Home Insurance for Homes With Knob-and-Tube Wiring

You found a beautiful older home — hardwood floors, high ceilings, built in 1920. You make an offer, it's accepted, and then your insurance agent drops the news: the house has knob-and-tube wiring, and most carriers won't touch it.

Welcome to one of the more frustrating realities of insuring older homes.

Here's what knob-and-tube wiring actually is, why insurers care so much about it, and what you can do about it.

What Is Knob-and-Tube Wiring?

Knob-and-tube (KAT) wiring was the standard electrical system in American homes from roughly the 1880s through the 1940s. The "knobs" are ceramic insulators that hold the wires away from wood framing; the "tubes" are ceramic sleeves that protect the wires where they pass through joists or studs.

At the time, it was perfectly fine technology. The problem is that electrical loads in a modern home — central AC, dishwashers, EV chargers, a house full of devices — are orders of magnitude heavier than what those systems were designed to handle. When old wiring gets overloaded, it overheats. And when it overheats inside a wall or attic, house fires happen.

There's another wrinkle: KAT wiring is ungrounded, meaning there's no third wire to safely redirect a fault. That's why your plugs in older homes only have two prongs. No ground means higher risk for electrical surges damaging appliances — and for shock or fire.

Why Insurance Companies Get Nervous

Insurers price risk. Homes with knob-and-tube wiring have a higher documented risk of electrical fires, and that shows up in claims data. A carrier taking on a KAT home is essentially writing a policy on a property with a known hazard they can't fully control.

The responses vary by carrier:

Flat denial. Many standard home insurers won't write a policy at all if KAT wiring is present throughout the home.
Higher premiums. Some carriers will insure the home but charge significantly more — sometimes 20–30% above what a comparable home with updated wiring would cost.
Coverage with conditions. A carrier might issue a policy but require you to replace the wiring within 30, 60, or 90 days or face cancellation.
Partial coverage. Some policies will exclude electrical-related fire claims, which largely defeats the purpose.

The situation can catch buyers off guard. You might close on a home, get a policy issued, and then receive a cancellation notice six months later after an inspection or underwriting review. That's a bad surprise.

How to Find Out If Your Home Has It

If your home was built before 1950, there's a real chance it still has some KAT wiring. Here's how to check:

Look in the attic or basement. If you see wires running between ceramic knob insulators and passing through ceramic tubes in joists, that's KAT.
Check your breaker panel. Old fuse boxes (especially round screw-in glass fuses) are often a sign the electrical system hasn't been updated.
Hire a licensed electrician for a proper inspection. A home inspector can flag it, but an electrician can tell you the scope — whether it's the whole house or just a section — and give you a realistic estimate for replacement.

Don't guess. Knowing what you're actually dealing with is the foundation for every decision that follows.

Your Options as a Homeowner

Option 1: Full rewire

This is the cleanest solution. A full electrical rewire replaces the KAT with modern Romex (NM) wiring, installs a proper panel, and brings the home up to current code. Most insurance companies will accept the home normally once you can provide documentation — typically a certificate of completion from the electrician or a passed city inspection.

Cost? Realistically $8,000–$20,000+ depending on the size of the home, your location, and how much of the original wiring needs to come out. It's a real number, but it's also a permanent fix.

Option 2: Partial replacement

If only part of the home has KAT wiring, you may be able to replace just those sections and satisfy an insurer's requirements. A licensed electrician can tell you whether this is feasible or whether the scope of work makes a full rewire more practical anyway.

Option 3: Specialty or non-standard insurance

Some carriers specialize in older or historic homes and are more willing to write policies with KAT wiring present — particularly if the wiring is in good condition, hasn't been modified (more on that below), and the home has other updated safety features like a modern panel, GFCI outlets, and smoke/CO detectors.

Expect to pay more, and read the policy carefully. Make sure electrical fires aren't excluded.

Option 4: Work with an independent broker

This is probably the most underused option. An independent insurance agent can shop your home across dozens of carriers, including specialty markets that don't advertise widely. If you've been declined by one or two big-name insurers, that doesn't mean you're out of options — it means you need a broker who knows where to look.

The Modified Wiring Problem

Here's a hidden danger specific to KAT systems: improper modifications. When someone in the 1970s or 80s decided to add a circuit by splicing modern wiring into the old KAT system, they often did it incorrectly — without proper junction boxes, inside insulation, or in ways that create heat buildup.

Inspectors and insurers sometimes treat modified KAT as a bigger problem than untouched KAT, because the original system was at least installed by professionals working to the standards of their day. Hacked-together additions are a wildcard.

If your KAT system has been modified, you should have an electrician evaluate those specific areas carefully. That's also information to have before you talk to an insurer.

What to Tell Your Insurance Agent

When you're shopping for coverage on an older home, be upfront. Provide:

The year the home was built
The results of any electrical inspection you've had
The scope of KAT wiring (whole house vs. partial)
Any updates already made (new panel, partial rewire, GFCI outlets)
The condition of the wiring based on an electrician's assessment

Hiding it doesn't help. If a carrier discovers undisclosed KAT wiring after a claim, they may deny the claim or rescind the policy. Transparency upfront puts you in a much better position.

The Bottom Line

Knob-and-tube wiring makes home insurance harder, but it doesn't make it impossible. Your path depends on the scope of the wiring, your budget, and how motivated you are to rewire versus how willing you are to work in specialty markets.

If you're buying a home with KAT wiring, factor the cost of rewiring into your offer and negotiation. It's a real cost, and it affects your total outlay on the home.

If you already own the home and are running into insurance problems, start with a licensed electrician's assessment. Then talk to a broker who understands older homes — not just whoever's running ads online.

At Truvo, we work with homeowners in exactly these situations. If you've been declined or are having trouble finding affordable coverage for an older home, get a quote and let us find carriers who can actually help. You shouldn't have to navigate this alone.