Casement window height

The hard part about casement window height is not finding a standard number. It is realising that the standard number you find is written in a unit system that does not line up with the unit system your wall is built in. A casement window is a side-hinged sash that swings open like a door, and its height looks like a single figure on a brochure until you try to order it. This guide walks through the four different heights that all get called "the size", why published ranges disagree, what ALPES actually publishes for its outward-opening casement series, and how to turn a height into a purchase order that a factory can cut to.

The hard part is not the standard number, it is the metric one

One inch equals 25.4 millimetres. That is arithmetic. But when you convert the imperial heights that dominate North American catalogues, the result almost never lands on a round metric number, while metric catalogues themselves run on a 100 mm or 300 mm module grid. So the same window that is "48 inches tall" in one document becomes "1219.2 mm" in another, and the factory that extrudes on a 1200 mm module has to decide whether you meant 1200 or 1219. The two are not interchangeable when you are cutting a rough opening in concrete.

Notice the gap widens as the window grows. A 24 inch height is only about 10 mm off a round module; a 72 inch height is nearly 29 mm off. That is why a tall casement is where unit confusion turns into a cut that does not fit the wall.

Four numbers that all get called "height"

Before quoting anything, separate four figures that suppliers, builders and brochures all loosely call "the size". They are not the same measurement, and only one of them belongs on the purchase order.

The rule that saves rework: write the actual frame size in millimetres on the purchase order. The nominal label is for conversation, the rough opening is for the wall, and the net clear opening is for the building inspector. None of those three should be the number the factory cuts.

Published height ranges do not agree

If there were one global casement height, the catalogues would match. They do not. The figures below are third-party published ranges, not ALPES specifications, and they are shown only to prove the point that no single standard exists.

Because the ranges disagree, the only height that matters for your project is the one confirmed against your own wall and your chosen series. Treat any catalogue maximum as a starting point to question, not a promise.

What ALPES actually publishes for its casement series

ALPES builds three outward-opening casement series on the same 6060-T66 aluminium system with PA66GF25 multi-chamber thermal break. The published dimensions that matter for height planning are the frame wall width and the glass sash thickness, because those decide how the sash sits in the wall and how much glass it carries.

All three use ROTO, CMECH or Wehag hardware and open outward. The C116 carries a 34 to 44 mm multi-chamber insulation strip and the slimmest visible mullion at 22 mm. None of the three publishes a maximum sash height in the public catalogue, which leads straight to the next point.

Why the real limit is load, not a size chart

An outward casement sash hangs from its hinges, and the hinges are rated per sash, not per window. Glass weighs about 2.5 kg for every square metre of each millimetre of thickness. A tall sash with a heavy insulated glass build-up puts more weight on those hinges than a short one, so the tallest sash a series can hold is set by glass weight plus hinge rating, not by a line on a height chart. ALPES does not publish a maximum casement sash height for the C-series, and it should not be assumed. Request it together with your glass specification, because the answer changes the moment you choose thicker or laminated glass. CMECH hardware is tested to 30,000 cycles, which is a wear figure for the operator, not a height limit for the sash.

Wall depth is the number that decides fit

Frame wall width for the C-series runs 113 to 119 mm. That dimension must sit inside the wall cavity. A 2x4 stud wall is about 114 mm face to face, and a 2x6 wall about 165 mm. The C-series fits a 2x4 cavity with very little room for reveal adjustment, and it fits deeper walls comfortably. Frame depth is a property of the series, not something you add by choosing more tracks, so confirm the wall thickness before fixing the height, because a tall sash in a shallow wall leaves no room to true it up.

Standard or custom

A paste-ready millimetre order table

Use these as a starting grid, then confirm the maximum sash height for your glass with the factory. Every figure is the actual frame size in millimetres.

The full opening package

When the casement schedule is only part of a larger opening package, the same ALPES system can also quote the doors that share the facade. Specifiers coordinating a villa or apartment block can review commercial swing and bi-fold doors for the openings that do not suit a side-hung casement, match terraces with modern bi fold doors, and coordinate the main threshold with an entry door modern from the same supplier, which keeps the profile, colour and hardware families consistent across the project.

What to put in the RFQ

Frequently asked questions

• Does ALPES publish a maximum casement height? Not in the public catalogue. Request it with your glass build-up, because the limit is set by sash load.
• Should I order in inches or millimetres? Order the actual frame size in millimetres; convert imperial only as a check, never as the cutting number.
• Why does my 48 inch window not match 1200 mm? Because 48 inches is 1219.2 mm, which sits between metric modules. State the module you want.
• Which ALPES series is slimmest in the mullion? The C116, with a 22 mm visible mullion width.
• Does frame depth change with more tracks? No. Frame depth is a property of the series, not the number of tracks.
• Can a tall casement go in a 2x4 wall? The C-series frame wall width is 113 to 119 mm, close to a 2x4 cavity, so confirm reveal room before fixing height.

Short checklist before you order

• Write the actual frame size in mm on the purchase order, not the nominal label.
• Confirm the maximum sash height for your glass with the factory.
• Check frame wall width against your wall cavity.
• Pick a height on the 600 / 900 / 1200 / 1500 / 1800 mm grid unless you go custom.
• Keep the rough opening about 12 to 15 mm larger than the frame on each side.