What's the difference between a bow and a bay window?

A bow uses four or more equal sections curved gently outward for a soft, flowing look. A bay uses three sections — a fixed centre with two side windows at sharper angles — for a bolder, more angular projection. A bow feels graceful and panoramic; a bay feels architectural and bold.

Do bow windows open for ventilation?

They can. A bow typically combines fixed and operable lites — usually casements among the fixed panes — so you get airflow while keeping the symmetrical curve.

Are bow windows energy-efficient?

They can be. Each section uses Trust Build's triple-pane glass unit — Cardinal IG, argon fill, dual Low-E, and Super Spacer® warm-edge spacer — and proper insulation of the curved seat board, head board, and framing is essential. Our crews handle that integration so the whole assembly performs.

Do bow windows need special structural support?

Yes. Because a bow projects beyond the wall across a wide span, it needs proper support and weatherproofed, insulated framing. Trust Build handles the full structural integration as part of the installation.

How many sections does a bow window have?

Most bow windows have four, five, or six equal sections. More sections create a wider, more pronounced curve. Trust Build sizes the bow to your opening and the look you want.

Can I get a rebate on bow windows?

ENERGY STAR® certified windows may qualify for the Home Renovation Savings™ program — up to $100 per rough opening, with a home energy assessment required before work begins. Our team will confirm how it applies to your home. Full details at homerenovationsavings.ca.

BOW WINDOWS · CURVED 4–6 SECTION DESIGN · ENERGY STAR® CERTIFIED

Bow Windows in Ontario

Four or more equal window sections joined in a gentle curve, sweeping outward to create an elegant, panoramic alcove. Designed, structurally integrated, and installed by Trust Build's own expert crews.

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What Is a Bow Window?

A smooth, sweeping curve of glass that projects outward from the wall

A bow window in Ontario is built from four or more equally sized window sections set at shallow angles, joining together to form a smooth, rounded curve that projects outward from the wall. Where a bay window makes a bold, angular statement with three sections, a bow creates a softer, flowing arc of glass — sweeping the view across a wide span and bathing the room in light from every angle. Some or all of the sections can be operable for ventilation.

How a Bow Window Is Built

Engineered as a curved assembly, installed as a system

A Trust Build bow window is assembled from:

Four to six equal sections — joined at shallow angles to form the curve, rather than the sharper angles of a bay.
A mix of fixed and operable lites — typically casements among fixed panes, so the bow ventilates while keeping its symmetry.
An insulated, curved seat and head board — finishing the projection and creating a rounded interior alcove.
Proper structural support — cable or bracket support with weatherproofed, insulated framing to carry the wider projection.

A bow spans more of the wall than a bay, so structural integration is critical. Trust Build is an installation-first company — we engineer the support, insulation, and weatherproofing so the curve stays true, sealed, and solid for the long term.

Why Bow Windows Suit Ontario Homes

Panoramic light, elegant space, and refined curb appeal

Panoramic light and view

The curved span pulls daylight in from multiple angles and wraps the view around the room.

An elegant, rounded alcove

The gentle arc creates a graceful interior nook — a natural spot for a window seat or reading corner.

Standout curb appeal

A bow's sweeping curve adds a refined, classic character to a facade.

Flexible ventilation

Operable sections within the curve let you air the room while keeping the symmetrical look.

Engineered For Ontario

Triple-Pane Glass Unit

Every section of a Trust Build bow window is available with our triple-pane glass unit — three panes of glass, two argon-filled chambers, a dual Low-E coating that manages heat in both directions, and a Super Spacer® warm-edge spacer that reduces heat loss at the glass edge. Built with Cardinal Glass insulated units, it keeps a wide, curved projection comfortable and efficient through Ontario winters. Double-pane is available where the exposure allows.

Triple-pane construction

Three panes of glass separated by two insulating chambers.

Argon gas fill

A denser-than-air insulator that slows heat transfer through the glass unit.

Dual Low-E coating

Reflects warmth back into your home in winter and deflects solar heat in summer.

Warm-edge spacer

Reduces the cold bridge at the window's perimeter, where condensation and heat loss begin.

Certified Performance

Tested Energy Performance (Component Windows)

A bow is an assembly, so its performance comes from its component windows. The certified triple-pane values below are for the windows a bow is typically built from — using NRCan / ENERGY STAR® metrics (ER, U-Value, SHGC).

Component (triple-pane)	ER	U-Value	SHGC
Fixed lites (CV-F)	47	0.85	0.44
Casement lites (CCS-L)	42	0.90	0.37

Values are derived from certified product testing and may vary by size, configuration, and glass package. Higher ER and lower U-Value indicate better energy performance.

Features

Built for Ontario, backed for life

Curved 4–6 section design

Equal lites joined in a smooth arc.

Mix of fixed and operable lites

Ventilation without breaking the symmetry.

Rounded interior alcove

Usable curved space for a seat or nook.

Triple-pane glass unit

Cardinal IG, argon-filled, dual Low-E, Super Spacer® warm-edge.

Full structural integration

Support, insulation, and weatherproofing handled by our crews.

Insulated, curved seat and head boards

A finished, energy-efficient projection.

Built for Ontario

Engineered to resist warping, cracking, and fading.

Where Bow Windows Work Best

A sweeping span of glass as the centrepiece of the room

Bow windows shine in larger rooms where a sweeping span of glass can become the centrepiece — living rooms, formal dining rooms, and primary bedrooms, where the curved alcove invites a window seat or sitting area. Their wide, rounded projection suits homes with traditional or refined architecture, and on a front elevation a bow adds a graceful, classic silhouette that sets the house apart.

Customization

Shape your bow to fit the room and the look

Shape your bow to fit the room and the look: choose the number of sections (four, five, or six), which lites are operable (casements among the fixed panes), and a range of exterior frame colours. Add grilles to suit a traditional style, finish the curved interior seat board to match your trim, and select specialty glass — tinted or low-iron — where you want it.

Rebates & Financing

Save more on your bow window upgrade

Home Renovation Savings™

ENERGY STAR® certified bow windows installed as part of an eligible upgrade may qualify for the Home Renovation Savings™ program — up to $100 per rough opening through the assessment stream, with a home energy assessment required before any work begins. The program sets eligibility and amounts; we'll explain how it applies to your home. Full details at homerenovationsavings.ca.

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FAQ

Frequently Asked Questions

A bow window is built from four or more equal window sections set at shallow angles to form a gentle, rounded curve that projects outward from the wall, creating a panoramic, elegant span of glass.

Project Gallery

See real Bow Windows we've installed across Ontario

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A sweeping curve of light for your home.

Get a free, no-obligation quote from Trust Build — ENERGY STAR® bow windows, full structural integration, expert installation by our own crews, and flexible financing.