What is behind the walls of an older house

Knob-and-tube wiring was the standard method in American houses into the 1930s. Individual conductors run separately, held off the framing by ceramic knobs and passed through joists in ceramic tubes, with cloth and rubber insulation. Plenty of Park Hill homes have been partly or fully rewired, but sections often survive in attics, upper walls and ceilings, sometimes spliced to newer circuits.

The system was designed to shed heat into open air. Fire changes that in a hurry. Heat can make the old rubber insulation brittle or burn it off; attic insulation blown in over the wires traps heat; water from firefighting soaks the cloth wrap and reaches splices that were never meant to get wet. None of that is visible from a light switch.

Later wiring has its own problems after a fire. Early cloth-sheathed cable, ungrounded circuits and overloaded fuse boxes are common in older houses, and a fire is often the first time anyone has looked closely at them in decades.

How the electrical decision usually goes

  • IfWiring in the fire area is visibly burned or wetThose circuits are typically replaced. Expect the electrician to trace them back to the panel.
  • IfKnob-and-tube runs through walls that will be opened anywayThis is the cheapest moment to replace it, since access is the expensive part of rewiring.
  • IfOld wiring is far from the fire and looks undamagedAn electrician may test and leave it, but your insurer may have its own view on older wiring; ask before closing walls.
  • IfThe panel is a fuse box or an outdated breaker panelAsk whether the repair requires or would benefit from an upgrade, and whether code updates are covered under your policy.

Questions for the electrician and the adjuster

  1. Which circuits were damaged by heat or water, and how did you test them?
  2. Is there knob-and-tube or cloth-sheathed wiring in walls that are being opened?
  3. Will the repair need a Denver electrical permit and inspection, and who pulls it?
  4. Does code require new circuits, outlets or smoke alarms as part of this repair?
  5. Does my policy include ordinance or law coverage for required upgrades?
  6. Can the rewiring be scheduled before plaster patching, so walls are not opened twice?

While you wait for clearance

General information for Park Hill, not a quote or professional advice. In an emergency, call 911.