From the IMF:
"A possible sign of “leakage” from tighter financial rules in Canada—which is a general problem that countries can face after tightening such rules—involves the expanding role of uninsured mortgages. These loans with loan-to-value ratio below 80 percent are not subject to the same regulatory tightening. These now comprise the bulk of mortgage originations and help fuel housing demand. For example, house price increases concentrated in single–family homes in fast-growing real estate markets seem tied to uninsured mortgages."