Walk any side street in Willowdale, Alderwood, Wexford or Applewood and you'll find the same house: a one-storey brick bungalow on a generous lot, built in the two decades after the Second World War. Those houses are now roughly 60 to 80 years old, and their owners all face the same decision: add a second storey, gut what's there, or knock it down and build new? For a bungalow renovation in Toronto or Mississauga, the right answer has less to do with taste than with the foundation, the zoning envelope and how much of the original house is worth keeping.
Quick answer: In 2026, a full gut of a typical GTA post-war bungalow, main floor plus a finished basement, commonly runs about $250,000 to $750,000 before HST, a second-storey addition usually lands around $300,000 to $550,000 all-in on its own, and a rebuild costs $350 to $650 per square foot to construct, so a 3,000 sq ft house is roughly $1.05 million to $1.95 million before land, design and soft costs. Add a storey when an engineer confirms the foundation can carry it and the zoning allows it. Rebuild when the foundation, basement height or layout would need so much work that you'd be paying new-build money for an old house.
Key takeaways
- The typical post-war bungalow we see has roughly 1,000 to 1,300 square feet on the main floor over a full basement, plaster walls, a centre bearing wall over a steel basement beam, and footings that were designed to carry one storey.
- A second storey starts with test pits. An engineer has to confirm that the existing footings and foundation walls can take the new load, or design the reinforcement, before anyone draws a floor plan.
- Expect the original systems to be near the end of their life: galvanized supply piping, a possible lead water service in houses built before the mid-1950s, an electrical service that is often 60 or 100 amps, and materials that may contain asbestos.
- Adding a storey and gutting the main floor together commonly reaches about $550,000 to $1.3 million, which is where a rebuild starts to compete on cost per usable square foot.
- Variances are common. Many bungalows already sit closer to a side lot line than current zoning allows, and in Toronto a 2026 variance application for an addition to an existing house costs $2,228.98.
- Plan the calendar honestly. Addition permits commonly take 8 to 14 weeks with 3 to 8 months of construction, while a custom home needs 2 to 6 months of design and permits and 5 to 14 months on site.
What's inside a 1945 to 1965 bungalow
These houses were built quickly and, for the most part, built well for their time. Seventy years on, most of them share the same features.
| System | What we usually find | What it means for your plans |
|---|---|---|
| Foundation | Poured concrete or concrete block walls on strip footings sized for a one-storey load; basements often well under 7 feet of clear height | A second storey needs engineering review; a livable basement often needs underpinning or benching |
| Framing | 2x4 exterior walls, ceiling joists sized only to carry a ceiling, rafters bearing on a centre wall | Ceiling joists can't become a floor without reinforcement or replacement; the centre wall is structural |
| Walls and ceilings | Plaster on gypsum or wood lath | Messy demolition; materials should be tested before they're disturbed |
| Plumbing | Galvanized steel supply lines, cast-iron stack, clay or cast-iron sewer lateral | Low water pressure and leaks; laterals cracked by tree roots; replacement is standard on a gut |
| Water service | Possibly lead in houses built before the mid-1950s | Replace the private side and coordinate with the municipality |
| Electrical | Often a 60 or 100 amp service, ungrounded circuits, few outlets | A service upgrade is almost always part of a gut or an addition |
| Heating | A furnace converted or replaced over the years, ducts sized for one floor | A second storey needs its own heating and cooling design |
| Insulation | Thin or missing in walls; sometimes vermiculite in the attic | Vermiculite should not be disturbed until it's tested |
On hazardous materials, Health Canada advises hiring a professional to test before renovating and lists plaster, floor tiles and pipe insulation among the older building materials that may contain asbestos, with a separate warning that vermiculite insulation may contain it. It recommends that vermiculite be left undisturbed and that you hire professionals trained to handle asbestos if you're renovating. We schedule testing before demolition so abatement, if needed, is priced and sequenced rather than discovered.
