Do you need a permit to finish a basement in Durham Region?

Yes. Ontario's Building Code Act requires a building permit to finish a basement in every town in Durham Region, Ontario. The Code's only small-project exemption is for sheds. As of October 2026, the permit fee for a 700 sq ft basement works out to about $356 in Clarington and up to $693 in Whitby on each town's 2026 schedule, and Pickering adds a $1,000 refundable deposit.

Key takeaways

• A permit is required to construct under section 8 of the Building Code Act, and the Code exempts only sheds up to 15 m² with no plumbing (Div. C 1.3.1.1.(6), 2024 Building Code).
• Oshawa prints its own basement line, $7.79 per m² charged on at least 50 m², per its 2026 fee by-law.
• Pickering charges $7.37 per m² for finished basements plus a $1,000 refundable performance deposit, effective 6 January 2026, per its 2026 user fees.
• Starting before you apply costs the greater of $100 or 25% of the fee in Whitby, per Schedule N, and 50% extra in Oshawa and Clarington.
• The Code gives the town 10 business days to decide a complete permit for a single-unit house, and likely 15 for a house with a basement apartment (2024 Building Code).

Do you need a permit to finish a basement in Durham Region?

You do, in Whitby, Oshawa, Ajax, Pickering and Clarington alike. Section 8 of the Building Code Act says no one may construct without a permit, and the 2024 Building Code doesn't exempt basement finishing, interior alterations, decks or garages. Its one homeowner-sized exemption is a one-storey storage shed of up to 15 m² with no plumbing (Div. C 1.3.1.1.(6)).

In practice, framing walls, adding a bathroom, moving plumbing, removing or adding a wall, or adding a bedroom all fall inside "construct". So does cutting a new entrance or enlarging a window. Electrical work is separate: a Licensed Electrical Contractor files a notification with the Electrical Safety Authority before starting, and that's in addition to the building permit.

If the basement will become a separate unit, the permit is needed even if you build almost nothing. Section 10 of the Building Code Act covers a change of use that increases the hazard, and the Code lists converting one dwelling unit into more than one as exactly that (Div. C 1.3.1.4.(1)(b)). The Code rules for a second unit are in our requirements guide.

What does a basement permit cost in each Durham town?

Only two of the five lakeshore towns name basements in their fee schedules, so for the other three you have to infer which line applies. As of October 2026, here's the floor-area rate each town's 2026 schedule supports and what it works out to on a 700 sq ft (65.0 m²) basement:

Note: these are our area-times-rate calculations, not quotes from the towns; the building department sets the final fee, and Oshawa's and Clarington's by-laws provide for 3% increases each 1 January.

Be careful with Whitby, Ajax and Clarington. Whitby's Schedule N has no separate basement line, so the $10.65 interior alteration rate is the likely fit, but the schedule doesn't say so. Ajax's schedule has no explicit basement line either, and the schedule doesn't print the unit beside every rate, though per m² is the likely reading. Clarington's by-law has an interior alteration rate but no line that names basements. Call the building division and ask which line they'll use before you budget on our number.

Pickering's line is the clearest: its "Interior Partitioning and Finishing" rate names apartments in houses and finished basements. Oshawa's 50 m² floor means a small basement still pays at least $390 (our calculation: 50 m² at $7.79).

What changes if the basement becomes an apartment?

The fee line changes, and most towns add a flat charge for a new entrance below grade. As of October 2026, here's what the same five schedules charge when the basement is a second unit:

Note: these figures cover the building permit only; registration, a minor variance or a curb cut are separate charges where they apply.

Ajax also lists a $146 flat fee for a "retrofit accessory apartment" (B4) on the same schedule; ask the Town whether your project fits it. In Whitby, the Housing Accelerator Fund incentive reimburses the ADU permit fee and the below-grade entrance fee for complete applications made by 31 December 2026. Our Whitby ADU incentive guide has the dates, and the cost guide puts these fees next to the build cost.

What happens if you start without a permit?

You pay a surcharge on top of the fee, and you may have to open finished walls so an inspector can see the framing, insulation and plumbing behind them. The surcharge is the smaller cost. As of October 2026:

• Whitby: work started before a permit application costs the greater of $100 or 25% of the application fee, per Schedule N. On a $693 basement permit that's $173 more (our calculation).
• Oshawa: 25% extra if work began after you applied but before the permit, and 50% if you never applied, per its fee by-law. On a $507 basement permit, 50% is about $254.
• Clarington: the same 25% and 50% surcharges, per By-law 2024-006.
• Ajax and Pickering: our research didn't confirm a surcharge rate for either. Ask the building department rather than assume there isn't one.

