# Construction Mortgages and the Draw Schedule — How Self-Builds Get Funded in Canada

> How Canadian construction mortgages work: progress draw mechanics, inspector sign-offs, interest-only carry costs, CMHC coverage, and the documentation lenders require at each stage.

Category: Purchase
Last verified: 2026-04-20
Source: https://ratellow.com/scenarios/construction-mortgage-draw-schedule-canada

## Who this is for
Salaried borrowers financing a custom-build or spec-build on owned or purchased land — typically with a fixed-price contract and a builder, or acting as their own general contractor on a self-build.

## Summary
A construction mortgage releases funds in staged advances — typically three to five draws — tied to verified completion milestones rather than disbursing the full loan at closing. Between draws, borrowers pay interest only on the cumulative amount advanced, which keeps carry costs manageable but requires disciplined cash-flow planning. CMHC insures construction mortgages under its Progress Advance program, and the insured route is available with as little as 5% down on the completed-value appraisal — a meaningful lever for borrowers who own the land outright or have equity in it.

## Worked example
A salaried household in Ontario contracts a builder for a $900,000 custom home on land they already own (appraised at $150,000). The lender approves a construction mortgage based on a completed-value appraisal of $1,050,000. With 5% down on the $900,000 build cost ($45,000), the insured mortgage is $855,000 plus the CMHC premium of $34,200 (4.00% tier), for a total insured amount of $889,200. Funds are released across four draws as construction milestones are certified.

- Completed-value appraisal: $1,050,000
- Construction mortgage (insured): $889,200 (incl. CMHC premium)
- Interest-only carry at 5.25% on Draw 1 ($222,300): ~$972/month
- Interest-only carry at 5.25% on full advance ($889,200): ~$3,888/month
- CMHC premium (4.00% tier, 90–95% LTV): $34,200

## Framework
### How the draw structure works
Construction mortgages disburse in tranches — most lenders use three to five draws, though CMHC's Progress Advance program formally supports up to six. Each draw is triggered by a construction milestone: typically (1) foundation complete, (2) framing and roof sheathed, (3) mechanical rough-in (plumbing, HVAC, electrical), (4) drywall and interior finishes, and (5) substantial completion. Before each advance, the lender orders an inspection — either through CMHC's network or an approved independent inspector — who certifies the percentage of work complete. The lender advances funds up to the certified percentage of the total approved loan. **No draw is released without an inspection certificate.** The borrower pays interest only on the cumulative drawn balance between advances; full amortizing payments begin after the final draw and the mortgage converts to a standard term.

### CMHC Progress Advance Mortgage — insured route mechanics
CMHC insures construction mortgages under its Progress Advance program, which mirrors standard insured underwriting with one key difference: the loan-to-value is calculated against the **as-completed appraised value**, not the land value or cost-to-date. This allows borrowers with land equity to treat that equity as part of their down payment. Minimum 5% down applies on the first $500,000 of completed value and 10% on the portion between $500,000 and $1,500,000 (the December 2024 cap increase). Premium tiers are identical to standard insured: 4.00% at 90–95% LTV, 3.10% at 85–90%, 2.80% at 80–85%. Sagen and Canada Guaranty offer equivalent programs. The insured route caps the mortgage at $1,500,000 completed value; above that, conventional construction financing applies with a minimum 20% down.

### Conventional (uninsured) construction financing
For builds where the completed value exceeds $1,500,000, or where the borrower prefers to avoid the insurance premium, conventional construction mortgages require a minimum 20% equity position based on the as-completed appraisal. Most Schedule A banks and credit unions offer this product; monoline lenders are less common in the construction space because of the operational complexity of draw management. Rate pricing on conventional construction mortgages typically runs **25–50 bps above** the equivalent term on a standard purchase mortgage, reflecting the lender's construction-period risk. Some lenders charge a construction administration fee of $500–$1,500 to cover inspection coordination. The rate is usually locked for the construction period (6–18 months) and then converts to a standard term at the prevailing rate at conversion — rate-lock-at-conversion provisions vary significantly by lender and should be negotiated explicitly.

### Cash-flow mechanics during the build
The interest-only carry period is the most underestimated cost in construction financing. As each draw is advanced, the interest obligation steps up. On a $889,200 mortgage at 5.25%, the monthly interest on the full advance is approximately $3,888 — but the borrower is also typically paying rent or carrying an existing property during construction. **Model the worst-case carry scenario**: assume the build runs 20% over schedule (common) and calculate the total interest cost at full advance for that extended period. A 6-month build that extends to 9 months adds roughly $11,664 in carry interest at the above example rate. Most lenders allow the construction period to run 12–18 months before requiring conversion; extensions beyond that require lender approval and sometimes a fee.

### Documentation and qualification standards
Qualification follows OSFI B-20 stress-test rules: the qualifying rate is the greater of the contract rate plus 200 bps or 5.25% (the current floor as of 2026). GDS and TDS ratios are calculated on the **fully amortized payment** at the converted term, not the interest-only carry payment — this is the correct approach and means qualification is based on the permanent debt service. Required documentation beyond standard income verification includes: **fixed-price construction contract** (open-cost contracts are harder to insure), **builder credentials** (provincial licensing, GST/HST registration, Tarion or equivalent new-home warranty enrollment in applicable provinces), **as-completed appraisal** from a lender-approved appraiser, **building permit**, and **site plans or architectural drawings**. Owner-builder files (no licensed GC) face additional scrutiny — most insured lenders require the borrower to demonstrate construction management experience or hire a project manager.

