In short
- The City of Ottawa's August 2025 advisory sets an egress window opening of at least 0.35 m² with no dimension under 380 mm, openable from inside without tools.
- The window well needs 550 mm of clearance in front, and a well deeper than 1000 mm needs a way to climb out.
- HomeStars prices a cut-in egress window in Ottawa at $3,500–$6,000 each, and a basement bedroom addition at $15,000–$30,000.
- The sill height cap of 1000 mm does not apply to basement areas.
- Before a basement bedroom is slept in, Health Canada wants a long radon test: three months or more, during the heating season.
Typical prices in Ottawa
| Job | Typical range | Notes |
|---|---|---|
| Egress window, foundation cut and install | $3,500–$6,000 each | HomeStars Ottawa, 2026; frost-line depth and foundation work drive it |
| Basement bedroom addition | $15,000–$30,000 | Framing, insulation, drywall, flooring, electrical and one egress window |
| Building permit, renovation | $12.75 per $1,000 | Minimum $117, City fee schedule dated January 1, 2026 |
Sources. Seen 29.10.2026: City of Ottawa Building Code Services, Advisory: Egress windows for floor levels containing a bedroom (August 2025, 2024 Ontario Building Code). HomeStars, 2026 Basement Renovation Cost Guide for Ottawa. City of Ottawa, Finishing a basement. City of Ottawa, Comprehensive Building Code Fee Schedule. Health Canada, Guide for radon measurements in homes. Ontario, Add a second unit to your house. Ontario Association of Fire Chiefs, Fire Code carbon-monoxide update.
Why a basement bedroom needs its own window
A bedroom below grade has to give the sleeper a way out that does not depend on the stairs. The Ontario Building Code names that way in article 9.9.10.1, and the City of Ottawa’s Building Code Services published an advisory in August 2025 that explains how it applies the article under the 2024 code. The rule covers floor areas that serve a bedroom.
If the basement already has a window in the right spot, the company measures it. Many older Ottawa basement windows are small, set high in the wall and do not open wide enough.
The measurements the City applies
From the advisory, when the window is fully open:
- an unobstructed opening of at least 0.35 m² with no dimension under 380 mm;
- openable from inside without tools, and it holds the opening without extra support;
- no cap on sill height in basement areas (elsewhere the cap is 1000 mm); stairs, built-in cabinets or counters can reach a high sill;
- 550 mm of clearance in front of the window, with a way to keep going out of the well.
Where the well is deeper than 1000 mm, the occupant needs help to climb out, such as a ladder or built-in steps. For built-in cabinets under the window, the City recommends no more than 1000 mm from the cabinet top to the window.
Cutting the foundation
Putting a new window into a foundation wall means cutting concrete or block, framing a header, setting the window, building a well and draining it. HomeStars’ Ottawa guide puts that at $3,500 to $6,000 per window and ties the figure to the frost line depth and the foundation work. A basement bedroom addition with framing, insulation, drywall, flooring, electrical and one egress window is $15,000 to $30,000 in the same guide, and an adjoining bathroom is priced on top.
Digging the well is exterior work, so season matters. HomeStars advises spring or fall for window wells and foundation waterproofing, and winter for the inside work. A fall request can fit both. See winter renovation for how Ottawa winters change the schedule.
Alarms, radon and the permit
The Fire Code update that took effect on January 1, 2026 asks for carbon-monoxide alarms on each storey where a home has fuel-burning appliances or an attached garage.
Health Canada’s radon guide lists a basement bedroom among the rooms to test. The long test it wants runs 91 days or more through the heating season, and the action line is an annual average above 200 Bq/m³. Put the result in the request.
The City requires a building permit for altering a building over 10 square metres; the permit page gives no separate rule for a bedroom. The renovation fee is $12.75 per $1,000, minimum $117. Whole-project numbers are on the basement renovation cost guide.
Beyond one bedroom
Two bedrooms, a kitchen and a separate door make the space a rental unit, and then the rules change. The secondary suite page covers that, and the basement bathroom page covers the room next to it.
Who digs the well
The Desk routes an egress request to one independent renovation company. That company measures the wall and the grade outside, then writes the quote and handles the permit under its own contract.
Questions to ask the company
- Is the window size in the quote the clear opening when the sash is open, or the frame size?
- What happens at the foundation: who engineers the opening, and how is the wall above it supported?
- How deep is the window well, and what climbs out of it if it passes 1000 mm?
- Is the bedroom wall insulated and finished in this quote, or only the window?
- Which City inspections cover the window, and who books them?
Have this ready for the call
- Photos of the outside wall where the window might go, showing the grade, the lawn and any deck, step or air conditioner nearby
- Foundation type if you know it: poured concrete, block or older stone
- How far the ground rises above the basement floor on that wall
- A radon test result, if you have one
Questions people ask
What size does an egress window have to be in Ottawa?
The City’s advisory, issued under the 2024 Ontario Building Code, asks for an unobstructed opening of at least 0.35 m² with no dimension under 380 mm when fully open. The window opens from inside without tools and holds itself open. On a sliding window the opening is measured on the part that actually opens.
Do I need a window in every basement bedroom?
Each bedroom that falls under article 9.9.10.1 needs a window that meets the egress rule. For a second unit, Ontario’s page also lists bedroom glazing of 2.5% of the floor area. Whether your plan has exceptions is a question for the building official or the company’s drawings.
Can a window well freeze or fill with snow?
It can, and then the exit is blocked. Drainage at the bottom, a cover that opens from inside and snow clearing all matter in Ottawa. HomeStars notes that window well and foundation work is weather-dependent and suits spring or fall, so ask the company how the well is drained.
Is a window limiter allowed on a basement egress window?
The City’s advisory says a window with a sill under 900 mm needs a limiter that can be bypassed without tools. Between 900 mm and 1000 mm no limiter is required. Windows with a sill under 1800 mm above exterior grade are exempt from the guard and restrictor rule.
Does a basement bedroom need a carbon monoxide alarm?
Since January 1, 2026 Ontario’s Fire Code update asks for carbon-monoxide alarms on each storey of homes with fuel-burning appliances, or an attached garage. A fully electric home with no garage is exempt. Ask the company where the alarm goes in the new bedroom layout and whether it is wired in or battery-powered.