Know what is behind the number.

What the construction allowance includes

The per-square-foot rates cover standard new-build work: excavation and foundations; structural framing; roofing, cladding, windows, insulation and waterproofing; heating and ventilation; plumbing and electrical; required life-safety systems; fire and acoustic separation; stairs, kitchens, bathrooms and interior finishes. Normal trade labour, site supervision, temporary protection and waste removal are included.

Demolition and site services are separate: building or garage removal, external water/sewer/hydro connections, ordinary trenching, grading and basic site reinstatement. Major off-site infrastructure, contaminated soil, extraordinary shoring and rock excavation require a project-specific allowance.

Design and consultants are separate: architectural design, structural and building-services coordination, energy/code review and permit documentation. The 15% reserve is not a fee proposal. Survey, geotechnical testing, arborist investigations, administrative and close-out costs use the separate other-costs reserve.

Rates and durations are house planning assumptions, not published contractor prices or a promised schedule. Gross area includes basements being built. The model does not confirm site fit, planning permission or title.

What the sliders change

Area: gross constructed floor area across all floors, including a basement. This is not the building footprint or the usable area inside the homes. The combined project keeps main-building and rear-suite area separate.

Homes: the base multiplex rate assumes four main-building homes. Each additional home adds an illustrative $18,000 construction allowance for kitchens, services and separations; each fewer home removes the same allowance. This adjustment is applied before the finish factor, followed by normal fees, contingency and tax calculations. A rear suite is always one additional home. Changing home count holds floor area constant and does not establish that the new layout is feasible.

Finish & specification: Essential applies 0.92×, Considered 1.00× and Elevated 1.18× to construction, including the home-count adjustment. Considered retains the original construction rates. These are sensitivity assumptions for comparison, not measured contractor-price differences. Rents do not increase automatically with finishes.

Access & servicing: the existing servicing reserve remains. Constrained adds 3% and Complex adds 7% of construction before finish adjustments to site costs; Typical adds nothing. These allowances illustrate cost sensitivity. They do not price major shoring, remediation, rock or off-site infrastructure.

Area preview: equal-sized homes with an illustrative 18% of main-building area allowed for walls, stairs and services, or 10% for a standalone rear suite. The combined rear suite also uses 10%. The diagram is not a designed layout, a floor plan, code compliance, or a verified usable-area takeoff. The 400 sq ft advisory is a design discussion prompt, not a zoning or Building Code minimum.

Try a change: each comparison changes only the named input and recalculates the full works budget. Differences are rounded to the nearest $1,000. Fixed costs and unit-based charges can create steps rather than a smooth increase. A pinned estimate is kept only in the open page and reset clears it.

Reserves and other project costs

Design = 15% of construction. Contingency defaults to 20% of construction plus demolition/site services, including the selected site adjustment; the slider allows 10–30%. A lower reserve changes the budget, not the underlying risk. Other costs = the greater of 3% of multiplex construction or $20,000, and the greater of 4% of rear-suite construction or $15,000. Combined projects include both other-cost allowances.

Rental setup reserves $3,000 per unit for leasing and operating setup. Condominium approval, legal, survey/registration and warranty work reserves $35,000 plus $10,000 per multiplex unit. These are allowances, not fee schedules. The rear suite is not assumed to have an independent saleable title. Personal use of one rear suite adds no ownership-setup reserve.

Permits and development charges

Permits use $18.56 per m², a $214.79 minimum and $56.33 per new unit. Square feet convert at 0.09290304 m² each. Multiplex projects add a $214.79 demolition permit and $1,030.99 environmental-review reserve. Related application and trade-permit reserves are $5,000 for a multiplex, $3,000 for a rear suite and $8,000 combined.

A 2–6-unit new development reserves one municipal charge under the units-2–6 exemption assumption. The model uses the two-bedroom “multiples” category: $68,199 for a qualifying 4+ unit rental building, otherwise $113,938. At seven total units, the combined model conservatively reserves charges on all seven, pending a City assessment. A standalone rear suite assumes one existing main house and the additional-unit exemption.

No redevelopment credit is assumed. The conditional 2026 reduction program appears separately. Education charges reserve $3,893 per new unit before separate exemptions. These are current-dollar figures: education rates rise to $4,193 on December 3, 2026. Dates in the financing scenario do not forecast or lock municipal fees.

Your equity, borrowing and timing

Existing secured debt = current home value minus owned equity. Include every mortgage and HELOC balance in that equity figure. Indicative borrowing room = the greater of zero or 80% of home value minus existing secured debt. This is a reference ceiling before redevelopment, not an approved amount; HELOC-specific limits differ. Appraisal, income, lender consent to demolition and construction terms still matter.

The default project loan covers 75% of the pre-financing works budget, including the construction HST reserve. You can change this share. This is a financing scenario; it is not a loan-to-value assessment. Land equity is not deducted from construction costs, and equity borrowing is never added on top of the same project loan.

