---
title: "Basement Renovations and Legal Second Units"
url: "https://www.jarviscontracting.ca/basement-renovations"
description: "Basement finishing and legal basement apartments in Durham Region and the GTA: 2026 costs, the Building Code rules for second units, and how we build them."
publisher: "Jarvis Contracting"
---
# Basement renovations

Finished basements and legal second units, built to the code the inspector checks.

We price basement finishing at about $55 to $90 per square foot in 2026, and a full legal basement apartment at $80,000 to $180,000, before HST. A legal unit has to meet the Ontario Building Code's rules for secondary suites, such as a 1.95 m ceiling and a fire separation between the units, and pass your town's inspections.

## What's included

1. A check of ceiling height, exits and windows before design
2. Floor plans and finishes with our designer
3. Permit drawings, and the application for a second unit
4. Fire separation and sound between units
5. Egress windows and separate entrances
6. Bathrooms, wet bars and laundry

The kinds of job:

- Basement finishing: rec rooms, bedrooms, bathrooms, bars and laundry
- Legal second units
- Separate entrances and walkouts
- Opening up a basement by moving walls

## Typical duration

Set after the first site visit.

## Permits involved

- A building permit for a second unit, and for plumbing or structural work
- The Building Code's secondary-suite rules: ceiling heights and a fire separation between units
- Registration of the unit where the town requires it, such as Whitby
- No development charges for a second or third unit in an existing house
- Electrical work by a licensed electrical contractor, who files a notification with the Electrical Safety Authority

## What it costs

| Work | Range (CAD) | Basis | Source |
|---|---|---|---|
| Full legal basement apartment | 80000 to 180000 | 2026. Before 13% HST. | Our 2026 price |
| Basement bathroom | 25000 to 50000 | 2026; the top end when new plumbing goes under the slab. Before 13% HST. | Our 2026 price |
| Basement finishing | 55 to 90 per sq ft | 2026, by finish level. Before 13% HST. | Our 2026 price |
| Legalising an already-finished basement | 45000 to 95000 | 2026. Before 13% HST. | Our 2026 price |
| Separate side-door entrance | 18000 to 28000 | 2026. Before 13% HST. | Our 2026 price |
| Underpinning the full perimeter | 60000 to 120000 | 2026, when the ceiling is too low. Before 13% HST. | Our 2026 price |

What moves the number:
- Ceiling height, and whether the floor has to be lowered or underpinned
- A second unit or not: fire separation, a second exit, a kitchen
- A separate entrance or a walkout
- Bathrooms and how far the plumbing runs
- Moisture or water damage found when the walls open
- Finish level, and 13% HST on top

## Finished jobs

- [Stone Ridge: a finished basement in Scarborough](https://www.jarviscontracting.ca/projects/stone-ridge): Scarborough, Toronto. Full basement finish: rec room, media wall, arched wet bar, bathroom, laundry room and bedroom.
- [Forest Ridge: a finished basement with a bar and media wall](https://www.jarviscontracting.ca/projects/forest-ridge). A finished lower level with a bar, fireplace wall and built-in shelving.
- [Greenwood: a new top storey and rear extension in Toronto](https://www.jarviscontracting.ca/projects/greenwood): Toronto, 2026. Top floor replaced with a new storey, rear extension, basement enlarged, full interior design and build.
- [Solace: a home gutted to the studs and rebuilt inside](https://www.jarviscontracting.ca/projects/solace): Toronto, 2026. Complete gut to the studs, load-bearing walls removed and reframed, spray foam throughout, new upstairs washroom, full interior design.
- [Syncopa: steel beams, a new layout and three new bathrooms](https://www.jarviscontracting.ca/projects/syncopa): North York, Toronto, 2026. Permits, steel beams, layout reworked, stone fireplace out, three new bathrooms, new doors, floors, trim and tile, attic insulation upgraded.
- [Bellamy: opening up a brick bungalow without an addition](https://www.jarviscontracting.ca/projects/bellamy): Scarborough, Toronto, 2025. Whole main floor: load-bearing walls out, steel beams in, new kitchen, mudroom, office, fireplace, floors, trim and doors.

## Is it legal, or just finished?

A finished basement is a renovation. A legal second unit is a permitted, inspected apartment that meets the Building Code's secondary-suite rules: ceilings at least 1.95 m, 1.85 m under beams and ducts, and a fire separation between the units, which can be a continuous smoke-tight layer of 15.9 mm Type X drywall ([2024 Building Code Compendium](https://www.publications.gov.on.ca/301880)). Turning one unit into two needs a permit even if you build nothing ([Building Code Act](https://www.ontario.ca/laws/statute/92b23)). Our [legal basement requirements guide](https://www.jarviscontracting.ca/guides/legal-basement-apartment-requirements-ontario) lists the rest.

## What does a legal basement apartment cost?

A full legal basement apartment runs $80,000 to $180,000 with us in 2026, and legalising a basement that's already finished about $45,000 to $95,000, before HST. A separate side entrance is about $18,000 to $28,000 on its own, and a bathroom $25,000 to $50,000, more when new plumbing goes under the slab. Our [legal basement cost guide](https://www.jarviscontracting.ca/guides/legal-basement-apartment-cost-ontario) breaks it down.

## Does a basement apartment pay development charges?

No. A second or third unit inside an existing house is exempt from development charges ([Development Charges Act](https://www.ontario.ca/laws/statute/97d27)). Some towns ask you to register it: Whitby charges $268 ([Town of Whitby](https://www.whitby.ca/services-and-payments/building-and-renovating/additional-dwelling-units/)).

