Is your lot a good candidate?
Most lots that hold an older house can take a new one, but the rules decide how big, how tall and how many units. Before you pay for drawings, check:
- Width and depth. Side yards come off the width, so on lots under about 40 ft a new home gets narrow and deep. Deep lots often run into a building depth or rear yard limit instead.
- The zone’s limits. In Mississauga, many older neighbourhoods cap house size and height. In south Oakville, the Residential Low zones limit floor area and height, with new rules for South Oakville neighbourhoods passed in June 2026 (By-law 2026-088).
- Trees, ravines and creeks. Protected trees and conservation authority areas (Credit Valley Conservation, Conservation Halton, TRCA) can move the house or add permits.
- Heritage. Designated properties and Heritage Conservation Districts, such as Old Port Credit Village in Mississauga or Old Oakville, need heritage approval before demolition.
Shortcut: a free Lot Check answers these for your address in two business days.
The steps, in order.
- Lot Check and site visit. Zoning, what fits, a budget range and a timeline.
- Survey and reports. A topographic survey, and an arborist report where trees are protected.
- Design and pricing. Concept plans and 3D views, then a line-by-line proposal.
- Permits. The building permit and the demolition permit, plus a minor variance at the Committee of Adjustment if the design needs one.
- Disconnections and a designated substances survey. Gas, hydro and water are cut off, and the old house is checked for asbestos and other hazards before it comes down.
- Demolition. Usually two to four weeks, including recycling and site grading.
- Construction. Under 12 months from building permit to keys at Oaksmith.
- Handover. A full walkthrough, warranty paperwork and your keys.
How long it takes.
| Stage | Typical time |
|---|---|
| Lot Check, survey and reports | 2 to 6 weeks |
| Design and pricing | 2 to 4 months |
| Building and demolition permits | 1 to 3 months |
| Committee of Adjustment, if needed | Add 3 to 6 months |
| Disconnections and demolition | 3 to 6 weeks |
| Construction | Under 12 months |
| Start of design to keys | About 15 to 20 months |
The biggest swing is approvals. A design that fits the zoning goes straight to a building permit; one that needs a minor variance waits for a hearing and the 20-day appeal period that follows.
What it costs.
Typical all-in budgets from Oaksmith’s 2026 cost model for a two-storey home with a finished basement, including design, permits, contingency, demolition and new service connections, before land and HST:
| Home size, above grade | Construction | All-in budget |
|---|---|---|
| 2,500 sq ft | $825K–$1.25M | $1.14M–$1.84M |
| 3,200 sq ft | $1.06M–$1.6M | $1.45M–$2.32M |
| 4,500 sq ft | $1.49M–$2.25M | $2.02M–$3.23M |
Construction is priced from $330 per square foot above grade with mid-level finishes, up to about $500 with premium finishes and a more complex design. The finished basement is priced at 35% of that rate. See what a custom home costs in the GTA for the full breakdown.
Mississauga specifics.
- Up to four units per lot as-of-right since late 2023, in buildings generally up to three storeys, so a basement or garden suite is easy to plan in.
- Many lots near the Credit River and its creeks need a Credit Valley Conservation permit; the east end falls under TRCA.
- Most replacement homes no longer need site plan approval, except within 120 m of the lakeshore or 300 m of a rail line.
- Wide lots may be worth splitting. See severing a lot in Mississauga.
Oakville specifics.
- Three units per lot (the provincial baseline); council declined a town-wide four-unit change in 2024.
- Floor area and height limits in the Residential Low zones shape most south Oakville designs, and many rebuilds ask for small variances. Designing to the 2026 rules from the start saves months.
- Conservation Halton regulates the creek valleys and the lakeshore, and larger private trees need a town permit.
- Four Heritage Conservation Districts: Old Oakville, First and Second Street, Trafalgar Road and Downtown.
How to keep it on schedule.
- Order the survey and arborist report first; everything else depends on them.
- Design to the zoning unless a variance is clearly worth three to six months.
- Request utility disconnections early; they can take weeks.
- Make your selections before construction starts, and order long-lead items such as windows early.
- Rent with a buffer of a month or two.
General information, current to November 4, 2026. Rules and programs change; check the details for your property before you rely on them.