Blind spots by year

What to look for in a house built in 1946

A 1946 build is 80 years old. A house from before about 1950 was wired with knob and tube, and that is the item most likely to come up when a policy is being arranged. Here is what tends to be true at that age, what each one costs in 2026 Canadian dollars, and the sentence to say to the agent.

Three blind spots in a 1946 house

Ordered by what tends to matter most.

Worth knowing before you go firm

Knob and tube wiring

Homes built before about 1950 were wired with knob and tube. It has no ground, the insulation goes brittle with age, and it is not safe buried under added insulation. It is the era item most likely to come up when a policy is being written.

If the panel needs replacing as part of resolving it, that is $1,500 to $4,000, plus the Hydro disconnect and the ESA permit on top.

Knob and tube shows as single cloth covered wires running through white ceramic knobs and tubes, usually visible in a basement ceiling or an attic. A photo of the open panel and one of the basement ceiling will usually settle it.

Say this to the agentIs any knob and tube wiring still live in this house, and if it has been removed is there paperwork for the work?

The systems are 80 years old, if they are original

The building is 80 years old, and so is every system in it that has never been replaced. That is the part a listing photo cannot show you, because a replaced furnace and an original one look identical from the doorway.

The water heater lasts 8 to 12 years. An original one here is past that, and replacing it is $1,800 to $2,800, in Ontario if the tank is owned, and a great many Ontario tanks are rentals.
The air conditioner lasts 10 to 15 years. An original one here is past that, and replacing it is $4,500 to $9,000, in Ontario, or $3,500 to $6,500 if only the condenser is replaced.
The furnace lasts 15 to 25 years. An original one here is past that, and replacing it is $3,500 to $8,500, in Ontario, and $5,500 to $10,500 for a high efficiency unit.
The roof lasts 20 years for a 3 tab asphalt roof and about 30 for architectural shingles. An original one here is past that, and replacing it is $8,000 to $18,000, a GTA re-roof, more for steep or multi layer roofs.

All of these carry a date. The water heater has a rating plate near the top of the tank, usually with the date encoded in the serial number, and the furnace and the air conditioner both carry a dated label. Photograph them.

Say this to the agentHow old is the water heater, and is it owned or rented? Has the air conditioner been replaced, and if so when? How old is the furnace, and has the heat exchanger ever been checked? When was the roof last done, and is there paperwork for it?

Worth knowing before you go firm

A buried oil tank, if this house ever had oil heat

Homes heated with oil before about 1975 often had the tank abandoned in place when they converted to gas rather than removed. A leaking buried tank is an environmental problem rather than a repair, and it is the single item in this list most likely to stop a policy being written until it is resolved.

Removal runs $1,800 to $3,000, with soil remediation commonly $5,000 to $15,000 and documented cases far beyond that.

Look for a fill pipe or vent stub poking out of an exterior wall, and for capped copper fuel lines at the basement wall. If the listing says converted to gas, the question is whether there is removal paperwork.

Say this to the agentWas this house ever heated with oil, and if it was, is there a record of the tank being removed and the soil tested?

Six more that come with a house this age

Galvanized steel supply pipeWhat are the supply pipes made of, and how much of the original pipe is still in the walls?

An undersized electrical serviceWhat is the service amperage, and has the panel ever been upgraded?

A lead water service line or lead solderWhat material is the water service line, and has the city replaced its side of it?

Lead paint under the newer coatsHow much of the original trim and how many of the original windows are still in place?

Era materials that can contain asbestosIs there any original pipe wrap, vinyl floor tile or textured ceiling left, and has any of it ever been tested?

UFFI, if this house was ever foam insulatedHas this house ever been tested for UFFI, and is there a declaration about it in the paperwork?

This is what is typical for the year. It is not a finding about this house.
Photographs of the panel, the basement and the water heater would tell you whether any of it applies here.

Worth ten minutes each

Is Knob and Tube Wiring a Dealbreaker? Homes Insurers Will Not Cover in Canada Is an Oil Tank a Dealbreaker?

Built from the Casaroo knowledge base in 2026. Ages on this page are counted to 2026.