Many bungalows from the first post-war decade also predate the mid-1950s cut-off the City of Toronto uses for possible lead water services, so we check the pipe at the meter early and plan to replace the owner's portion in step with the City's side, as Toronto Public Health recommends. For lower levels, Toronto's Basement Flooding Protection Subsidy now offers up to $6,650 per property for eligible work completed on or after November 12, 2025, including up to $1,600 per backwater valve.
How the same house differs across the GTA
North York. Willowdale, Bayview Village, Bathurst Manor and Don Mills have many bungalows on deep lots, which is a large part of why second storeys and rebuilds are so common there. Lots that back onto the branches of the Don River can fall inside TRCA-regulated areas, and mature trees are everywhere. Permits run through Toronto Building and variances go to the North York panel of the Committee of Adjustment. Our home additions in North York are built around those constraints.
Etobicoke. Alderwood, Richview and Islington carry large stocks of post-war bungalows, with ravine edges along the Humber River, Mimico Creek and Etobicoke Creek. Variances go to the Etobicoke York panel. On narrower lots, side setbacks can push owners toward a partial second storey rather than a full one. We plan home additions in Etobicoke with the arborist and conservation review in the schedule from day one.
Scarborough. Wexford, Dorset Park and Cliffside have large stocks of brick bungalows, many on wide lots. Near the lake, TRCA's planning and permit work specifically addresses erosion along the Scarborough Bluffs. In Ward 23 (Scarborough North), zoning now permits fiveplexes and sixplexes in detached buildings, which changes the rebuild math on some lots; our Toronto multiplex guide explains those rules.
Mississauga. Applewood, Lakeview, Cooksville and parts of Port Credit and Clarkson have their own post-war bungalow stock, but the approvals sit with the City of Mississauga rather than Toronto. Mississauga requires permits for additions, dormers and roof alterations that raise height or change slope, and it lists average processing times of about 7 weeks for a residential alteration and 13 weeks for a new detached or semi-detached house. Depending on the watershed, Credit Valley Conservation, TRCA or, to a lesser extent, Conservation Halton may regulate creek and ravine lots, so check the mapping for your address. Our home additions in Mississauga follow that process.
Path 1: Add a second storey
A second storey roughly doubles your above-grade space while keeping the lot, the basement and, often, the street presence of the house. It's also the path most dependent on what's underground.
Foundation capacity comes first. Before design, we dig test pits beside the foundation so the engineer can measure footing width, depth and condition and look at the soil. Foundation walls are checked for cracking, bowing and water damage. The outcome is one of three answers: the existing footings can carry the new load; specific walls need underpinning or footing enlargement; or the new storey's loads are carried down to new footings on new posts and beams inside the basement. Each answer has a very different price, which is why we don't quote a second storey without it.
The roof comes off. Original ceiling joists were sized to hold up drywall or plaster, not people and furniture, so the new floor is usually a fresh joist system or substantial reinforcement. That means removing the roof, framing the floor and walls, and getting the new roof dried in as fast as possible. We schedule that window away from the wettest weeks and keep tarps and temporary roofing on site.
The stair decides the layout. A new stair takes floor area on both levels, typically where a hallway, closet or small bedroom used to be. Its location fixes the upstairs plan, so we resolve it early.
Mechanicals get redesigned. Ducts sized for one storey can't serve two. Most second-storey projects add a second heating and cooling system or replace the existing one with equipment designed for the whole house, and an electrical service upgrade is usually part of the scope.
Permits in Toronto. The Small Residential Additions permit requires a roof plan, elevations showing limiting distance and unprotected openings, sections with footing and foundation details, and an energy efficiency design summary under the Building Code's SB-12 standard. Additions also need a Tree Declaration Form and a Municipal Road Damage Deposit, and when the combined additions total 100 square metres or more, the site must post a Residential Infill Public Notice. As of January 1, 2026, the permit fee for new floor area in single-family dwellings, semis and townhouses is $18.56 per square metre, plus $56.33 for any new residential unit.
