Mississauga Building Permits: What Needs One, What Costs What

Mississauga requires a building permit to finish a basement, to replace a furnace with a higher-efficiency model and for a deck more than 0.61 metres above grade. Most fees are a rate per square metre with a floor under them: no residential permit inside Part 9 of the Building Code costs less than $244.00, and none outside Part 9 less than $386.00. But two classes, interior alterations and additional residential units, charge the rate plus that minimum. A basement finish in a detached, semi, townhouse or duplex is $5.64 per square metre, an interior alteration $6.84, a heated addition $13.96. Allow 7 to 10 business days for pre-screening and 10 business days for a first residential review.

What needs a permit in Mississauga

These come from the City's list of projects that require a permit: "a list of common projects", in its words, not the full set.

Outside: an addition or balcony; a deck greater than 0.61 metres (2 feet) high and any covered porch; a shed greater than 15 square metres, or one of any size with plumbing; a gazebo greater than 10 square metres, and any other structure over 10; a detached garage; re-cladding with new material; solar panels.

Inside: finishing a basement to create rooms or living space, a basement apartment, a below-grade entrance or walkout; interior alterations, dormers, skylights; a new window or door opening; roof alterations that change the height or slope; changing a building's use; fire damage repair.

Mechanical and plumbing: a furnace replacement that's of a higher efficiency than existing, and altered ducts; an HVAC or geothermal system; a plumbing fixture added, removed or relocated; a backwater valve or backflow preventer.

What is exempt

The same page lists what you can build without one (common projects only). Toronto is blunter: its list "is not exhaustive and judgment should be used". Absence from it is not permission.

• A deck less than 600 mm (2 feet) in height: note the trigger is written as more than 0.61 metres and the exemption as less than 600 mm, a 10 mm sliver between the rules; if your deck lands in it, call 311.
• A shed less than 15 square metres, if it is one storey, free-standing, has no plumbing and is for storage only.
• A gazebo 10 square metres or less; a retaining wall less than one metre high; re-shingling a roof.
• Re-cladding with the same material; replacing a window, door or plumbing fixture with one the same size in the same place.
• A decorative gas fireplace, sump pump, concrete pad, fence, landscaping, painting and cabinetry.

How the fee is calculated

Schedule A of the Building By-law gives one formula: Permit Fee = SI × A, where SI is the service index for the class of work and A is the floor area in square metres. Floor area is "measured to the outer face of exterior walls and to the centre of party walls or demising walls, except when calculating interior partition work, and shall include all levels of the building". So a semi or townhouse is measured to the middle of the party wall, and a two-storey addition is charged on both storeys.

Then the floor: residential projects within Division B, Part 9 of the Building Code "shall be no less than $244.00", anything outside Part 9 "no less than $386.00", and clause 1(o) adds that "unless authorized elsewhere in this By-law, at no time shall the fees be less than the minimum fees". Separately, the fee for the electronic pre-screening of applications shall be $50.00, non-refundable. But the City credits it towards the total cost of your permit, so it comes off the bill rather than adding to it. Section 48 re-indexes the schedules every February 1.

Two classes are charged differently. In Schedule B, interior alterations, partitioning and a change of occupancy classification carry the qualifier "(plus the minimum applicable fee)", as does an additional residential unit inside an existing building. For those, the minimum is added to the rate rather than acting as a floor under it.

Worked examples

Finishing a 70 square metre basement in a detached house: 70 × $5.64 = $394.80, which clears the $244.00 floor, and the $50.00 paid at submission is credited against it. Shrink the job and the floor takes over: 30 × $5.64 = $169.20, so a 30 square metre finish costs $244.00.

A 40 square metre interior alteration in a house (a kitchen gut or a wall removal) is the additive class: (40 × $6.84) + $244.00 = $517.60, not the $273.60 a floor model gives. Clause 1(h) measures A here as "the area contained within a rectangle encompassing the partitions being erected", not the whole floor. The same job in a condo apartment is Group C but outside Part 9, so the minimum is $386.00: (40 × $6.84) + $386.00 = $659.60.

