The client
A family self-building a bungalow with a legal secondary suite in Calgary, built to the Alberta Building Code's own secondary-suite requirements from the start rather than converted after the fact. The construction-to-permanent mortgage was priced to include the suite's rental income at the insured take-out.
Property
New build with legal secondary suite, Calgary
Appraised value on completion
$680,000
Down payment (10%)
$68,000
Mortgage
$630,972 insured, 90% LTV
Projected suite rent
$1,850/month
The problem
The main house passed its Building final on schedule -- framing, insulation, occupancy inspection, all through the standard track. The suite's income didn't automatically come with it, because a secondary suite isn't just a smaller version of the same inspection.
What makes a secondary suite its own compliance item
- ▸A one-hour-class fire and smoke separation between the suite and the rest of the house, with any connecting door self-closing
- ▸A dedicated egress window in the suite's bedroom: an unobstructed opening of at least 0.35 m², with no single dimension under 380 mm, openable without keys or tools
- ▸These requirements are specific to a secondary suite and are inspected and certified on their own -- passing the main dwelling's occupancy inspection doesn't itself confirm the suite meets them
- ▸Until the suite-specific certificate was issued, the lender treated the suite as unrented space, not income-producing space, for the take-out
The gap wasn't a code failure -- the suite was built correctly the first time. It was a sequencing gap: the file's projected rental income relied on a certificate that hadn't been booked yet, on a different inspection track than the one the main house had already cleared.
The numbers
This is an insured mortgage, so 39% GDS / 44% TDS are CMHC's actual ceilings here, not illustrative lender policy.
| The build | Amount |
|---|---|
| Appraised value on completion | $680,000 |
| Down payment (10%) | $68,000 |
| Base mortgage before premium | $612,000 |
| CMHC premium (90% LTV, 3.10% band) | $18,972 |
| Insured mortgage | $630,972 |
With and without the suite's income
| Suite income counted? | Qualifying income | GDS | TDS |
|---|---|---|---|
| No (certificate not yet issued) | $12,800/mo | 39.8% | 41.7% |
| Yes (certificate issued, 50% add-back) | $13,725/mo | 37.1% | 38.8% |
Sizing
| Mortgage math | Figure |
|---|---|
| Minimum qualifying rate — greater of contract + 2% and 5.25% | 7.39% |
| Monthly payment at the qualifying rate | $4,572 |
| Monthly payment at the 5.39% contract rate | $3,811 |
Without the suite's income, GDS came in at 39.8% -- over CMHC's 39% ceiling on its own. The file wasn't broken; it was waiting on one certificate.
The solution
The mortgage associate booked the suite-specific compliance inspection as its own line item from the start of the build, rather than assuming it would be folded into the main house's occupancy inspection.
Building the suite to code from day one meant the certificate was a formality once booked -- the only real risk was timing it after the draw schedule needed the income counted, not the suite failing an inspection it was always going to pass.
The outcome
The suite's compliance certificate was issued nine days after the main house's occupancy inspection. With the suite's $1,850 monthly rent added back at 50%, qualifying income rose to $13,725/month, GDS fell to 37.1% and TDS to 38.8% -- both back inside CMHC's insured ceilings before the final advance was requested.
50% add-back is this lender's own policy for this file; other lenders treat secondary-suite rental income differently.
What to take from this file
- 01A secondary suite's code compliance is certified separately from the main dwelling's occupancy inspection. Passing one doesn't confirm the other -- book both, and don't assume either covers the second.
- 02Egress and fire-separation specifics are concrete enough to design for from day one. A 0.35 m² window with no dimension under 380 mm, and a self-closing separation door, cost nothing extra to get right in the framing stage -- and everything to retrofit after.
- 03On an insured file, don't count rental income the lender hasn't yet certified as fundable. A ratio that only works with unconfirmed income isn't approved -- it's provisional.
- 04Book the less-standard inspection first, not last. A suite-specific compliance inspection is easy to forget to schedule separately until the take-out date is already close.
Sources
Every regulatory figure in this file traces to one of these primary sources. Client details and anything that varies by lender are illustrative, as flagged below.
- ▸OSFI — Minimum qualifying rate for uninsured mortgages — the minimum qualifying rate — greater of contract rate + 2% or 5.25%.
- ▸CMHC — Purchase (Mortgage Loan Insurance) — default-insurance premium schedule by LTV band (25-year amortization).
- ▸CMHC — CMHC Reviews Underwriting Criteria — GDS 39% / TDS 44% maximums and the 600 credit-score floor for insured files.
- ▸Provincial/territorial mortgage-broker legislation fetched directly (bclaws.gov.bc.ca, legisquebec.gouv.qc.ca, fcaa.gov.sk.ca, web2.gov.mb.ca, nslegislature.ca, assembly.nl.ca) plus FCNB's own site for NB and CanLII's index for PE — see notes for per-province method — provincial mortgage regulators and licence titles.
Illustrative in this file — lender-specific, not rules:
- ▸5.39% contract rate — rates move daily; not a quote.
- ▸$350 property tax / $170 heat / $240 other debt — illustrative carrying costs for this file.
- ▸$1,850 suite rent, 50% add-back — an illustrative deal figure and one lender's own rental-income policy, not a published rate or standard.
Authority & provenance
How this case file was built
We publish the origin, the verification method and the reviewer for every case file, so you can judge how far to trust it before you rely on it with a client.
Where it comes from
Derived from files handled by Treadstone’s fulfillment desk and from scenarios contributed by partner brokerages. Names, employers, exact amounts and dates are changed so no client or file is identifiable.
Provenance: Composite — a pattern seen repeatedly on fulfilled files, not a single transaction.
What is verified
Every regulatory figure traces to a primary source listed above and was checked against it on the date shown. The arithmetic is recomputed by machine on every rebuild.
Anything that varies by lender is labelled illustrative rather than stated as a rule.
Who reviewed it
Reviewed for Canadian regulatory accuracy before publication, and re-checked whenever a cited rule changes.
Reviewed by: Nicholas Parson, Treadstone Associates — reviews every case file before publication.
This case file is professional reference material for licensed mortgage professionals. It is not advice to a borrower, and it is not a lender commitment. Insurer rules, qualifying rates and provincial taxes change — confirm the current position with the insurer, regulator or lender before you rely on any figure here in a live file.