Etobicoke Split-Levels: Updating the 1960s Bay Window

Etobicoke's split-level neighbourhoods — Markland Wood, Eatonville, Richview, Princess Gardens, West Humber — were built in a wave from the late 1950s through the mid-1970s. The split-level design defined suburban Toronto in that era: a tri-level floor plan with the living room half a flight up, the family room half a flight down, and bedrooms on the top level.

And almost every one of them has a bay window in the living room.

That bay window was a selling feature in 1965. In 2026, it is the biggest source of heat loss in the house, the most likely place for wood rot, and the number one complaint from homeowners who have updated everything else.

Anatomy of a 1960s Bay Window

Understanding what you are replacing matters, because a bay window is not just glass — it is a structural assembly that projects from the wall plane.

The Components

• Head board: The horizontal header at the top of the bay, fastened to the wall framing above the window opening
• Seat board: The bottom shelf (the window seat). On 1960s bays, this is typically 3/4″ plywood over a 2×4 frame
• Support cables: Steel cables or rods running from the head board through the wall and anchored to the wall framing. These carry the weight of the bay assembly
• Side panels: Angled side windows (typically at 30° or 45°) flanking the centre panel
• Centre panel: Fixed picture window or operable casement
• Mullions: Vertical dividers between panels. On wood bays, these are solid wood with putty-glazed single panes

What Goes Wrong After 60 Years

1. Wood rot in the seat board. The plywood bottom is exposed to rain splash, snow melt, and condensation. After 40–60 years, it is soft, punky, or actively crumbling.
2. Rusted support cables. The steel cables corrode where they enter the wall — exactly at the point where water drips in. Weakened cables cause the bay to sag away from the house.
3. Single-pane glass. Original 1960s bay windows use single-pane glass with putty glazing. No Low-E coating, no gas fill, no thermal break. The U-factor on these windows is roughly 5.5 W/m²·K — five times worse than a modern triple-pane unit.
4. No insulation under the seat. The cavity beneath the seat board is either empty or packed with fiberglass batts that have compressed, gotten wet, and lost their insulating value. This cavity is exposed to outdoor air on three sides.
5. Air infiltration. Gaps at the wall junction, around the mullions, and through cracked putty create continuous air leakage. On a windy day, you can feel cold air pouring in around the seat.

A 1960s single-pane wood bay window loses as much heat as an open 2-square-foot hole in your wall. In a Toronto winter, that translates to $300–$500 in annual heating waste — just from one window.

The Replacement Options

Option 1: Full Vinyl Bay Window (Recommended)

A modern vinyl cantilevered bay window replaces the entire assembly — glass, frame, seat, and support structure.

What is included:

• Factory-built vinyl frame with welded corners
• Triple-pane IGU with Low-E coating and argon fill (ER 34+)
• Insulated seat board (rigid foam core)
• Steel support brackets or cantilevered framing
• Spray foam insulation in the cavity
• Aluminum exterior capping (maintenance-free)
• Interior drywall patching and trim

Cost: $3,500–$7,000 depending on width (typical Etobicoke split-level bays are 6–8 feet wide)

Pros:

• Complete thermal upgrade (R-5+ glass, R-20+ cavity)
• Zero wood to rot
• Maintenance-free vinyl and aluminum exterior
• ENERGY STAR certified
• Transforms curb appeal

Cons:

• Higher upfront cost
• 1–2 day installation (exterior work required)
• Requires removing interior trim and patching drywall

Option 2: Flat Window Conversion

Some homeowners decide they do not want a bay at all. Removing the bay projection and installing a flat picture window or casement combination simplifies the wall and eliminates the cavity insulation challenge.

Cost: $1,500–$3,000 for a flat window, plus $500–$1,500 for closing up and re-siding the exterior wall where the bay was.

Pros: Cheaper, simpler, better air seal

Cons: Loses the interior shelf, changes the exterior appearance, may require a building permit for structural changes

Option 3: Glass-Only Replacement (Not Recommended for 1960s Bays)

If the wood frame is still structurally sound (rare after 60 years), you could replace just the glass with new sealed IGUs and reglaze the wood mullions.