### Rate lock and conversion strategy
The construction period rate and the converted permanent mortgage rate are two separate decisions. Some lenders offer a **rate hold at application** that locks the permanent rate for the full construction period — typically at a 10–20 bps premium over the standard rate hold. Given the 2025–2026 rate environment (5-year fixed roughly 5.00–5.50%), locking the permanent rate at application provides certainty but costs a small premium. The alternative — floating to conversion and taking the market rate — is a reasonable bet if the BoC overnight rate (currently ~2.75%) continues its easing trajectory, but introduces rate risk over a 12–18 month build window. **Borrowers who cannot absorb a 75–100 bps adverse rate move should lock at application.** Confirm whether the lender's rate hold survives a draw extension request — some lenders reset the rate hold clock on extensions.

## Key considerations
- Land equity counts toward your down payment in the as-completed LTV calculation, but only if the land is owned free-and-clear or the existing land mortgage is being discharged at construction close. A land mortgage that remains in place is treated as a lien and complicates the construction advance structure.
- GST/HST applies to new construction and is not included in most builder contracts as a line item — confirm whether your fixed-price contract is GST/HST-inclusive or exclusive. On a $900,000 build in Ontario, HST at 13% adds $117,000 if not already embedded, though the New Housing Rebate partially offsets this for owner-occupied builds.
- Tarion warranty enrollment (Ontario) or equivalent provincial new-home warranty is a hard requirement for CMHC-insured construction mortgages on builder-contracted homes. Verify enrollment before submitting the mortgage application — late enrollment can delay draws.
- Cost overruns are not automatically covered by the construction mortgage. If the build exceeds the approved budget, the borrower must fund the overage from personal resources or negotiate a mortgage increase — which requires a new appraisal and lender approval. A 10–15% contingency reserve held outside the mortgage is standard practice.
- The construction mortgage converts to a standard term at substantial completion, not at occupancy permit issuance. Confirm the lender's definition of substantial completion — some require a final inspection certificate, others accept a statutory declaration from the builder.

## Common mistakes
- Underestimating the carry cost by modeling interest only on the first draw rather than the fully advanced balance — the difference can be $2,000–$3,000/month on a mid-size build, which creates cash-flow strain if the borrower is also paying rent.
- Using an open-cost or cost-plus construction contract instead of a fixed-price contract — most insured lenders will not advance on open-cost contracts because the completed value cannot be reliably established, forcing the borrower into conventional financing at 20% down.
- Failing to confirm the builder's Tarion (or provincial equivalent) enrollment before application — discovering this gap after approval delays the first draw and can push the build start by 4–8 weeks.
- Assuming the rate hold on the permanent mortgage survives a construction extension without confirming this in writing — some lenders expire the rate hold at the original completion date, exposing the borrower to market rates at conversion.
- Not budgeting for the GST/HST new housing rebate application timeline — the rebate is applied for after occupancy and can take 4–6 months to process; borrowers who count on it for post-build liquidity may face a gap.
- Treating the as-completed appraisal as a ceiling rather than a floor — if market conditions soften during the build and the completed value appraises below the original estimate, the LTV rises and the lender may require additional equity before releasing the final draw.

## Action steps
1. Commission an as-completed appraisal from a lender-approved appraiser before signing the construction contract — this establishes your LTV, confirms insurability, and gives you a realistic budget ceiling.
2. Obtain a fixed-price construction contract with a licensed builder who holds provincial new-home warranty enrollment; collect the warranty certificate number before submitting your mortgage application.
3. Model the full interest-only carry cost at the maximum advance amount for a build period 20% longer than the contractor's estimate — this is your stress-test for cash-flow, not the lender's.
4. Confirm in writing whether the lender's rate hold on the permanent mortgage survives a draw extension, and negotiate a rate-lock-at-conversion clause if the standard product does not include one.
5. Set aside a 10–15% cost contingency in liquid savings outside the mortgage — lenders will not advance beyond the approved amount, and overruns are the borrower's responsibility.
6. If the build is owner-occupied and under $1,500,000 completed value, run the CMHC Progress Advance route first — the insurance premium is almost always cheaper than the rate premium and larger down payment required on conventional construction financing.

## Sources
- Mortgage Loan Insurance — Homeownership Products — https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/mortgage-loan-insurance-homeownership-programs
- Guideline B-20 — Residential Mortgage Underwriting Practices and Procedures — https://www.osfi-bsif.gc.ca/en/guidance/guidance-library/final-revised-guideline-b-20-residential-mortgage-underwriting-practices-procedures
- GST/HST New Housing Rebate — https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/charge-collect-which-rate/real-property/new-housing-rebates.html
- Mortgages — Financial Consumer Agency of Canada — https://www.fcac-acfc.gc.ca/Eng/financial-literacy/life-events/buying-home/Pages/mortgages.aspx