Knob-and-tube
Found in early-1900s homes; no ground, brittle insulation, and not made for modern loads.
Aluminum branch wiring
Common 1960s–70s; connections can loosen and overheat. Often remediable with proper connectors instead of a full rewire.
Insurance angle
Many insurers surcharge or refuse these. Documented remediation helps. VERIFY insurer specifics.
Rewiring cost
Quoted by scope; partial remediation is far cheaper than whole-home. VERIFY.