# Egress Window Requirements in Ontario: What the Building Code Actually Says

> In Ontario, every bedroom in a basement apartment needs an egress window with at least 0.35 m² (3.8 sq ft) of unobstructed clear opening, no dimension smaller than 380 mm (15 in), that can be opened from inside without tools, keys or special knowledge. If the window sits below grade, the window well must give at least 760 mm (30 in) of clearance in front of the sash. For a suite in an existing house, the sill should be no more than 1.5 m above the floor. Cutting the opening, excavating and draining the well and installing the window costs $2,500–$5,500 per bedroom in Toronto.

*Category: underpinning | 7 min read | Updated 2026-10-01*

## What an egress window is for

An egress window is a second way out of a bedroom when the door is blocked by fire — and a way in for a firefighter. The Ontario Building Code (OBC) treats it as life-safety equipment, which is why it is one of the inspections a basement apartment cannot skip and one of the most common reasons a suite fails its first inspection. Ordinary basement windows almost never qualify: the typical 1970s hopper window gives a clear opening of roughly 0.15 m², less than half the minimum.

## The four numbers inspectors check

| Requirement | Ontario Building Code minimum | What it means on site |
| --- | --- | --- |
| Clear opening area | 0.35 m² (3.8 sq ft) | Measured with the sash fully open — frame and sash are not counted |
| Smallest dimension | 380 mm (15 in) | A long, thin slot does not pass even if the area does |
| Operation | Openable from inside without tools, keys or special knowledge | No padlocked bars; security bars must have an interior quick-release |
| Window well clearance | 760 mm (30 in) in front of the window | Measured from the glass to the well wall; deeper wells need a way to climb out |

For a secondary suite in an existing house, the Code's Part 11 compliance alternatives add a practical limit: the bottom of the opening should be no more than 1.5 m (about 5 ft) above the floor, so an occupant can get out without a ladder. Casement windows are the usual answer in a basement because the whole sash swings clear; a slider or hopper has to be much larger to reach the same clear area.

## Which rooms need one

- Every bedroom in the suite — including a den or office that could be used as a bedroom; inspectors look at the room, not the label on the drawing.
- Not required where the bedroom has a door that opens directly to the outside.
- Not required where the suite is protected by a sprinkler system (rare in houses, common in purpose-built units).
- Living rooms and kitchens are not required to have egress windows, though the suite as a whole still needs its separate entrance.

## How an egress window is installed in a Toronto basement

1. Locate services. We scan for the weeping tile, gas line, hydro feed and any buried drains along the wall before any digging.
2. Excavate the well. The hole goes a few inches below the new sill so the well drain sits under the window, and wide enough for the 760 mm clearance plus the well itself.
3. Cut the opening. Concrete or block is saw-cut to the new rough opening; in a poured wall over about 1.2 m wide, an engineered lintel is added above.
4. Drain the well. A drain tied into the weeping tile (or a dry well where there is none) keeps the well from filling with water and leaking through the new window.
5. Install and flash. The window is set, foamed, flashed and sealed; the well is set against the wall and back-filled with clear stone.
6. Finish inside. Jamb extensions, trim and, in a suite, a fire-rated return if the window sits in a rated assembly.

## What it costs

In Toronto and the GTA, a complete egress window — cutting the opening, the engineered lintel where needed, excavation, well, drain, the window itself and interior finishing — runs $2,500–$5,500 per window in 2026. The low end is a block wall with easy access and a standard well; the high end is a poured wall in a tight side yard where spoil leaves by hand. Add $800–$1,500 for a well cover, which is worth it for anything deeper than about 1 m.

> Do egress windows at the same time as underpinning or waterproofing. The excavation and the drain tie-in are already open, and the engineering drawings already cover the wall — on its own, the same window costs 25–40% more.

**Q: Does a basement apartment need an egress window in every room?**

No — in every bedroom. A living room or kitchen does not require one. A room shown as a den or office is treated as a bedroom if it could reasonably be used as one, so plan the egress window rather than argue the label.

**Q: Can I use a window well ladder instead of a bigger well?**

The 760 mm clearance is required regardless. A ladder or steps are added on top of that when the well is deep enough that climbing out would otherwise be difficult. Grated covers are allowed as long as they can be pushed open from inside the well without tools.

**Q: Is a 24 x 36 inch window big enough for egress?**

Only if its clear opening — not its frame size — reaches 0.35 m² with no side under 380 mm. A 24 x 36 casement that opens fully usually passes; a 24 x 36 slider opens only half its width and usually fails. Measure the open sash, not the glass.

**Q: Do I need a permit to install an egress window?**

Yes. Cutting a new or larger opening in a foundation wall is structural work and needs a building permit in every GTA municipality, and the window is inspected as part of a secondary-suite permit. Replacing an existing window with a same-size unit usually does not.

## Related Services
- [Basement Apartment Conversion](https://buildoreno.ca/underpinning/basement-apartment)
- [Basement Waterproofing](https://buildoreno.ca/underpinning/waterproofing)
- [Underpinning Services](https://buildoreno.ca/underpinning)

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