Cost and time. New space added through an addition typically runs $400 to $700 per square foot, and most second-storey additions land around $300,000 to $550,000 all-in. Large full-footprint second floors with premium finishes can go higher. Plan on 8 to 14 weeks for permits and 3 to 8 months of construction, with most families moving out while the roof is off. Our breakdown of second-storey addition costs in Toronto goes line by line.
Path 2: Gut the bungalow and keep the footprint
For owners who want single-level living, plan to age in place or simply like the scale of the house, a full gut is often the right call. Everything comes out to the studs: plaster, piping, wiring, ductwork, insulation, kitchen and bathrooms.
The structural move in almost every bungalow gut is the centre bearing wall. Replacing it with a flush beam, new posts and new footings opens the kitchen to the living and dining rooms, and our guide to removing a load-bearing wall in Toronto covers how that's engineered and inspected. The other big decision is the basement. If you want real living space downstairs, lowering the floor by underpinning adds roughly $70 to $150 per square foot, or about $35,000 to $85,000, and basement height is usually the largest single cost variable below grade.
A full gut typically works out to $200 to $450 per square foot. On a 1,000 to 1,300 square foot main floor that is roughly $200,000 to $585,000, and bringing the basement up to a finished level as well usually adds $50,000 to $160,000, so a whole-house bungalow gut commonly lands between about $250,000 and $750,000 before HST. Toronto's 2026 permit fees are $11.53 per square metre for interior alterations and $13.41 per square metre for residential alterations and renovations, and in our planning a typical gut runs five to eight months on site after design and permits. A gut can also be phase one: framing the new main floor to carry a future storey costs far less now than retrofitting later. That conversation belongs at the start of planning any full renovation in North York.
Path 3: Demolish and rebuild
A rebuild makes sense when the house is working against you: footings too small to carry a second storey without major underpinning, a basement too low to use without lowering every wall, a layout that would need nearly every wall moved, or a target of 3,000 square feet with taller ceilings and a full-height basement that the old structure can't deliver.
Construction for a ground-up custom home in Toronto typically runs $350 to $650 per square foot, so a 3,000 square foot house lands around $1.05 million to $1.95 million in construction, before land, design and soft costs. On a bungalow teardown, expect 2 to 6 months of design and approvals before the demolition crew arrives, then 5 to 14 months of construction.
In Toronto, the demolition permit for a house being replaced is applied for after the new house permit has been submitted, and the site needs a Residential Infill Public Notice, a Tree Declaration Form and a road damage deposit. The City also notes that owners demolishing a home or undertaking a major renovation may be eligible for a property tax rebate. A rebuild on land you already own is what Tarion calls a contract home, and contract homes carry the same statutory new home warranty structure as other new homes: one-year coverage for workmanship and materials, two-year coverage for items such as water penetration and Building Code health and safety violations, and seven-year coverage for major structural defects. Our ground-up custom homes are enrolled with Tarion. If you're weighing this path in North York, our custom homes in North York page covers the lot and zoning side.
Which path fits your house
| If this is true | Lean toward |
|---|---|
| Footings and foundation walls test sound, and zoning allows the height | Add a second storey |
| You want one-level living and the main floor size works | Gut and keep the footprint |
| You need both a second storey and a full gut, and the basement needs lowering | Price a rebuild alongside the renovation |
| The foundation is cracked, wet or undersized across most walls | Rebuild |
| The lot is in a sixplex area and you're open to rental units | Compare a rebuild as a multiplex |
| The budget is fixed and the house is sound but dated | Gut now, frame for a future storey |
Side-by-side costs and timelines
Costs and timelines below are typical planning ranges to confirm on site, not quotes.
