Knob & Tube Rewiring
Cloth-wrapped wire in a house that predates the wiring code
St. Charles has Missouri's largest historic district, and plenty of homes in Old Town and Frenchtown still have some original knob and tube in the walls. It is not automatically an emergency. It is also not something to leave alone forever.
- Old Town and Frenchtown homes
- Staged or whole-house replacement
- Insurance and inspection documentation
- Historic district work handled carefully
What it is
Why knob and tube is a problem now and was not in 1925
The wiring was competent for the house it was installed in. The house has changed since.
No ground
Knob and tube is a two-wire system with no equipment ground. Every outlet on it is a two-prong outlet, and nothing downstream is grounded.
Insulation kills it
The system relies on air around the conductors to shed heat. Blown-in or batt insulation added later traps that heat against cloth-wrapped wire.
Sixty years of splices
Almost none of these systems are original anymore. They are original wire spliced into by a succession of people, and the splices are where trouble starts.
For the full background, read our guide to knob and tube wiring before you decide anything.
Why it matters
Why homeowners finally deal with it
Insurance
Some carriers will not write a policy on a home with active knob and tube, and others charge more. A documented replacement resolves that conversation.
Selling
It comes up in every inspection. Handling it before listing is worth more than negotiating over it after.
Safety
Brittle insulation, ungrounded circuits and decades of amateur splices are a genuine fire risk, and the risk grows rather than shrinks.
Actually usable circuits
Two-prong outlets and 15 amp circuits do not fit modern life. Rewiring is also when you get grounded outlets where you need them.
How we approach it
All at once, or in stages
In an occupied historic home, staged replacement is usually the more livable answer.
A full rewire is cleaner and cheaper per circuit, but it means opening a lot of plaster and living around it. Staged replacement takes the highest-risk circuits first — kitchen, bath, anything under insulation, anything feeding a bedroom — and leaves lower-risk runs for later. That spreads the cost and the disruption. Either way we fish through existing cavities wherever possible rather than opening walls by default, which matters a great deal in a house with original plaster and trim you cannot replace. If your property sits in a historic district, exterior work may also involve design review, and we will tell you that up front rather than after.
How we work
What to expect when you call
- 01
We map what is actually live
A lot of knob and tube in these houses is abandoned in place. Knowing what is still energized changes the scope substantially.
- 02
Scope and staging plan
Full rewire or staged, in what order, with a number for each phase so you can decide how fast to go.
- 03
Rewire, inspect, patch
New circuits run and terminated, inspection passed, and access openings patched. We tell you up front what we patch and what a plasterer should.
Free estimate
Get a knob and tube assessment
Tell us the year the house was built and whether you have two-prong outlets. That is usually enough to know what we are walking into.
Related: knob and tube explained, whole-home rewiring, rewiring cost, wiring a historic home, panel upgrade
Something electrical that is not getting better on its own?
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