — rewiring a single outlet, switch, or fixture connection — runs $100 to $350+ per opening, a much smaller commitment if only part of the home still has the original wiring. See our electrical repair cost guide for how this compares to other electrical work.

Cost by scope

The full-replacement range is genuinely wide because scope varies enormously — a straightforward single-story home is far cheaper to rewire than one with finished plaster walls, multiple stories, or difficult attic/crawl space access. Get an in-person quote rather than assuming either end of the national range applies to your home.

Why knob and tube gets flagged

Knob and tube wiring — installed in most U.S. homes built before roughly 1950 — was a reasonable standard for its era, but has three problems by modern standards: it has no ground wire, its insulation degrades and becomes brittle with age, and it's only rated for 60°C versus the 90°C rating of modern wiring and fixtures. Directly connecting modern high-wattage fixtures or insulation packed too close to the exposed wiring can create real overheating risk. Because of this, many insurers require full or partial replacement — or decline to write a policy at all — on homes with active knob and tube wiring, particularly if it hasn't been inspected recently.

Partial replacement vs. full rewire

• Partial (per-opening) replacement makes sense if only specific rooms or circuits still have knob and tube — common when a previous owner already updated part of the home.
• Full replacement is usually the more practical path if most of the home is still original, since per-opening pricing adds up quickly once you're past a handful of openings, and a single whole-home project avoids repeated service calls.

If you're comparing old-wiring problems

Aluminum wiring is a different but related old-home wiring issue, common in homes built about 15-20 years later than typical knob and tube installs — see Cost to Replace Aluminum Wiring With Copper if you're not sure which one your home has. For labor rate context on either job, see Electrician Cost Per Hour: 2026 Rates Explained.

Prices on this page are researched ranges compiled from multiple public contractor-pricing sources, not quotes from us or a guarantee of what you will pay. Actual costs vary by region, material choice, and job complexity — always get itemized quotes from licensed local contractors before committing to a project. See How We Price for our sourcing methodology.

Frequently Asked Questions

How do I know if my home has knob and tube wiring?

Homes built before roughly 1950 are the most likely candidates. It's visually distinctive — ceramic knobs anchoring wires along joists and ceramic tubes protecting wires passing through framing, usually visible in an unfinished basement or attic. A licensed electrician can confirm and assess its condition.

Is knob and tube wiring illegal or automatically unsafe?

It's not automatically illegal, and if properly maintained and not modified or overloaded, it isn't automatically a fire hazard — many code officials permit it to remain if undisturbed and in good condition. The bigger practical issue for most homeowners is insurance: many insurers won't cover a home with active knob and tube wiring regardless of its condition.

Can I add insulation around knob and tube wiring?

No — building and electrical codes generally prohibit packing insulation directly around knob and tube wiring, because the open-air design that keeps it cool depends on that airspace. This is a common reason homeowners discover they have K&T wiring: an insulation contractor flags it before an attic insulation upgrade.

Does removing knob and tube wiring increase home value?

It can help with resale, particularly because it removes an insurance and financing obstacle for buyers — some mortgage lenders and insurers specifically flag active knob and tube wiring during underwriting. It's not typically marketed as a value-adding upgrade the way a kitchen remodel is, but it removes a real friction point in a sale.