Yes, we should absolutely do that too. Calgary is going to vote on blanket rezoning all single-family housing area to allow 4-plexes (with additional basement suites), for example.

I guess the "simple" solution, looking at this data, would be to give a special BoC interest rate specifically for financing certain housing loans and mortgages, and continue raising the rate for everything else. There might be pitfalls to that that I'm not considering, though. You'd want to be sure there's no way for other instruments to inappropriately get cheaper as a result.