The bigger risk is the drywall. A basement finished without a permit can't show its framing, vapour barrier or drain lines to an inspector, so legalising it later usually means cutting the finish open. For scale, we price legalising an already finished basement at $45,000 to $95,000 before HST in 2026.

What is Pickering's $1,000 basement deposit?

It's a refundable performance deposit the City added on 6 January 2026 for finished basements, secondary suites and basement walk-ups, per its 2026 user fees. You pay it with the permit and get it back later, so budget the cash even though it isn't a cost. Ask the City what releases it before you apply.

The same schedule has a separate, larger deposit line for new houses and some additions, so a basement job done alongside an addition may fall under different rules. Pickering is the only one of the five towns where we found a basement deposit.

How long does a basement permit take in Durham?

The Code sets the clock, and it only starts once your application is complete. For a house where no dwelling unit sits above another, the chief building official has 10 days to issue the permit or refuse it in writing with reasons, under Div. C 1.3.1.3. of the 2024 Building Code. Those days don't count Saturdays, holidays or days the office is closed (1.3.1.3.(8)). A house with a basement apartment likely falls in the 15-day category. An incomplete application has no clock running at all.

Oshawa warns on its building permits page that "we cannot guarantee review timeframes will be met" because of record volume. Plan for some slack in any town, and don't book trades for the day after you apply.

How we handle basement permits

We're Jarvis Contracting, a family design-build firm based in Ajax. James Jarvis runs construction and his wife, Ceara Jarvis, runs design through her studio Juliette Interiors. We draw permit drawings in-house and build basements and additional units, so the drawings the town reviews are the ones our crew builds from. We plan, draw and build to the Ontario Building Code; the town reviews the drawings and inspects the work.

On a permitted job the walls stay open until the town's framing and insulation inspections pass, and we schedule the trades around those visits. See our basement renovations page for how a basement job runs from measurement to final inspection.

Questions

Do I need a permit to finish a basement in Whitby?

Finishing a basement in Whitby needs a building permit, because Ontario's Building Code Act requires a permit to construct and the Code doesn't exempt basement work. Whitby's 2026 Schedule N has no separate basement line; the $10.65 per m² interior alteration rate likely applies, which is about $693 for 700 sq ft by our calculation.

How much is a basement finishing permit in Oshawa?

Oshawa charges $7.79 per m² to finish a basement in 2026, on the greater of the actual floor area or 50 m². A 700 sq ft basement works out to about $507 by our calculation, and the minimum for any basement is about $390. Oshawa raised its fees 3% on 1 January 2026.

Does Ajax charge a separate fee for a basement entrance?

Ajax charges for a basement entrance separately. Its 2026 Schedule A lists a $329 fee for a below-grade entrance (line B10), separate from the floor-area fee. Ajax doesn't print an explicit basement finishing line, so ask the Town whether the $7.16 interior alteration rate (B5) applies to your basement.

What is the $1,000 deposit for a basement permit in Pickering?

Pickering's $1,000 basement deposit is a refundable performance deposit, effective 6 January 2026, charged on finished basements, secondary suites and basement walk-ups. It's on top of the $7.37 per m² permit fee. Ask the City what's needed to release it before you apply.

Do I need a permit to finish a basement in Clarington?

A basement finish in Clarington needs a building permit, like anywhere in Ontario. Clarington has no named basement line in By-law 2024-006, so the $5.48 per m² interior alteration rate likely applies, about $356 for 700 sq ft by our calculation, and the rate rises 3% each 1 January.

What happens if I finished my basement without a permit in Durham Region?

A basement finished without a permit in Durham Region can draw a surcharge when you do apply: 50% of the fee in Oshawa and Clarington if no application was made, and the greater of $100 or 25% in Whitby. The larger cost is usually opening walls so the framing, insulation and plumbing can be inspected.

Sources

1. Building Code Act ontario.ca
2. 2024 Building Code publications.gov.on.ca
3. 2026 fee by-law media-002-ca.cdn.govstack.com
4. 2026 user fees corporate.pickering.ca
5. Schedule N media-003-ca.cdn.govstack.com
6. Electrical Safety Authority esasafe.com
7. Ajax Schedule A, 2026 ajax.ca
8. Clarington fee by-law 2024-006 weblink.clarington.net
9. building permits page oshawa.ca