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Casement window

Hinged on the side, the sash swings outward with a crank handle and presses tightly against the frame seal when closed.

Casement window

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Pick a window or door type, drag or use ← / → to rotate the 3D model, and press the mechanism buttons to see how it opens.

How it opens and how it is built

The sash hangs on hinges along one side of the frame and swings outward on them. A crank handle on the sill turns a gear arm that pushes the sash open and pulls it back, and a lock pulls it against the weatherstripping all around the frame when it is closed.

The open sash stands out from the wall, so it needs clear space outside, and the outer glass is cleaned with the sash open. In the 3D model above you can check how the sash swings open.

Why you'd want it

A casement opens almost the whole sash, so it lets in more air than a hung or sliding window of the same size, and the open sash can catch a breeze that runs along the wall. Closed, it presses on its seal instead of sliding past it, and with no rail across the middle the view is clear.

An awning is hinged at the top instead and can stay open in light rain. A double-hung slides within the wall and needs no room outside, and a picture window gives the same clear glass without opening.

Pros and cons

Pros

  • Almost the whole sash opens, so the room airs quickly.
  • Closed, the sash presses against the weatherstripping all around, which keeps drafts out.
  • There is no rail across the middle of the glass, so the view is clear.

Cons

  • The open sash stands out from the wall and gets in the way of walkways, decks and bushes.
  • The crank and the hinges are moving parts that wear and may need adjustment.
  • A wide sash left open in strong wind puts a load on the hinges and the gear arm.

It's for you if…

  • The window is over a kitchen sink or a counter, where a crank is easier to reach than a sash to lift.
  • You want to catch the breeze in a room that gets stuffy in summer.
  • Nothing stands right outside the window: no walkway, deck or tall bushes.
  • You want a clear view without a rail across the middle of the glass.

Don't overpay if…

  • A walkway or a deck runs right outside the window: a double-hung or a sliding window opens without sticking out.
  • The window is only there for light or a view: a picture window costs less and has no crank or hinges.
  • You want to keep a window open in the rain, high on the wall: an awning does that better.

How it affects the price

A casement usually costs more than a single-hung or double-hung of the same size: the crank, the gear arm, the hinges and the lock are a more complex mechanism than a sash on balances. It is usually close to an awning, which uses the same kind of hardware, and costs more than a picture window.

Within the type the width of the sash, the size and the frame material move the price, and a wide opening is often split into two or more sashes, each with its own hardware.

All window types and their impact on the price →

Lifespan and care

Once or twice a year, clean the hinge tracks and the gear arm and lubricate them lightly as the maker advises, and check that the weatherstripping around the sash is whole. If the sash drags on the frame or does not close tight, the hinges need adjusting. Do not force the crank: if it gets hard to turn, clean the arm first.

Figures with sources

Where the hinges are
Casement windows have hinges on the sides of their sashesSource:Window Types — NFRC Consumer Guide to Windows (Efficient Windows Collaborative)
How the sash opens
open by swinging out or inSource:Window Types — NFRC Consumer Guide to Windows (Efficient Windows Collaborative)
Which family of opening windows it belongs to
the projected or hinged types such as casement, awning, and hopperSource:Types and Parts — NFRC Consumer Guide to Windows (Efficient Windows Collaborative)

What it pairs with

A casement works with any glass unit, and because the whole sash is glass, the glass unit and its Low-E coating decide much of how warm the window is. The frame material decides how stiff a wide sash stays, and the hardware — the crank, the hinges and the lock — how well it closes. How the window is set into the opening decides how well it seals.

Which glass unit to choose →How a window is installed →

Compared with similar types

Frequently asked questions

How does it work if bushes or a balcony are in the way outside?

The sash needs clear space to swing out, so bushes, a railing or a walkway right outside will stop it or get in the way. In such a spot a double-hung or a sliding window, which open within the wall, are the usual choice.

Are the crank and hinges stronger than the parts of a hung window?

It depends on the hardware and the size of the sash, not on the type alone. Look at what the estimate says about the crank, the hinges and the lock, and keep them clean so they last.

Is it a good choice for a windy spot?

Closed and locked, the sash presses against its seal, which helps against drafts. Open, a wide sash catches the wind, so in a very windy spot avoid leaving it wide open and ask for a sash size that suits the opening.

Can it serve as a bedroom escape window?

It often can, because most of the sash opens. The rules for bedroom escape windows depend on your local building code, so check them for your area and the size of the opening in the estimate.

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