What Design Build Costs in Scarborough in 2026

A 1,400-square-foot bungalow addition and main-floor renovation in Agincourt cost $485,000 last month, or $346 per square foot. A Highland Creek rebuild with a legal basement suite came in at $412 per square foot, including the TRCA permit and a variance for the rear setback. A Guildwood kitchen and bathroom gut, no structural work, ran $285 per square foot. Design build in Scarborough in 2026 runs $275 to $425 per square foot for most projects, with the number landing closer to $300 for renovations inside the existing envelope and $375 to $425 for additions or rebuilds that need permits, variances or conservation clearance.

The per-square-foot range is wide because Scarborough projects vary more than central Toronto ones. A Cliffcrest bungalow on flat land with no variances needed is a different animal from a Bluffs property inside the TRCA hazard setback, and the second one costs more per square foot even when the finishes are identical. The cost drivers are site conditions, permit complexity, the age and layout of the existing house, and whether you are adding square footage or reworking what is already there. Our design build services in Scarborough start with a feasibility review that locks which of those drivers apply to your lot before design fees are spent.

A worked example on a 1960s Scarborough bungalow

Take a 1,200-square-foot 1965 bungalow in Tam O'Shanter on a 50-foot lot. The project is a 600-square-foot rear addition for a great room and primary suite, plus a main-floor renovation of the existing kitchen and bathroom. Total new and renovated area: 1,800 square feet. At $360 per square foot, construction comes to $648,000. Design and engineering at 6 per cent add $38,880. The building permit for this scope in Toronto typically runs $4,500 to $5,500. HST at 13 per cent on the full contract is $89,700. Contingency at 10 per cent of construction value is $64,800. Total budget: $845,880, or $470 per square foot when you divide by the total area being built or touched.

That second number, the all-in per square foot, is the one people forget when they compare quotes. A contractor quoting $320 per square foot is quoting construction only, and the client who budgets $576,000 for the 1,800 square feet is short by $270,000 once design, permits, tax and contingency land. The $360 construction figure in our example sits in the middle of the Scarborough range because the house is post-war (lower contingency, predictable framing), the lot is flat and the addition does not need a variance. A similar project on a Bluffs lot needing TRCA review and underpinning would push construction closer to $400 per square foot, and the all-in number past $500.

Design fees, permits and HST: the line items people forget

Design and engineering fees in Scarborough total 6 to 12 per cent of construction value, with the percentage dropping as project size grows. A $400,000 renovation might see 8 per cent in design fees; a $1.2 million rebuild might see 5 per cent. Those fees cover architectural drawings, structural engineering stamps, HVAC design, arborist reports if the lot has protected trees, and the permit coordination itself. On a design build contract, the fee is part of the single price, and the designer is pricing the construction live, so over-budget surprises at tender do not happen.

Building permit fees in Toronto for a whole-home renovation or addition usually land between $2,000 and $6,000, depending on the square footage and the number of inspections the scope will trigger. A variance application to the Committee of Adjustment costs several thousand dollars in City fees, plus $3,000 to $10,000 for the supporting reports (survey, planning rationale, sometimes elevation drawings for context), and the hearing takes three to six months. TRCA permits for regulated lots add their own fees and four to eight weeks when run concurrently with the City file. HST at 13 per cent applies to the entire contract, design and construction together, and it is not optional. A $600,000 construction contract becomes $678,000 after tax, and that $78,000 is due as the invoices are paid.

What moves the cost up or down in Scarborough

The biggest single variable is whether you are adding square footage or renovating within the existing walls. An addition means footings, framing, roofing, siding, windows and tying into the existing structure, all of which cost more per square foot than gutting and refinishing an interior. A 400-square-foot addition in Scarborough runs $180,000 to $200,000 in construction alone, or $450 to $500 per square foot, while a main-floor gut of the same area might run $110,000 to $140,000, or $275 to $350 per square foot.

