Rewiring
Knob and Tube and Aluminium Rewiring
The two wiring types insurers refuse. One is pre-1950 and brittle, the other is mid-1970s and loosens at every connection.
Two wiring systems get houses declined at renewal in Ontario, and they are from opposite ends of the last century. Knob and tube is pre-1950. Aluminium branch wiring is roughly 1965 to 1978. Neither is unsafe in the abstract, and both are treated as unsafe by underwriters, which amounts to the same thing for the person holding the policy.
Knob and tube
It is an open-air system: conductors run separately through porcelain knobs and tubes and rely on the air around them to shed heat. That works until somebody insulates the attic, at which point the wiring is buried in exactly what it was designed not to be buried in. In this region a great deal of pre-war housing has been insulated once or twice since, and the two decisions were never made together.
It also has no equipment grounding conductor, which is why every outlet in a knob-and-tube house is a two-prong one, and why the three-prong adaptors people fit are worse than the problem they solve.
Aluminium branch wiring
Aluminium is a perfectly good conductor. The failure is at the terminations: it expands and contracts more than copper, it creeps under a screw, and it oxidises into a resistive layer. Every one of those effects concentrates heat at the connection rather than in the wire, which is why aluminium problems show up at outlets, switches and panel lugs and almost never mid-run.
Full rewire, or remediated connections
Aluminium has an accepted middle path that knob and tube does not. Insurers will frequently accept properly remediated terminations — approved connectors at every device and junction, done throughout — rather than a full rewire. It is a fraction of the cost. Whether your insurer accepts it is a question to ask before booking anything, because the answer differs between them.
How this is usually staged
A full rewire of an occupied house is disruptive and rarely happens in one visit. The common sequence here is the panel and service first, then the circuits that carry the heaviest load, then the remainder — with the ESA notification covering the whole scope so the eventual inspection signs off a complete job rather than three partial ones.
Talk to a Midland electrical contractor
Tell us the town, roughly when the building was put up, and what the panel looks like — fuses or breakers, and the number on the main. Those three things decide whether you are looking at an afternoon, a scheduled job, or a conversation with your distributor first, and they are usually enough to price it without anybody driving anywhere.