--- title: "Curtain Wall vs Window Wall: Slab Edge" description: "Curtain wall runs in front of the slab edge; window wall sits between slabs. That changes facade lines, details, and quotation scope." canonical: "https://afi.id/en/insight/curtain-wall-vs-window-wall" language: "en-US" last_updated: "2026-09-06T06:45:36.179Z" --- # Curtain Wall vs Window Wall: Slab Edge Curtain wall runs in front of the slab edge; window wall sits between slabs. That changes facade lines, details, and quotation scope. Source: https://afi.id/en/insight/curtain-wall-vs-window-wall Language: en-US Site: AFI ยท Alu Fasad Inovasi Part of: https://afi.id/en/insight **Date published**: 2026-08-25 ## These systems are distinguished by the slab edge. Curtain wall runs continuously in front of the floor-slab edge. Window wall fills the opening between two floor slabs, one level at a time. That changes the facade line, the joints, and the work that belongs in the quotation. ## Curtain wall and window wall in a building section Both systems use aluminium framing and glass. Read their position against the building structure before comparing anything else. - **Position at the floor slab**: Curtain wall sits outside the slab edge and runs across several storeys as one facade plane. Window wall sits between floor slabs, making each level a separate opening. - **The visible facade line**: Curtain wall gives the exterior a continuous reading from bottom to top. With window wall, the slab line becomes part of the facade rhythm and has to be resolved with its spandrel or slab-edge cover. - **Support and joints**: Curtain wall transfers self-weight and wind loads back to the structure through anchors at the slab edge. Window wall has to work as a storey-by-storey system, with its own head, sill, and slab interfaces resolved. - **Details that need coordination**: Water resistance, structural movement, glass, framing, and floor-to-floor separation still need resolving in both systems. The detail changes because the joint line and slab relationship change. - **Fabrication method is a separate choice**: Window wall describes where the facade sits on the building. Stick and unitized describe how a facade is divided, fabricated, and installed. One decision does not settle the other. ## The building section makes the choice Two elevations often look equally glazed and still call for different systems once the slab edge and floor layout are read. - Curtain wall is the choice when a design needs the facade plane to run continuously in front of the structure and work as one exterior skin. Window wall suits a repeated floor module where the system is meant to fill the opening from slab to slab. - Building height alone does not choose between them. Wind load, structural movement, opening arrangement, rain exposure, operable-window requirements, and interfaces with other systems all need checking in the working drawings. ## Compare price only after the facade line is the same Two square-metre rates do not describe the same work when one quotation puts the facade in front of the slab and the other puts it between slabs. - A drawing that only asks for full-height glass does not settle the system. The project team still has to decide the facade position, support details, water path, slab-edge cover, and responsibility at every interface. - Before comparing quotations, ask each party to show the building section behind its proposal. We read that section on your drawings first, because it is what makes clear whether the framing, anchors, glass, joints, installation access, and inter-floor details are genuinely comparable. - One building often uses both systems on different surfaces. The decision is not which name sounds better. Each surface and interface needs a detail that can be calculated, fabricated, and installed. ## Curtain wall and window wall questions The distinction disappears when the conversation stops at the glass. The building section shows the decision that matters. - **What is the difference between curtain wall and window wall?** Curtain wall sits in front of the floor-slab edge and runs across several storeys. Window wall is installed between floor slabs, so each facade module fills one level of the building. Both use the same aluminium and glass, but their structural details and joints differ. - **Is window wall the same as unitized curtain wall?** Not necessarily. Window wall describes the facade's relationship to the floor slab. Unitized describes how the facade is divided into panels and installed. Working drawings need to make both clear so the offered system is not the wrong one. - **Does a high-rise have to use curtain wall?** No system is chosen from storey count alone. Height, wind load, structural movement, slab layout, rain exposure, and facade form need to be considered together before the system is selected. - **Is curtain wall always more expensive than window wall?** The system name cannot answer that. A fair comparison includes facade position, framing, anchors, glass, inter-floor details, installation access, and responsibility for the joints. A square-metre rate becomes useful only once the scope is the same. - **Can one building use curtain wall and window wall?** Yes, when different building surfaces call for different systems. The transition needs clear detailing so the water path, movement, edge cover, and installation sequence do not become work missing from the quotation. ## Related reading - **Curtain wall for high-rise buildings** - **Unitized systems and panel installation** - **AFI's facade calculation and detailing capability** ## Start with the building section when choosing a facade system.