Cost: $800–$1,500

Why we don't recommend it: On most 1960s Etobicoke bays, the wood frame is compromised. Swapping glass into a rotting frame is a temporary fix that delays the inevitable replacement by 5–10 years while still leaving you with poor insulation and air leakage. For frames that are genuinely solid, glass-only replacement can work — but verify the wood condition first.

The Installation Process

Day 1: Removal and Prep

1. Interior protection: Drop cloths on floors and furniture. Remove curtains and window treatments.
2. Remove interior trim: Casing, stool (interior sill), and apron come off. Saved if in good condition for reuse.
3. Remove old bay assembly: The entire unit — glass, frame, seat board, support cables — is extracted as one piece. This is the messy part. Old caulking, insulation, and debris come out with it.
4. Inspect the rough opening: Check the header beam, jack studs, and sill plate for rot or structural damage. Reinforce if needed (add $300–$800 for structural work).
5. Flash and wrap: Install peel-and-stick membrane flashing around the opening to prevent future water infiltration. This is the single most important step for longevity.

Day 2: Installation

1. Set the new bay: The factory-built vinyl bay unit is lifted into position and fastened to the rough opening with structural screws through the head and seat.
2. Level and plumb: Shims ensure the bay sits perfectly level. An out-of-level bay will bind the operable side windows.
3. Insulate the cavity: Closed-cell spray foam is applied under the seat board and in the gaps between the bay frame and the rough opening. This provides R-20+ insulation and acts as an air and moisture barrier.
4. Exterior capping: Pre-bent aluminum cladding covers the head, seat, and side panels. Colour-matched to the vinyl frame. Sealed with high-quality polyurethane caulk.
5. Interior trim: New casing and stool installed. Drywall patched where the old trim was wider.

Why Spray Foam, Not Fibreglass

The cavity under a bay window seat is awkward — shallow, irregular, and exposed on three sides. Fibreglass batts:

• Compress when stuffed into tight spaces, losing R-value
• Absorb moisture and hold it against the plywood
• Leave gaps at corners and around cables/brackets

Closed-cell spray foam:

• Conforms to every irregular surface
• Provides R-6.5 per inch (vs. R-3.5 for fibreglass)
• Acts as its own vapour barrier
• Does not absorb moisture

Spray foam insulation in the bay cavity is the difference between a warm window seat and a cold shelf you never sit on.

Curb Appeal: Before and After

The visual transformation is dramatic. A 1960s wood bay with peeling paint, aluminum capping that is separating, and cloudy single-pane glass says "deferred maintenance." A new vinyl bay with clean lines, triple-pane clarity, and tight aluminum wrap says "this house is cared for."

For Etobicoke split-levels where the bay window dominates the front façade, this single upgrade has more curb appeal impact than a new front door, new siding, or landscaping. It is the first thing people see.

If the rest of the house also needs window attention, our residential window replacement service covers whole-house projects across Etobicoke and the GTA.

Frequently Asked Questions

How much does it cost to replace a bay window on a 1960s split-level in Etobicoke?

A full vinyl bay window replacement (including frame, insulated seat, spray foam, and exterior capping) runs $3,500–$7,000 depending on the width, number of panels, and whether the structural header needs reinforcement.

Can I replace my bay window with a flat window instead?

Yes, but it changes the exterior look significantly and may require a building permit if you are altering the structural opening. A flat picture window or casement combination is cheaper ($1,500–$3,000) but eliminates the interior shelf and the architectural character.

Why is the area under my bay window so cold?

The cavity beneath the bay window seat is typically uninsulated or packed with compressed fiberglass batts that have lost their R-value. This cavity is exposed to exterior air on three sides — essentially a box hanging outside your wall with only a thin plywood bottom. Spray foam insulation fills every gap and provides R-20+ in the cavity.

Do I need a building permit to replace a bay window in Etobicoke?

If you are replacing the bay window with the same size and configuration (like-for-like), no permit is typically required. If you are enlarging the opening, changing the window type, or altering the structural support, a permit is needed from the City of Toronto.

What holds up a bay window on a split-level?

Most 1960s bay windows are supported by steel cables anchored to the wall framing above, combined with a cantilevered seat board bracketed to the wall studs. Modern replacement bays use insulated steel support brackets or a full cantilevered frame system that is structurally self-supporting.

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