Site conditions are the second lever. A flat Agincourt lot with no protected trees, no variances needed and no TRCA overlay is the baseline. A Bluffs property inside the hazard setback adds TRCA permit time and usually geotechnical investigation costs. A ravine lot in Highland Creek or along the Rouge adds both TRCA and tree protection costs, and grading restrictions that sometimes force the design onto piles or helical piers instead of strip footings. Underpinning a basement to gain headroom costs $400 to $600 per linear foot of foundation wall in 2026, and semi-detached underpinning needs engineering for the shared wall and formal notice to the neighbour, which adds time and sometimes negotiation costs.

Finishes are the third lever, but the range is narrower than people expect. Builder-grade finishes (laminate counters, vinyl plank, basic tile) might save 8 to 12 per cent against mid-range finishes (quartz, engineered hardwood, porcelain tile). Custom millwork, stone counters, high-end appliances and imported tile can add 15 to 25 per cent to the construction budget, but they do not double it. The Scarborough Bluffs Terrace project we completed in 2025 used mid-range finishes throughout and came in at $358 per square foot for a complex TRCA-regulated addition, which shows that site and permit complexity move the number more than the countertop choice does.

How Scarborough's housing stock affects your budget

Scarborough's housing is mostly post-war: 1950s and 1960s bungalows and split-levels in Guildwood, Cliffcrest and Agincourt, 1970s two-storeys in Highland Creek and Centennial, built on 40 to 60 foot lots with simple framing and poured-concrete or block foundations. That stock is easier and cheaper to renovate than the Victorian and Edwardian houses in the central city. Post-war framing is predictable, floor joists are usually 16 inches on centre, and the foundations are in better shape than pre-war rubble stone. Contingency on a 1960s Scarborough bungalow is 10 per cent of construction value, compared to 12 to 15 per cent on a century home in the Beach or High Park.

The lot pattern also helps. Scarborough lots are wider and deeper than most of the old city, so side-yard setbacks are less likely to kill an addition, and rear-yard depth gives room for a walkout or a deck without a variance. The zoning bylaw still caps floor space index around 0.6 times lot area in many neighbourhoods, so a 5,000-square-foot lot can usually support a 3,000-square-foot house, but the geometry is friendlier than it is on a 25-foot-wide lot in Leslieville. Properties along the Bluffs face shoreline erosion setbacks and TRCA review, which narrows the buildable envelope and adds permit time, but the rest of Scarborough's residential fabric is relatively straightforward from a zoning perspective.

Contingency and change orders: what to set aside

Contingency is the money set aside for conditions you discover when the walls come down: rot in rim joists, undersized wiring, a cracked drain stack, a footing that stops short of frost depth. On a post-war Scarborough house, 10 per cent of the construction budget is the standard contingency. On a pre-war house, 12 to 15 per cent. On a project that includes underpinning or a basement lowering, 12 per cent minimum, because soil conditions vary and neighbouring foundation movement sometimes forces mid-job design changes. A $500,000 construction contract needs a $50,000 contingency line, and that money should sit in the project account from day one, not be borrowed from the finish budget when a problem appears.

Change orders are different from contingency draws. A change order is a scope addition the client requests after the contract is signed: moving a door, adding a skylight, upgrading the tile. Those changes cost more per square foot than they would have if designed in from the start, because the schedule is set and trades have to return or adjust their sequencing. We track change orders separately and require written approval before the work is done, so there is no surprise invoice at the end. The projects that finish on budget are the ones where the client makes finish and layout decisions during design, not during framing, and where the contingency is sized honestly for the house and the scope. Design build timelines in the GTA depend as much on decision discipline as they do on permit speed.

One opinion: if you are within $50,000 of your maximum budget and the project needs a variance or underpinning, wait and save more money. Variance hearings can take six months, and underpinning costs vary with soil conditions that are not fully known until excavation starts. A contingency that is too small turns into value engineering during construction, which means cheaper finishes than you planned or a scope cut that leaves the house half-renovated. We would rather delay a start date by six months than watch a client run out of budget in month eight. The math on how site constraints affect design build applies here: the tighter the budget, the more the site and permit unknowns hurt.