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Windows and sashes

The composition of joinery is more complex than it seems! Find your way around the technical vocabulary

18/11/2025

Are you thinking of installing new windows or renovating your existing joinery? Understanding the different components of a window will help you better dialogue with your craftsman, compare quotes and make informed choices. Here's an illustrated guide to the elements that make up an aluminum window.

Vue intérieure d'un salon baigné de lumière

The main elements of a window: structure and opening

1. Fixed frame

(or “casing”) Frame, attached to the brickwork, on which a window light or door leaf is fitted.

2. Openning frame / Casement / Leaf

This is the moving part of the window, the one you open. A window can have one or two sashes, depending on the type of opening.

3. Hinges

Hinges are the hinges that allow the sash to rotate. They provide the link between the sash and the frame.

4. Locking System

Cremona is the locking system operated by the handle. It allows the window to be closed at several points.

5. Lever Handle

Located at hand height, the handle is the ergonomic element that opens or locks the sash.

Schéma décrivant les composants d'une fenêtre

Technical and finishing components

6. Glazing bead

The glazing bead is the profile that holds the glazing in place in the sash. It can be removed to replace broken glazing.

7. Transom

The transom is a horizontal part of the frame or an intermediate element that structures the window.

8. Upright

This is the vertical part of the frame, or a vertical element that divides the opening into several zones.

9. Central  stile/ mullion

Present on two-pane windows, the central mullion is a fixed or movable piece that separates the two sashes.

10. Transom Window

This is the fixed part above a window, often glazed, to let light through.

11. Exhaust grille

Placed in the sash, this grille allows air renewal while keeping the window closed, improving indoor air quality.

Un technicien entretien une fenêtre Installux de couleur grise.

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Decorative and safety features

12. Crossbars

Crossbars are decorative elements, fitted on the glazing or integrated into the interior. They recall the traditional style of small-paned windows.

13. Striker plate

The striker plate is a metal part fixed to the frame. It receives the locking points of the locking system and contributes to the security of the closure.

Each component of an aluminum window has a precise role, whether functional, aesthetic or technical. Knowing these elements allows you to better understand your estimate, ask your joiner the right questions, and choose the solution best suited to your needs.

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