| Path | Typical 2026 construction cost | Typical timeline after design | What you keep |
|---|---|---|---|
| Second-storey addition | $300,000 to $550,000 all-in | 8 to 14 weeks of permits, 3 to 8 months of construction | Foundation, basement, main-floor structure |
| Full gut, main floor plus basement | about $250,000 to $750,000 before HST | Permits, then 5 to 8 months of construction | Footprint, foundation, exterior walls |
| Second storey plus full gut | about $550,000 to $1.3 million | 8 to 12 months or more on site | Foundation and exterior walls |
| Demolish and rebuild, 3,000 sq ft | $1.05 million to $1.95 million | 2 to 6 months of design and permits, 5 to 14 months of construction | The lot |
The third row is the one that surprises people. Once an addition, a gut and underpinning are all on the table, the renovation can cost as much per usable square foot as new construction, while still leaving you with an old foundation and compromises in ceiling height. That's when we price both routes side by side before anyone commits.
Zoning and the Committee of Adjustment
Many bungalow lots can take a second storey within the existing zoning. Others need relief for height, side yard setbacks, building depth, lot coverage or floor space index, often because the original house already sits closer to a lot line than today's rules allow. Toronto strongly recommends a zoning review before applying, so every required variance is identified up front.
To approve a minor variance, Toronto's Committee of Adjustment must be satisfied that the general intent of the Official Plan and the Zoning By-law is maintained, that the proposal is appropriate for the development of the land, and that the variance is minor. Owners within 60 metres are mailed notice at least 10 days ahead of the hearing, and the property has to display a notice sign over the same period. Most appeals go to the Toronto Local Appeal Body, and since November 28, 2022, only the applicant, the Minister, specified persons and public bodies can appeal. Mississauga's Committee applies the same four tests, uses seven citizen members appointed by Council, and sends appeals to the Ontario Land Tribunal. If your second storey needs relief, our Committee of Adjustment guide sets out what the hearing involves and how many months to add to the schedule.
Trees and ravines
Mature trees are part of what makes these neighbourhoods, and they shape what you can build. On a bungalow lot, the trees to worry about are often the big silver maples and oaks planted when the house was new. In Toronto, any private tree with a trunk of 30 centimetres or more needs a permit to injure or remove, and some of those post-war plantings may now be large enough for the City's Distinctive Tree category, introduced September 1, 2026 for healthy trees over 61 centimetres, which City staff identify and the permit review must take into account. A drop in the private threshold to 20 centimetres has been endorsed but not yet implemented. A tree protection zone can rule out the rear addition you had in mind or change where new footings go, so we bring in an arborist before design. If the lot falls in a TRCA-regulated area, the conservation authority's permit comes before the building permit.
FAQ
Can my bungalow's foundation support a second storey?
Sometimes, and only an engineer can tell you after test pits expose the footings. Many post-war footings were sized for one storey, so the answer is often reinforcement of specific walls or new footings inside the basement rather than a simple yes or no.
Is it cheaper to add a second storey or rebuild?
A second storey on its own is usually cheaper, commonly $300,000 to $550,000 all-in. Combined with a full gut and underpinning, a renovation can reach $1 million or more, which puts it close to a rebuild of similar size.
Do I need a minor variance to add a second storey in Toronto?
Not always. It depends on your lot's height, setback, depth, coverage and density limits. Many bungalows were built closer to the side lot lines than current zoning allows, which is a common reason for a variance. A zoning review answers it before design is finished.
What hazardous materials should I expect in a 1950s bungalow?
Possibly asbestos in vermiculite insulation, plaster, pipe insulation or floor tiles, and possibly a lead water service if the house was built before the mid-1950s. Test before demolition and budget abatement as a planned line item.
Can we live in the house during a second-storey addition?
Most families move out for at least the roof-off and framing period, and often for the full project once the main floor and mechanicals are also being reworked. A gut renovation almost always means moving out.
Does a rebuild come with a warranty?
Yes. A new home built on land you already own is a contract home under Tarion, with one-year, two-year and seven-year coverage. Renovations and additions carry our own workmanship warranty instead.
Still torn between going up, gutting or starting over? We'll arrange the test pits, check the zoning and price each route side by side under a fixed-price contract. Read more about our home additions services, run the numbers through our free online estimate, or contact our team to arrange a foundation assessment.