Double-hung and casement windows are two of the most common residential window styles installed in Canada. They look different, operate differently, and suit different situations. Choosing between them depends on factors including ventilation needs, the window's location in the home, and maintenance preferences.
How Double-Hung Windows Work
A double-hung window has two sashes — the upper and lower panels — both of which slide vertically within the frame. This is the most familiar window style in North American residential construction. The term "double-hung" distinguishes it from a single-hung window, where only the lower sash moves.
Most modern double-hung windows have tilt-in sashes that rotate inward to allow cleaning of both the interior and exterior glass surfaces from inside the home. This is a practical feature in multi-storey buildings where exterior access to windows is limited.
Ventilation in Double-Hung Windows
A double-hung window can be opened at both the top and bottom simultaneously. This creates a convective ventilation effect: cooler air enters through the lower opening while warm air exits through the upper opening. This airflow pattern can be effective for natural ventilation without a mechanical system, though the net opening area for each position is roughly half the window width.
How Casement Windows Work
Casement windows are hinged on one vertical side and swing outward (occasionally inward) when operated via a crank handle at the base of the frame. The sash opens like a door. Casements can be single (one sash) or paired.
Because the entire sash moves, a casement window can direct moving air into a room in a way that a vertically sliding window cannot. When angled to catch a prevailing wind, the sash acts as a scoop, increasing airflow into the interior.
Air Sealing in Casements
When closed and latched, casement windows compress their weatherstripping against the entire perimeter of the sash. This creates a tighter seal than double-hung windows, where the meeting rail between sashes is a common area for air infiltration. Casement windows typically achieve lower air leakage rates than double-hung windows of comparable quality.
Side-by-Side Comparison
| Feature | Double-Hung | Casement |
|---|---|---|
| Operating mechanism | Vertically sliding sashes | Cranked, hinged sash |
| Maximum ventilation opening | ~50% of window area | Up to ~90% of window area |
| Air infiltration (typical) | Moderate (sliding seals) | Low (compression seals) |
| Exterior clearance needed | None | Yes (outswing clears screen) |
| Glass cleaning | Tilt-in sashes from inside | Exterior accessible when open |
| Screen placement | Interior screen | Interior screen (outside of sash) |
| Common locations | Bedrooms, living areas, street-facing facades | Kitchens, above counters, side walls |
Practical Considerations by Room
Kitchens
Casement windows are frequently installed above kitchen sinks and counters because the crank handle can be operated from a distance, and the full-width opening provides more ventilation than a comparable double-hung. Reaching across a counter to lift a sliding sash is less convenient. However, the outswing of a casement requires that no obstruction (such as a deck railing or nearby structure) blocks the arc of the sash.
Bedrooms
Both styles are common in bedrooms. Some building codes in Canada specify minimum openable area for emergency egress from sleeping rooms; both double-hung and casement windows can meet these requirements, but the specific dimensions of the opening must be verified. The casement's larger openable area may make it easier to meet egress requirements in narrower window openings.
Street-Facing Facades
Double-hung windows are conventional on street-facing facades, particularly in traditional and transitional architectural styles common in Canadian suburban construction. They present a consistent visual pattern. Casement windows are also used on street facades, particularly in contemporary and craftsman-influenced designs.
Maintenance
Both window types require periodic inspection of weatherstripping and hardware. Casement windows have crank mechanisms and multi-point locking hardware that can require adjustment or replacement over time. The cranks are subject to wear and the arms that move the sash can corrode if not maintained in climates with road salt exposure.
Double-hung windows depend on balances (spring or block-and-tackle) to hold sashes at any open position. These can fail after many years, causing sashes to fall or not stay open. Replacement balances are generally available as parts from manufacturers.
Energy Performance
For a given frame material and glazing specification, casement windows typically have a slight advantage in U-factor and air leakage over double-hungs because of the compression seal. This difference is more meaningful in very cold climates. In practice, a well-manufactured double-hung with good weatherstripping performs comparably to a mid-range casement in most Canadian Zone 5–6 applications.