A house built before 1950 is 77 to 126 years old. Houses from this period were built before most of the wiring, plumbing and insulation rules people now take for granted, so what matters is far less the age of the building than what has been replaced since, and by whom. Here is what holds across the whole era, what changes depending on the exact year, and what each one costs.
These apply whether it was built in 1900 or 1949. Ages are counted to 2026.
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 77 to 126 years old, if they are original
A house built in 1900 is 126 years old and one built in 1949 is 77, 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.
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?
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, to remove, 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?
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 to the house in front of you.
Every dollar figure on this page comes from the Casaroo repair cost dataset, published openly with its methodology, version and licence. Each item links to the guide that lists its own sources. Figures are 2026 Canadian dollars and are ranges, not quotes.
The year is what changes the answer. Pick it and you get the specific read.
Built from the Casaroo knowledge base in 2026. Ages on this page are counted to 2026. Educational and impartial, not a home inspection.