What opening size does the Ontario code set for a basement bedroom window?

The code asks for a clear opening large enough to climb through, at a set minimum size, openable from inside without tools. The 2024 code now applies, so have the pro or the City confirm the wording. It's measured with the sash fully open.

Who in Markham approves a bigger basement window opening?

Building Standards, through a building permit applied for online. A same-size swap needs none, but cutting a foundation wall alters a structural wall. In a heritage district, exterior changes also need a heritage permit.

Can my existing basement window become an egress window without cutting concrete?

Sometimes. If the opening is big enough, a casement can reach the required clear opening where the old slider couldn't. If not, it has to be cut. A photo with a tape measure across the frame tells the pro which case you're in.

Why does my window well hold water after a storm?

Usually because it can't drain. A well should sit on gravel connected to the weeping tile or a drain, with ground sloping away, and older drains clog with silt. Clear it and have the drain checked before blaming the window.

If nobody sleeps in the basement, does the window need to be egress size?

The egress rule is written for bedrooms, so a rec room or office can keep ordinary windows. If a bedroom might come later, sizing a new window now can save cutting the opening twice.

Basement windows

Basement windows big enough to get out of

Most basement windows in Markham homes were sized for light and air, not for climbing through. Once the basement gets a bedroom, the code expects a window someone can use as a way out, and a small slider near the ceiling rarely qualifies. Sometimes a different window fits the opening; sometimes the foundation is cut. We connect you with an independent local installer who does basement windows, and the pro confirms which route suits your wall.

The code in plain words
Permit route explained up front
Same-size swaps quoted too

Get a free quote 905-201-8120

A casement opens fully onto a well with a ladder.

The rule

What makes a window an egress window

A bedroom needs a window that opens from inside without keys or tools and gives a clear opening big enough to climb out through, at the minimum size the Building Code sets, unless the room has a door straight outside. Those figures are from the 2012 code text; the 2024 Ontario Building Code now applies, so confirm the current wording for your project.

What counts is the clear opening with the sash fully open, so style matters:

Casement

Clears most of its frame, so it needs the smallest opening. See casement windows.

Slider

Only half opens, so it needs a much wider frame.

Awning

The sash and arms stay in the opening, so a basement awning is rarely egress on its own. Our awning page explains where they do fit.

Permits

Enlarging an opening: permits in Markham

Replacing a window in a same-size opening needs no City building permit. Cutting the foundation to make it bigger is different: the City's building permit page lists altering a structural wall, and adding a basement entrance, among the projects that need one. Applications go to Building Standards through the City's online ePLAN system.

An enlargement usually means cutting the concrete, supporting the wall over the new opening, setting the window and building a well outside. Ask the pro whether they prepare the permit drawings or work from yours, and whether the cutting is theirs or a foundation contractor's.

Second units

Second units and basement bedrooms

If the basement is becoming a separate unit, the window is one line in a larger permit. The City's guide to building permits asks for construction details of egress windows with those applications. Whoever draws the plans usually sets the window size; the installer builds to it.

A bedroom for your own family, with no second unit, still needs an egress window, and cutting a bigger opening still needs a permit.

Outside the wall

Window wells and drainage

A well gives room to climb out and keeps water off the glass.

Room to get out

The code sets a clearance in front of the window, and a deep well may need a ladder.

Somewhere for water to go

A gravel base tied to the weeping tile or a drain stops water pooling against the window.

A cover, if it suits

A clear cover keeps out snow and leaves but should push open easily from below.

Same-size swaps

Replacing basement windows the same size

If nobody sleeps there, a drafty or fogged basement window can be replaced in the same opening with no permit, and an old slider can become a tighter-sealing casement or a hopper that tilts in at the top.

If only the glass has fogged, a new sealed unit may be enough. Our replacement windows page explains when the whole window is worth changing, and the windows overview covers other types.

What affects the quote

What sets the scope of an egress job

The quote depends on:

Same-size opening, or cut larger
Wall type: poured concrete, block or framed
Window style and size to reach the clear opening
The well: digging, drainage, ladder and cover
Permit drawings, and who prepares them
Interior finishing around the new opening

Tell the pro which room it is, what the wall is made of and whether anyone will sleep there.

Get an egress window quote

Free to request. Quotes come in writing.

Questions

Basement and egress window questions

Explore your options

Local installers take on basement windows across Markham, including Milliken Mills, Thornhill, Box Grove and Berczy Village.

Tell us the room and the wall

Say which room it is, whether someone will sleep there and whether the wall is concrete, block or framed; a photo helps. We pass it to a local installer who does basement windows and gets back to you to measure and quote in writing.