What knob & tube actually is
Knob-and-tube (K&T) is the original residential wiring method: individual copper conductors running through ceramic knobs and tubes, air-cooled, with no grounding conductor. Installed well, it served for decades — which is exactly the problem, because "decades" have now passed. The rubberized insulation on the conductors grows brittle with age and heat; renovations splice new circuits onto old runs; and blown-in attic insulation buries wiring that was designed to shed heat into open air.
Why underwriters care
Three reasons, all boring and legitimate. No ground — modern appliances and surge conditions assume a grounding path K&T doesn't have. Aged insulation — brittle conductor insulation raises fault risk in exactly the places nobody looks. Concealment — under attic insulation, overheating has nowhere to go and inspection is hard. Carriers respond across a spectrum: some preferred programs require full remediation before binding, others accept homes with limited, inspected K&T remaining, and specialty/E&S markets price it as found. Electrician-certified condition reports move homes along that spectrum.
The disclosure duty
Wiring type is a direct application question — our wizard asks it with a "not sure" option, and "not sure" on a pre-war home means we help you find out. Guessing "copper/modern" on a K&T house isn't optimism; it's a misrepresentation that can surface at inspection or, far worse, during a fire claim. Disclosed properly, K&T homes get placed every week. What inspections check →
The remediation path
Full rewire is the gold standard: K&T circuits replaced with modern grounded wiring, permitted and inspected, usually alongside a panel upgrade since pre-war service rarely fits modern loads. It's disruptive (walls open) and it's also the single biggest jump an old home's insurability can make in one project. Partial remediation — rewiring accessible areas (attic, basement) and certifying what remains — satisfies some carriers, particularly with a clean electrician's report. Two cautions: splices between old and new wiring are where problems concentrate, so insist on permitted work; and if blown-in insulation is planned for energy reasons, the wiring conversation comes first.
Pre-war home?
Answer the wiring question honestly — we know who writes K&T.
Four minutes to an indication routed to the markets that fit your home as it stands, plus the remediation math if you want it.
Get a pricing indication →Buying or selling a K&T home
Buyers: get the electrical section of the inspection report early, and get insurance quotes before contingencies lift — wiring is one of the facts that decides which markets will quote at all, and escrow timelines don't enjoy surprises. The buyer's timeline → Sellers: an electrician's certification or a completed rewire is a marketing asset; an undisclosed K&T discovery late in escrow is a renegotiation. Either way, the home is insurable — the only question is which tier, at what price, with what conditions. The older-home playbook →
Frequently asked
Is knob & tube illegal?
Existing, functioning K&T is generally permitted to remain; the constraints come from insurers and from code requirements when you renovate. We're describing underwriting reality, not giving legal or electrical advice — your electrician and local code authority govern the specifics.
How much does a rewire change my premium?
It varies by carrier and home — the honest headline is market access more than any single discount: full remediation moves a home from restricted markets toward preferred ones, and that jump is usually the money. The levers, ranked →
My K&T was "mostly removed" years ago. What do I tell the wizard?
Pick "mixed" and say so — then let an electrician confirm what remains. Partial truth documented beats confident wrong answers, and carriers have programs for exactly this middle ground.