Knob-and-Tube Wiring: Costs, Insurance Issues, and Replacement Options
Why insurers refuse to cover homes with knob-and-tube — and what it costs to bring an old house up to modern code.
Knob-and-tube (K&T) wiring was installed in U.S. homes from roughly 1880 to 1940. It's not inherently dangerous when undisturbed and properly maintained — but most insurers now refuse to write new policies on homes with active K&T, making replacement a near-requirement at any sale.
Why insurers won't cover it
K&T was designed for an era of 30-amp service and a handful of lightbulbs per home. Modern loads regularly overheat the original conductors, and well-meaning DIY work over the decades has often buried the wiring in insulation — exactly what the original design forbids.
Major insurers including State Farm, Allstate, and Liberty Mutual either decline to write or require remediation within 30–60 days of binding. Specialty insurers (Foremost, etc.) will write, often at 30–50% premium.
Replacement cost realistically
Partial replacement (just the active K&T circuits, leaving abandoned runs in place): $4,000–$12,000 on a 1,500 sq ft home. Full whole-house rewire: $8,500–$18,500 on the same footprint. Plaster walls and ceilings push the high end; modern drywall the low end.
Plan on 2–3 weeks of work and a significant amount of patch-and-paint after. Many homeowners coordinate rewires with a kitchen or bath remodel to share the wall-opening cost.