Do you need a permit to finish a basement?

The short answer

If you are building walls to create rooms, adding plumbing, changing windows or doing structural work, you almost certainly need a building permit. Swapping out carpet for vinyl plank usually does not.

The details depend on where you live. Below is what each municipality's official building page or guide says, with links so you can check for yourself. Pages change, so treat this as a starting point and confirm with the building department.

Ontario Building Code basics

Building permits in Ontario are issued under the Building Code Act and reviewed against the Ontario Building Code. A new edition, the 2024 Ontario Building Code, took effect on January 1, 2025.

Older homes get some flexibility. The City of Peterborough's Basement Finishing Guide explains that homes less than five years old must conform to Part 9 of the Code, while homes five years or older may conform to Part 11, which covers renovations to existing buildings. Your building department will tell you which rules apply.

City of Kawartha Lakes (Lindsay)

The City's Building, Septic and Renovations page lists "Creation of rooms in a basement" as work that needs a permit. So do the addition of a basement entrance, alteration or addition of any plumbing, structural alterations and changes to building systems such as insulation. Replacing non-fire-separation drywall or flooring is listed as not needing a permit.

Basement projects apply under the "Renovation to Residential" category on the Building Permits and Guides page. Homes on private septic may also need a septic review. The Building and Septic Division can be reached at 705-324-9411 ext. 1288.

Township of Scugog (Port Perry)

Scugog's Building Permits page does not name basement finishing directly. Its list of typical permit projects includes adding a bedroom, making a new window opening, making structural changes, and installing or altering plumbing. The Township says the list is not complete and asks residents to contact the Building Department at 905-985-7346 ext. 169.

City of Oshawa

Oshawa's Basement Renovations page says renovations that alter the interior of the home usually require a building permit, including finishing basements. The City's Basement Renovation Guide says a permit is required for alterations to existing basements, except replacing floor finishes, installing cabinetry with no plumbing changes, and replacing a window within the existing rough opening.

Town of Whitby

Whitby's Building Permits page lists "finished basements" as needing a permit, along with basement walkouts, plumbing and heating systems, adding or removing walls, and structural alterations such as adding windows or doors.

Town of Ajax

Ajax's Building Permits and Inspections page includes finished basements among its common residential permit guides. The Town's Finished Basements guide lists what plans must show, including room uses, ceiling heights, insulation, windows, plumbing fixtures and smoke and carbon monoxide alarms.

City of Pickering

Pickering's Building Permits page lists "finishing a basement" as needing a permit. It also notes that a change of use needs a permit even with no construction, giving a basement den to bedroom as an example. Basement waterproofing repairs and sump pumps are listed as not needing a permit.

Municipality of Clarington

Clarington's Building and Demolition Permits page says permits are normally required for partitioning a basement or adding a basement entrance, structural alterations and altering or adding any plumbing. It says permits are not normally required for new interior wall, floor or ceiling finishes or basement waterproofing repairs. A basement finish that adds walls or plumbing will usually need one, so check your plans with the building division.

City of Peterborough

Peterborough's Basement Finishing Guide says a building permit is required for any construction in your basement, including drywall work and moving or installing plumbing fixtures.

Electrical work and the ESA

A building permit does not cover wiring. The Electrical Safety Authority says the Ontario Electrical Safety Code requires almost all electrical work to be reported by filing a notification of work, and that having a building permit is not the same thing. You may need both.

ESA also says that if you hire someone to do electrical work in your home, by law it must be a Licensed Electrical Contractor. The contractor files the notification and requests the inspection.

Do you need drawings or a BCIN designer?

Most municipalities want scaled drawings showing existing and proposed layouts, room uses, windows, insulation and alarm locations. Oshawa's guide asks for a site plan, floor plans and a wall section, and an elevation where a window or door opening changes.

Who can draw the plans matters. Peterborough's guide says the homeowner on title may prepare the drawings. Otherwise, the work must be designed by a ministry-qualified designer holding at least a BCIN House qualification. Ajax notes that plans can be prepared by the owner, a qualified designer, an architect, an engineer or a mix, depending on the work. Structural changes such as removing a bearing wall or cutting a new opening may need an engineer.

Work that usually does not need a permit

Several municipalities list these as not usually needing a building permit. Confirm locally, since each list is different.

• Replacing flooring such as carpet, tile or vinyl
• Installing cabinets with no plumbing changes
• Replacing a window in the same opening with no framing changes
• Some basement waterproofing repairs (listed by Pickering and Clarington)
• Painting and other cosmetic work

Plan your basement with Oakridge

At a free site meeting, Oakridge reviews your basement and talks through which approvals your plan is likely to involve. Any permit services and fees are written into the project scope, so you know who handles what. Call 289-731-2086 or request a free site meeting online.