CanadaPolitics

To add to this, most land in cities is zoned to only permit one residentual house, maybe a suite or two depending on the municipality and size of the parcel. Any time someone wants to build an apartment or anything other than what's permitted they are required to apply for a zoning amendment and have it approved via council. Rezonings can often take several months to years to go through and depending on who council is and how strong the opposition's voice is, the rezoning may get denied. So it's kind risky, even moreso of you need to apply for an Official Community Plan amendment as well as ask for a bunch of variences to things like setbacks, parking, etc.

If you're curious, your city will have a zoning map available online that your can look at to see how much is zoned to only allow one house. It's generally called Residential 1,or R1, or Low Density Residential or something like that and will coloured light yellow, maybe light blue.