Not a single payback number — a full sensitivity model. Conservative, base-case, and optimistic scenarios, plus what actually moves the needle on your return.
BOOK YOUR FREE ASSESSMENTMost payback estimates use one rent number and one cost number. Real returns depend on vacancy, tax reassessment, insurance uplift, and maintenance reserves too — and those variables move the number more than most homeowners expect. This model builds those in. For construction costs and city-by-city rent, see our Cost Guide and Payback Period by City.
Net monthly contribution below accounts for 8% vacancy, property tax increase, insurance uplift, and a 5% maintenance reserve — not just gross rent minus mortgage.
| Variable | Conservative | Base Case | Optimistic |
|---|---|---|---|
| All-in legalization cost | $135,000 | $105,000 | $72,000 |
| Monthly rent achieved | $1,900 | $2,100 | $2,300 |
| Vacancy (8%) | ($152) | ($168) | ($184) |
| Property tax increase/mo | ($180) | ($150) | ($120) |
| Insurance uplift/mo | ($60) | ($50) | ($40) |
| Maintenance reserve (5%) | ($95) | ($105) | ($115) |
| Net monthly contribution | $1,413 | $1,627 | $1,841 |
| Payback period | 95 mo / 7.9 yr | 65 mo / 5.4 yr | 39 mo / 3.3 yr |
| Variable | Conservative | Base Case | Optimistic |
|---|---|---|---|
| All-in legalization cost | $85,000 | $62,000 | $42,000 |
| Monthly rent achieved | $1,450 | $1,650 | $1,850 |
| Vacancy (8%) | ($116) | ($132) | ($148) |
| Property tax increase/mo | ($110) | ($90) | ($70) |
| Insurance uplift/mo | ($45) | ($40) | ($35) |
| Maintenance reserve (5%) | ($73) | ($83) | ($93) |
| Net monthly contribution | $1,106 | $1,305 | $1,504 |
| Payback period | 77 mo / 6.4 yr | 48 mo / 4.0 yr | 28 mo / 2.3 yr |
Niagara's base-case payback of 4.0 years compares favourably to the GTA base-case of 5.4 years — for investors targeting a sub-5-year payback, Niagara offers a structurally shorter path to it.
Not every variable in the model above is equally important — and not every one is something you can actually control.
| Variable | Impact on Payback | Investor Control |
|---|---|---|
| All-in renovation cost | ±30–45% | High |
| Achieved monthly rent | ±20–30% | Medium |
| Permit timeline & carry costs | ±10–20% | Low |
| Vacancy rate | ±5–8% | Medium |
| Property tax reassessment | ±5–10% | None |
Renovation cost is the single highest-leverage variable investors can control. Right-sizing scope — and avoiding unnecessary structural work — has a bigger impact on payback than almost any rental rate improvement. See what drives that cost in our Cost Guide's price-variable breakdown.
Rental income is only one dimension of ROI. A legally registered second suite adds measurable resale value — often covering a meaningful share of legalization cost on exit, independent of rent collected along the way.
| Property & Area | Est. Value Without Suite | Premium Range | Dollar Value Added |
|---|---|---|---|
| Detached, Mississauga | $1,100,000 | +10–14% | $110K–$154K |
| Detached, St. Catharines | $620,000 | +10–15% | $62K–$93K |
| Detached, Niagara Falls | $590,000 | +8–14% | $47K–$83K |
Regional estimates as of Q1 2026. Individual results vary by property condition, location, and market conditions at time of sale.
Since renovation cost is the variable with the most leverage over your payback period, it's also the one PARAHOMES controls most tightly — a fixed price agreed before construction starts, with a 100% first-submission permit approval rate to avoid the carrying-cost drag of a rejected application.
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