Design begins six months before the selected construction start. Predevelopment costs comprise design, half the other-cost reserve, HST on those items and permits. Choose when to borrow:

• During design: an early draw is limited to available equity room, predevelopment costs and the project loan. It earns six months of interest before construction and remains outstanding during the build. The remaining project loan uses a 50% average construction draw.
• At construction start: predevelopment needs bridge capital. The project loan uses a 50% average draw over the modeled construction period.
• At completion: the project is self-funded until completion. No construction-loan interest is charged; the model shows the full capital needed before a possible refinance.

Construction interest defaults to 8% annually. Fees reserve 2% of the project loan. Site carrying adds 1% annually on construction plus demolition/site work. These allowances are cash-funded in the model; they are not added to loan principal. Capital beyond the loan = total works budget minus the project loan. Existing mortgage payments before completion, refinance penalties and relocation costs remain separate.

Completed debt = existing secured debt plus project borrowing. No reduction for interim mortgage principal payments or tax recoveries is assumed. An actual completion refinance depends on completed value, income, debt coverage and lender terms. CMHC programs may offer different structures; no insured loan entitlement is assumed here.

After-completion monthly costs

PBR / rental hold: completed debt is amortized at your chosen rate and period. The example uses 5.5% and 25 years. The fixed-rate formula uses monthly rate i = (1 + annual rate ÷ 2)^1/6 − 1, with the annual rate expressed as a decimal. Payment = principal × i ÷ [1 − (1 + i)^{−12 × years}]. At zero interest, payment is principal divided by the number of months. These are example terms, not current offers.

Rent defaults are examples: $2,800 per multiplex unit and $2,600 per rear suite. You can enter other rent from the same property. The calculation deducts 5% vacancy, 5% maintenance, 8% management and a separate 5% capital replacement reserve. Vacancy reduces income; it is not charged again as an operating cost.

Monthly insurance = (hard construction × 0.3% + current home value × 0.15%) ÷ 12. Utilities = $125 per new unit, plus $100 for common services or $125 for an existing main house in a standalone ADU scenario. These are planning reserves, not quotes or utility-rate forecasts.

Automatic annual property tax applies Toronto’s 2026 residential/new-multi-residential rate of 0.767311% to current home value plus hard construction costs. This is a conservative reserve proxy, not an MPAC assessment or a completed-property valuation. Enter an actual annual estimate to override it. No special property-tax subclass reduction is assumed.

Net operating income (NOI) = rent after vacancy minus property tax, insurance, utilities, maintenance and management. Debt coverage = NOI ÷ mortgage payment. Cash flow then deducts the full mortgage payment and capital reserve. No income tax, appreciation or capital gains are modeled. The rate stress test adds one percentage point to the mortgage rate.

Condo / sell: completed debt stays outstanding at the construction interest rate until sales close. Monthly carry includes that interest, property tax, insurance, utilities and maintenance of 0.3% of hard construction annually. No rent is assumed. The selected holding period multiplies the monthly cost; phased closings and principal paydown are not modeled. After sales, individual owners’ mortgages and condo fees are separate.

Monthly totals include the existing property debt and new project borrowing. For an ADU, they therefore cover the whole property’s debt, while rental income starts with the new suite. Add main-house rent if applicable. Future condominium sales, selling commissions and sale-tax settlements need a separate exit model.

Construction HST and housing rebates

The works budget reserves 13% on modeled taxable construction, site, design, contingency, other-cost and ownership allowances. Government fees, development charges and financing reserves are excluded from that tax base. Potential construction input credits remain separate until registered-builder eligibility is confirmed.

The PBR path checks at least four units in the main rental building and the selected construction dates against the start-before-2031 and completion-before-2036 windows. It assumes qualifying long-term use, but does not establish eligibility. A separate laneway suite does not automatically inherit the main building’s relief. Personal-use and ordinary rental rebates need the relevant claimant and value information.

Housing rebates concern tax on the relevant property transaction or self-supply; they are not another subtraction from construction input tax. No temporary enhanced rebate, sale tax or self-supply fair-market-value amount is invented by the model.

Property value comparison

Use the current home value in the equity tab and optionally enter your estimated completed value of the whole property, including land. For a rear suite, both values include the existing house and site. For condominium sales, the completed value is the combined value of all units before selling costs. Support these assumptions with comparable sales or an appraisal for the proposed scope.

Value change = completed value − current value. Percentage change = value change ÷ current value × 100. Increase less works budget = value change − the displayed project works budget. The last figure excludes selling costs, additional sale or self-supply tax and possible tax recoveries; it is not a profit or return-on-investment calculation.

Values are entered by you, not estimated from construction spending. Completed-value entries are kept separately for rental and condominium or personal-use scenarios. Review them whenever the floor area, unit count or scope changes. Empty or invalid entries show no value result; a decrease in value remains negative.

Read the totals in context

Works budgets exclude land acquisition, existing mortgage payments before completion, unusual remediation, major planning appeals, exceptional infrastructure and final sale/self-supply tax. Monthly costs start after completion and are not counted again in the works budget.

Project headlines round up to $1,000; other figures round to the nearest dollar. Inputs stay in the browser’s memory and reset on reload. The model is a starting conversation, not a tender, appraisal, mortgage approval or tax filing.