What CMHC's Rental Market Survey Actually Measures — And Its Limitations
CMHC's RMS is the most widely cited source of Canadian rental data. But it has significant blind spots that investors need to understand before acting on its numbers.
Every serious multifamily investor in Canada has cited CMHC's Rental Market Survey at some point. It is the most comprehensive public source of vacancy and rent data for Canadian cities. It is also frequently misunderstood and misapplied.
Here is what it actually measures, and what it misses.
What the RMS Covers
The Rental Market Survey is conducted annually in October and covers purpose-built rental apartments in urban centres above certain population thresholds. It surveys buildings with three or more units that were purpose-built for rental — meaning units that have always been rental, not condos being rented by their owners.
This is the first and most important caveat: the RMS does not capture condos rented by investors, basement apartments, or secondary suites. In many Canadian cities, this secondary rental market is substantial and behaves differently from the purpose-built sector. In Toronto, for example, over 200,000 condominium units are on the rental market — a secondary supply pool that competes directly with purpose-built landlords but does not appear in the primary RMS vacancy numbers.
The October Snapshot Problem
Because the RMS is conducted in October, it captures a specific moment in time. Rental markets move throughout the year, with vacancy typically rising in winter and tightening after the September lease-up period. An October snapshot reflects seasonal conditions that may not represent annual averages.
For markets with large student populations, October data is captured after the fall lease-up — when vacancy is typically at its seasonal low. This can make markets appear tighter than they are on an annual average basis.
Geographic Limitations
The RMS covers census metropolitan areas and census agglomerations above defined thresholds. Many of Ontario's secondary markets — Chatham-Kent, Ingersoll, portions of Elgin County — fall outside these boundaries and are not covered by the standard survey.
CMHC does publish data for smaller centres, but with less frequency and less granularity than for major cities. Investors in these markets need to supplement CMHC data with local sources.
Rent Data Nuances
The RMS reports average rents for occupied units — not asking rents for vacant units. In a softening market, asking rents for newly vacant units may be declining while average occupied rents are still rising, because long-term tenants are paying below-market in-place rents.
This creates a situation where average rent growth looks positive in the CMHC data while actual market conditions for new leases are softer. Both things can be true simultaneously.
How to Use the RMS Properly
Despite its limitations, the RMS is valuable for identifying directional trends — is a market tightening or loosening? — and for making relative comparisons between markets at a point in time.
The key is to treat it as one input among several, not as the definitive read on market conditions. Supplement with asking rent data from rental listing platforms, local broker intelligence, and transaction comparables before making investment decisions. Cap rate data from brokerages like Colliers and CBRE provides an independent cross-check on how sophisticated market participants are pricing risk in a given geography.