What a Basement Egress Window Costs in North Vancouver

The size the code actually requires

BC Building Code Article 9.9.10.1 sets the rule for a bedroom in a secondary suite. Except where the suite is sprinklered, each bedroom needs at least one window or exterior door openable from the inside without keys, tools, or removing a sash or screen. The window has to provide an unobstructed opening of not less than 0.35 square metres, with no single dimension smaller than 380 millimetres, and it has to hold that opening open on its own, without a prop.

Read that measurement the way an inspector reads it. It is not the size of the window frame on the wall. It is the actual clear space a body can pass through once the sash is open, the screen is out of the way, and any hardware is clear. A window that measures 900 by 600 millimetres on the frame can still fail if the operating sash only opens to a smaller clear area, which is common on older awning-style units that hinge from the top and swing out only partway.

Do the arithmetic before you assume an existing window is close enough. A round number helps: 0.35 square metres is roughly the area of a rectangle 610 millimetres wide by 575 millimetres tall, but the code does not accept a wide, short window that meets the area and misses the 380 millimetre minimum on the short side. Both tests have to pass, area and minimum dimension, at the same time.

Sill height and why some jobs need underpinning

The egress opening also has a maximum height off the finished floor, so a person can actually reach it. Where the window is the escape route for a room, the code expects the bottom of the clear opening to sit within reach of someone standing on the floor, generally no higher than about 1 metre above finished floor level in the acceptable solutions most North Shore inspectors apply. On a basement with an 8-inch concrete curb or a raised slab, that can mean the window has to sit lower in the wall than the existing opening does, not just wider.

This is where a straightforward window swap turns into a bigger job. If the sill of a compliant-sized window would sit below the top of the footing, the foundation contractor has to lower part of the wall, which is underpinning: excavating below the existing footing in stages and pouring new concrete to extend the wall down before the new opening is cut. Underpinning a single window opening adds real cost and time to what looked like a one-day window swap on paper.

This is also why we walk the basement with a tape measure before quoting a suite conversion rather than pricing from a floor plan. Two houses on the same street, built by the same builder in 1974, can have foundations poured to slightly different heights, and one needs underpinning while the other does not.

Cutting the opening

Concrete foundation walls on North Shore houses from this era typically run 200 to 250 millimetres thick. Cutting a new or enlarged opening means a concrete saw scoring the perimeter of the new opening, then a core drill or hydraulic breaker removing the section inside the cuts. Where the wall carries load above the opening, a structural engineer specifies a new lintel, a steel or concrete beam set above the opening to carry the wall load around the new hole, before any concrete comes out.

Rebar inside the wall changes the job too. Older North Shore foundations are lightly reinforced by modern standards, but cutting through any reinforcing steel needs a plan for how the opening still performs structurally once the bar is severed. This is one of the reasons DIY egress cutting is a bad idea on a load-bearing basement wall: cut the wrong bar and the wall above it can crack.

Dust and vibration control matter on an occupied lot. Wet-cutting keeps concrete dust down, and North Shore municipalities that require a demolition or building permit for foundation cutting also expect erosion and sediment control on site, since the slurry from wet-cutting concrete cannot legally wash into a storm drain.

The window well: clearance and drainage

Article 9.9.10.1 also covers what happens once the window opens into a below-grade space rather than open air. Where the required window opens into a window well, the code sets a clearance of not less than 760 millimetres in front of the window, measured from the glass to the inside face of the well. That is room enough for a person to stand and climb out, not just push the sash open.

A window well is a structural box, usually corrugated galvanized steel, precast concrete, or poured concrete, set into the excavation against the foundation wall. It needs its own drainage, because a well that fills with rain becomes a bathtub against your basement wall rather than an escape route. On the North Shore, where fall and winter rainfall is heavy, the well drain is typically tied into the perimeter drain tile at the base of the footing, with a layer of drain rock underneath the well floor so water moves down and away instead of pooling.

A well deeper than about 44 inches from grade to the window sill generally needs a permanently fixed ladder or steps built into it, so a person can climb out without help. That is a detail worth confirming with your specific municipality's building department before the well is ordered, since the trigger height and the acceptable ladder design are inspected against local practice.

Where an existing window sometimes still passes

Not every basement window needs cutting. Some 1970s and 1980s North Shore houses were built with larger basement windows than the code minimum, particularly walk-out lots where part of the basement sits at or above grade on one side. Measure before assuming. We have gone into homes expecting to quote four new openings and found two of the existing windows already clear the 0.35 square metre and 380 millimetre tests once the actual operating clearance is measured rather than the frame.

A window that is close but slightly undersized sometimes has a cheaper fix than a full re-cut: swapping the operating sash type. A slider that opens to only half its frame width can sometimes be replaced with a casement or awning unit in the same rough opening that opens to a larger clear area, without touching the concrete at all. That is worth pricing before assuming every window in the suite needs foundation work.

How this fits into a suite conversion budget

Egress is rarely the only line item driving a basement suite budget, but it is the one most likely to be missing from an early estimate, because it is invisible until someone measures. A two-bedroom suite conversion with two windows needing enlargement, one of them requiring underpinning, adds $13,000 to $20,000 to a project that a homeowner may have budgeted for as a finishing job.

This is also permit-triggering work in every North Shore municipality. Cutting a new opening in a foundation wall is structural work, so it needs a building permit and a structural engineer's sign-off on the lintel and, where relevant, the underpinning design. A like-for-like window replacement in an existing opening of the same size generally does not need the same level of review, which is the distinction worth confirming with your municipality before assuming a permit is or is not required.

We scope every proposed bedroom window with a tape measure at the first site visit on a suite conversion, specifically because this line item moves budgets more than almost any other single item in a basement scope.