The client
A dual-income professional couple self-building a home in Canmore, a mountain-town market where rock and soil conditions routinely complicate foundation work. Their construction mortgage was committed at $520,000, released in stages against the builder’s progress.
Borrowers
Dual-income couple, salaried
Combined income $17,500/month
Committed construction mortgage
$520,000
Staged draws against progress
The change order
Engineered footings for rock/soil conditions
Added $38,000 mid-build
As-complete appraisal (updated)
$700,000
Reflected the completed structural work
Property carrying costs
Property tax $380/mo; heat estimate $190/mo
Lender-standard figures
Other debt
One auto loan at $620/mo
Current
The problem
Cost overruns on a self-build are common enough to show up in the volume of housing starts that fluctuate with input costs and weather every season, but a committed construction mortgage is a fixed number until someone re-underwrites it. The change order here did not threaten whether the home could be finished — it threatened whether the final draw, sized against the original $520,000 commitment, would actually cover the last stage of work.
Left alone, the gap would have stalled the final draw entirely: the lender had no reason to release money against a budget it had never approved.
The numbers
A short-term top-up bridged the two months it took to get the lender’s commitment increased.
| The top-up, and the increased final draw | Amount |
|---|---|
| Change-order overrun | $38,000 |
| Monthly cost at 10.49% interest-only | $332 |
| Interest over the 2-month top-up | $664 |
| Original commitment + overrun = final construction mortgage | $558,000 |
$558,000 against the updated $700,000 as-complete appraisal is 79.7% loan-to-value — the appraisal increase, driven by the structural upgrade itself, is what created the room to fund the overrun without new cash from the borrowers.
Qualifying the completed construction-to-term mortgage
| Rate & payments | Figure |
|---|---|
| Contract rate (illustrative, not a quote) | 5.89% |
| Minimum qualifying rate — greater of contract + 2% and 5.25% | 7.89% |
| Monthly payment at the qualifying rate | $4,220 |
| Monthly payment at the contract rate | $3,534 |
| GDS / TDS | Monthly |
|---|---|
| Payment at the qualifying rate | $4,220 |
| Property tax | $380 |
| Heat | $190 |
| GDS: $4,790 ÷ $17,500 → 27.4% | ✓ |
| Auto loan | $620 |
| TDS: $5,410 ÷ $17,500 → 30.9% | ✓ |
The underwriting question here was never the couple’s ability to carry the debt — it is a rule that changes at 20% down that this uninsured file was measured against a lender-set benchmark rather than a CMHC ceiling, and the file cleared it with room to spare.
The solution
An RECA-licensed mortgage associate treated the change order as a re-underwriting problem to solve immediately, not a cost to absorb at the end.
Arranged a short-term top-up on the $38,000 shortfall so the trades already on site were not delayed waiting on the lender’s decision, then presented the updated as-complete appraisal — reflecting the engineered footings themselves — to support increasing the lender’s committed amount at the final draw.
Understanding how progress advances actually get released made the timing obvious: the appraisal had to be in the lender’s hands before the final draw request, not attached to it as an afterthought.
The outcome
Funded: the final draw released against the increased $558,000 commitment, the top-up repaid in full, and the file rolled into a construction-to-term mortgage at 79.7% LTV.
Alberta charges no provincial land transfer tax. Registration fees applied at the land-titles office instead, left qualitative here rather than quoted to the dollar, alongside the usual legal costs of converting a construction mortgage to a term mortgage.
What to take from this file
- 01Fix a financing gap the moment a change order is signed, not when the final draw request is due.
- 02An updated as-complete appraisal is often the fastest way to close a cost-overrun gap. Present it before assuming the lender’s original commitment is final.
- 03Short-term top-ups are a bridge, priced by the month — not a renegotiation of the whole file.
- 04Budget contingency into a self-build’s financing plan before it is needed. Rock and soil conditions in a market like Canmore make overruns more likely, not less.
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%.
- ▸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:
- ▸10.49% top-up rate / 5.89% construction-to-term contract rate — rates are lender-specific and move daily; not quotes.
- ▸draw-schedule percentages and the 2-month top-up window — each lender publishes its own draw schedule and timelines.
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.