## Do I need a permit to finish my basement?

Your town's building department decides, and the answer turns on what you're building: a second unit always needs one, and so does plumbing or structural work. Our [basement permit guide](https://www.jarviscontracting.ca/guides/basement-permits-durham-region) covers each Durham town.

## Real work

Stone Ridge, in Scarborough, is a finished basement with a rec room and panelled media wall, an arched wet bar, a bathroom, a laundry and a bedroom. One client, whose basement had been a storeroom for twenty years, wrote that the job "doubled the size of the living area in our home" (Tony O'Brien, Google review).

## Where we do this

Also in Ajax, Aurora, Brampton, Brock, Burlington, Caledon, Clarington, East Gwillimbury, Georgina, Halton Hills, King, Markham, Milton, Mississauga, Newmarket, Oakville, Oshawa, Pickering, Richmond Hill, Scarborough, Scugog, Toronto, Uxbridge, Vaughan, Whitby, Whitchurch-Stouffville.

## How the job runs

1. **Meet James.** James meets you at the house, hears what you want and gives you a rough estimate on the spot. The first estimate is free.
2. **Proposal and contract.** If the estimate works for you, James prepares a detailed proposal. The whole project is priced, and the contract signed with a 10% deposit, before any design work begins.
3. **Design onboarding.** Our designer sends you an onboarding email with some homework: your style, how your family uses the house, and what you need and want. You share Pinterest boards, then go through them together on a Zoom call: what you like in the pictures, and what you don't.
4. **Measure and floor plans.** The designer measures the house and draws the floor plan: which walls come out, where the stairs land, how new space joins the old. We go through it with you until it's confirmed.
5. **Drawings and 3D rendering.** With the plan confirmed, she draws the elevations and the millwork, then puts it all into a 3D rendering, so you see the rooms before anyone orders a cabinet.
6. **Finishes presentation.** We don't take you round the stores: there are too many options. Using what she learned in onboarding, the designer narrows the tile, flooring, quartz, plumbing fixtures and the rest to a few choices that suit your style, collects the samples and presents them to you in our office. If a selection changes the price, the change goes through a change order you sign.
7. **Permits and engineering.** We prepare the permit drawings, bring in the structural engineer wherever a beam or a load changes, and apply to the municipality. If the plan changes after the permit is issued, we file the amendment.
8. **Construction.** Our crew and trades build it, with one point of contact from demolition to the last coat of paint. Our site supervisors write a job log every day, which you can follow in our online app. When we open a wall and find a problem, you hear about it, and what it costs, before we fix it.
9. **Inspections.** The municipal building inspector checks the work at each stage the permit sets, before it gets covered up.
10. **Handover.** We walk the finished house with you and put right anything that isn't. On one job a stair stain didn't match the new floor, so we refinished the stairs.

## Credentials

- Written warranty: 1 year workmanship and materials, 2 years plumbing, heating, electrical and building envelope, 7 years structural
- BBB Accredited Business: Accredited by the Better Business Bureau since November 2025 (https://www.bbb.org/ca/on/ajax/profile/general-contractor/jarvis-contracting-inc-0107-1416595)
- Durham Region Home Builders' Association: Member, Renovators (https://www.drhba.com/Sys/PublicProfile/99587295/5125036)
- RenoMark: RenoMark renovator, through the DRHBA (https://renomark.ca/find-a-renovator/)

## Questions

### What makes a basement apartment legal in Ontario?

A legal basement apartment in Ontario has a building permit, passed its inspections and meets the Building Code's secondary-suite rules, including minimum ceiling heights and a fire separation between the units. Some towns, such as Whitby, also require the unit to be registered.

### What ceiling height does a basement apartment need in Ontario?

The 2024 Ontario Building Code requires ceilings of at least 1.95 m in a secondary suite, with at least 1.85 m of clear height under beams and ducts. Basements lower than that need the floor lowered or the walls underpinned before they can become a legal unit.

### How much does a legal basement apartment cost in Ontario?

We price a full legal basement apartment at $80,000 to $180,000 in 2026, and legalising an already-finished basement at about $45,000 to $95,000, before HST. A separate entrance adds about $18,000 to $28,000 on its own, and underpinning more again.

### Do I pay development charges on a basement apartment?

No. Ontario's Development Charges Act exempts a second or third unit created inside an existing house, within the three-unit limits. You still pay the building permit fee, and in towns like Whitby a registration fee of $268.

## Guides

- [Do you need a permit to finish a basement in Durham Region?](https://www.jarviscontracting.ca/guides/basement-permits-durham-region)
- [HCRA licence and Tarion warranty: who needs them in Ontario](https://www.jarviscontracting.ca/guides/hcra-and-tarion-explained)
- [How many units can I add to my lot in Ontario?](https://www.jarviscontracting.ca/guides/bill-23-additional-units-ontario)
- [Questions to ask a contractor in Ontario before you sign](https://www.jarviscontracting.ca/guides/questions-to-ask-a-contractor)
- [What does a legal basement apartment cost in Ontario in 2026?](https://www.jarviscontracting.ca/guides/legal-basement-apartment-cost-ontario)
- [What does a legal basement apartment need in Ontario?](https://www.jarviscontracting.ca/guides/legal-basement-apartment-requirements-ontario)
- [Whitby's ADU incentive: fees refunded for applications by 31 Dec 2026](https://www.jarviscontracting.ca/guides/whitby-adu-incentive)

## Sources

1. [2024 Building Code Compendium](https://www.publications.gov.on.ca/301880)
2. [Building Code Act](https://www.ontario.ca/laws/statute/92b23)
3. [Development Charges Act](https://www.ontario.ca/laws/statute/97d27)
4. [Town of Whitby](https://www.whitby.ca/services-and-payments/building-and-renovating/additional-dwelling-units/)