Knob-and-tube wiring and homeowners insurance

Why insurers care

Many insurers will not write or renew a homeowners policy on a house with active knob-and-tube wiring, and the ones that will often require an inspection or a remediation timeline first. Knob-and-tube is not automatically unsafe if it was installed well and left alone, but it has no ground, it was never designed for the loads a modern house pulls, and its insulation is often brittle after decades. Insurers treat all of that as a fire risk, and it comes up constantly in older Portland neighborhoods.

This is one of the most common ways homeowners even find out they have it: at renewal, or during the sale of a pre-1950 home. If a policy or a closing is hanging on it, dealing with the wiring is what clears it.

What knob-and-tube actually is

Knob-and-tube was the standard wiring method in American homes from roughly the 1880s into the 1940s, so plenty of Portland's older housing stock still has some. You can recognize it in a basement or attic: single wires run through the framing, held away from the wood by white ceramic knobs and passed through joists inside ceramic tubes. It has two defining limitations that drive the insurance concern.

• No ground wire, so there is no safe path for a fault and no grounding for modern three-prong devices
• Original rubber-and-cloth insulation that dries out, cracks, and flakes off after 70-plus years
• It was sized for lamps and a radio, not today's kitchens, HVAC, and electronics

The real danger: buried in insulation

Here is the part that turns old-but-stable wiring into a genuine hazard, and it is specific to knob-and-tube. This wiring was designed to run through open air, which lets the heat it makes dissipate. When a house is later insulated, and blown-in or batt insulation gets packed around the wires in the attic and walls, that heat has nowhere to go. It builds up, cooks the already-brittle insulation, and that is where fires start. A lot of Portland homes had insulation added decades after they were wired, so this pairing is common here, and it is exactly what an inspector and an insurer worry about.

What insurers usually want

Requirements vary by carrier, but they tend to land in a few places. Knowing what they will ask for helps you get ahead of it.

• An inspection and a written evaluation of the wiring's condition from a licensed electrician
• Full or partial replacement of the active knob-and-tube, sometimes on a set timeline after purchase
• Confirmation that no live knob-and-tube is buried in insulation
• A letter documenting the work once the wiring has been remediated

Your options and what's next

You do not always have to rewire an entire house at once. Where the knob-and-tube is limited to certain circuits, a partial rewire that replaces the active runs, especially anything buried in insulation, can satisfy an insurer. Where it is throughout the home, a full knob-and-tube rewire is the permanent answer and resets the clock on the house's electrical system. Either way it is permitted, inspected work, and it usually gets paired with grounded outlets and often a panel upgrade, since old K&T homes frequently have an undersized service too.

If you are buying, selling, or facing a renewal, start with an evaluation so you know how much is active and where it runs. We assess it, give you a free ballpark by phone once we know the scope, and provide the documentation your insurer needs. Aluminum branch wiring raises similar insurance questions, and if your home has both, our guide on aluminum wiring covers that side.