Knob-and-tube wiring and home insurance: what Grand Rapids owners need to know

Why knob-and-tube worries insurers

Knob-and-tube was installed in houses built before about 1950. It has no ground conductor, its insulation becomes brittle with age, and it was designed to shed heat into open air. The problems come later: attic insulation blown over it, modern cable spliced into it without boxes, and loads far heavier than it was built for.

In Grand Rapids, where more than a third of homes were built before 1940 and the median house dates to 1953, knob-and-tube still turns up in Heritage Hill, Eastown, Creston and Alger Heights. Insurers know this, which is why the question comes up at renewals and home sales.

Live versus abandoned

Many houses have old knob-and-tube in the walls that was disconnected decades ago when the house was partly rewired. That is not usually a problem for insurers. What matters is whether any of it is still energized. The only way to know is to trace circuits from the panel and test the old runs for voltage in the attic and basement.

The result should be a room-by-room map of which circuits are live knob-and-tube, which are abandoned, and where old wiring was extended with newer cable. That map is what the insurer, the inspector and the price all work from.

What replacement involves

Active circuits are replaced with modern grounded cable, usually fished through walls from the attic and basement so most plaster stays intact. The old runs are disconnected and labeled as dead. Where a house has only a few live circuits, a partial knob-and-tube replacement is quicker and cheaper than a full rewire; where most of the house is original, a staged whole-house rewire is usually the better value.

Regional removal is often around $5,000 before any panel work, and whole-house rewiring commonly runs $8,000 to $20,000. The panel often changes too, because the new grounded circuits need space and capacity an old panel lacks.

Attic insulation and the order of work

Insulation must not be packed around active knob-and-tube, because the wire relies on open air to cool. That means the attic runs usually have to be replaced before an attic can be insulated. Planning the order saves money: electrical first, using the open attic to fish new cable, then insulation.

What to give your insurer

Insurers generally want to see the permit, the inspection sign-off and a written record showing which circuits were replaced and that no active knob-and-tube remains. Ask the insurer exactly what they need before work starts, and whether they have a deadline, so the stages can be planned to meet it.

Ask for the scope in writing, listing which circuits will be replaced and which stay, so your insurer gets a clear answer.