A two-storey rear addition with a 35 square metre footprint is charged on both levels, so A is 70 square metres: 70 × $13.96 = $977.20. A raised deck off the back adds a flat $244.00: $977.20 + $244.00 = $1,221.20. Clause 1(e) waives those extras only where they are built with the single dwelling they serve. An addition is not.

Schedule B prices residential plumbing fixtures at $42.23 each, labelled "(Plumbing review only)": a three-piece bathroom is 3 × $42.23 = $126.69. Whether that is charged on top of a permit already covering the work is not stated, so ask at pre-screen. A material change to reviewed drawings is billed at $159.00 per hour.

How long it takes

The City's published time frames run in two stages inside the ePlans portal.

Pre-screen: 7 to 10 business days. The City checks the minimum requirements are present before charging anything beyond the $50.00, and you cannot upload or answer comments meanwhile.

First department review, once the application is deemed complete: 10 business days for residential, 15 business days for a second unit, 20 business days for non-residential.

Incomplete applications are not subject to those timelines, and resubmissions have no guaranteed review time: each cycle adds two or more weeks. The City's averages for the whole process are 13 weeks for a new detached or semi, 7 weeks for a residential alteration (detached, semi) and 10 weeks for a second unit.

If you cancel, Schedule A refunds 85% before departmental review starts, 65% after it begins and 45% once the permit is issued, less 5% per inspection conducted.

Inspections are yours to book

Inspections are mandatory for all construction, renovation, demolition and change-of-use work, and nobody books them for you: use the building permit application number and WEB ID on your permit notice. They run Monday to Friday, 8:30 a.m. to 4:30 p.m.

Book an initial site inspection before starting any construction work. It tells you which inspections your project needs and in what order. After that: book before you cover work up with insulation, drywall, gravel or concrete, and pass one stage before starting the next. Schedule D lists the prescribed notices: footing, backfill, framing, HVAC and plumbing rough-ins, insulation, fire separations and the finals. Keep the permit card visible and the drawings on site at 11×17 inches or larger.

Where Mississauga differs from Toronto

Two Mississauga requirements are broader than Toronto's.

Basements. Toronto exempts finishing a basement in a house where the work involves no structural or material alterations, creates no second unit and adds no new plumbing. Mississauga lists "finishing a basement to create rooms or living space" as needing a permit, full stop, at $5.64 per square metre in a house.

Furnaces. Toronto's exemption list includes "replacing a furnace or boiler in a house"; Mississauga requires a permit for a replacement of higher efficiency than the existing furnace, a flat $244.00.

The money differs less. Toronto's minimum fee is $214.79 (2026) for all work against Mississauga's $244.00, and $18.56 per square metre for single family dwellings, semis, townhouses and duplexes against Mississauga's $18.99. Toronto also adds a residential unit fee of $56.33 per new unit. Thresholds mostly match: a deck needs a permit above 60 cm (24 inches) in Toronto and above 0.61 metres in Mississauga, and both exempt sheds under 15 square metres.

Second units and garden suites: the fee comes back

For an additional residential unit you build or legalise, Mississauga refunds the permit fee: it is automatically refunded after the ARU is constructed and all building inspections are completed, by cheque. Second and third units are exempt from most municipal charges too. Two costs are not: a garden suite needs a new municipal address at $81.90 plus HST, and development charges apply to additions and garden suites.

Registration is separate and free: every second unit must be registered under the Second Units Registration By-law, which wants proof of ownership and the permit signed off by all concerned inspectors.

If you start before the permit is issued

Section 50 makes anyone who begins construction, demolition or a change of use before a permit is issued liable for an additional fee on top of any penalty under the Building Code Act. Section 51 puts a number on it: where work started first and an order to comply follows, an additional 40% of the permit fee applies, to a maximum of $5,000.00, payable on issuance. Fire damage repair is the carve-out, and discharging that order from your title later costs a non-refundable $618.

Section 56 sends the penalty itself to Section 36 of the Building Code Act. A City of Toronto audit quotes subsections 36(3) and (4): on conviction a person faces a fine of not more than $50,000 for a first offence and $100,000 for a subsequent one; a corporation, $500,000 and $1,500,000. The Act sets those ceilings; a justice of the peace sets the fine within them.