Top-Hung Window Aluminium Profiles: Sections, Walls and Weights
A top-hung window is hinged along its upper edge and opens outward from the bottom, so it can stay open in light rain and suits schools, offices, high-rise flats and ribbon glazing. A typical top-hung series is built from about nine extruded aluminium sections: outer frames, transoms, vent and fixed sashes, cover plates and trims, with main walls of 1.6 – 2.0 mm. This guide lists what each profile does and gives indicative weights for one series. Metline supplies the aluminium profiles; window fabricators make and install the windows.
- Opening type
- Top-hung, outward opening
- Main walls
- 1.6 – 2.0 mm
- Section weights
- About 0.09 – 1.79 kg/m
- Alloy
- 6063-T5 / 6060-T66
How a top-hung window works
In a top-hung window the vent sash hangs from friction stays or hinges at the head and swings outward at the bottom. Because the opening faces downward, rain runs off the outside of the sash rather than into the room, and the window can be left ajar for ventilation.
Top-hung vents are often combined with large fixed lights in one frame, separated by a horizontal transom, which is why a top-hung profile series includes both opening and fixed sash sections. Friction stays hold the sash at any angle, and restrictors limit the opening for safety in upper floors. On tall windows a chain winder or electric actuator may open the vent, including for smoke ventilation.
Each manufacturer's series has its own section shapes, so the figures below are indicative values for one typical series with 2.0 mm main frames. Always work from the die drawings and system catalogue for the profiles you actually order.
Profiles in a typical top-hung series
| Profile | Function | Wall (mm) | Indicative weight (kg/m) |
|---|---|---|---|
| Outer frame, heavy | Main perimeter frame fixed to the wall opening; carries the vent and fixed lights | 2.0 | 1.718 |
| Transom (horizontal crossbar), heavy | Divides the frame between vent and fixed light; must resist wind load across the span | 2.0 | 1.787 |
| Outer frame, light | Lighter frame for smaller openings | 1.6 | 0.847 |
| Transom, light | Lighter crossbar for smaller spans | 1.6 | 0.747 |
| Vent sash | Opening sash frame that carries the glass and the friction stays | 1.6 | 0.612 |
| Fixed sash (type A) | Glazing frame for fixed lights | 1.6 | 0.652 |
| Fixed sash (type B) | Alternative fixed glazing frame | 1.6 | 0.541 |
| Cover plate | Snap-on cover that hides fixings and grooves | 1.0 | 0.088 |
| Window trim | Finishing trim between frame and wall | 1.0 | 0.138 |
Indicative weights for one series. Section weight scales almost directly with wall thickness, so the same shape at 2.0 mm weighs about 25 % more than at 1.6 mm.
Estimating profile weight for one window
Profiles are bought by weight. Multiply each cut length by the section weight and add an allowance for saw cuts and offcuts (commonly 5 – 10 %). Example: a 1000 × 1500 mm window with a top-hung vent above a fixed light, using the heavy frame and transom.
| Member | Length (m) | kg/m | kg |
|---|---|---|---|
| Outer frame (perimeter) | 5.0 | 1.718 | 8.59 |
| Transom | 1.0 | 1.787 | 1.79 |
| Vent sash (about 0.95 × 0.55 m) | 3.0 | 0.612 | 1.84 |
| Fixed sash (about 0.95 × 0.85 m) | 3.6 | 0.652 | 2.35 |
| Total before allowance | 14.57 |
Illustrative calculation from the indicative weights above; real cutting lists include beads, covers and cleats and depend on the series.
Alloy, temper, tolerance and finish
| Item | Typical specification | Why |
|---|---|---|
| Alloy | 6063 or 6060 (EN AW-6063 / EN AW-6060) | Extrudes thin, complex sections with a smooth surface for coating |
| Temper | T5 or T6 (T66 for 6060 in Europe) | Strength for frames and transoms with good surface quality |
| Tolerances | EN 12020-2 or EN 755-9; ANSI H35.2 in the US | Friction stays, gaskets and covers only fit on accurate sections |
| Powder coating | Polyester powder, typically 60 – 80 µm, to Qualicoat or AAMA 2603/2604/2605 | Colour and weather resistance |
| Anodising | 15 – 25 µm, to Qualanod or AAMA 611 | Metallic finish and abrasion resistance |
Top-hung vents put the sash weight onto the friction stays and their screw fixings, so wall thickness at the stay grooves matters for screw pull-out. Heavier 2.0 mm frames and transoms suit larger openings, commercial buildings and higher wind zones; the 1.6 mm sections suit smaller residential windows. Non-thermally-broken series conduct heat; where energy codes set U-value limits, choose a thermal-break series. See the aluminium window profile guide for background.
Performance points to check
- Weather tightness: windows are classified for air permeability, watertightness and wind resistance under EN 12207, EN 12208 and EN 12210 (product standard EN 14351-1), or AAMA/WDMA/CSA 101/I.S.2/A440 in North America.
- Transom stiffness: the transom spans the full width and carries wind load from both lights; check deflection for the window width and wind zone.
- Stay sizing: friction stays are rated by sash weight and height; heavy insulated glass may need stronger stays or hinges.
- Safety: restrictors and cleaning positions are required in many markets for upper-floor windows.
- Drainage: frame and sash sections need drainage paths so water that passes the outer seal drains to the outside.
References and standards
- EN 14351-1 – Windows and doors: product standard, performance characteristics
- EN 12020-2 – Extruded precision profiles in alloys EN AW-6060 and EN AW-6063: tolerances
- EN 755-9 – Extruded rod/bar, tube and profiles: tolerances on dimensions and form
- AAMA/WDMA/CSA 101/I.S.2/A440 – North American Fenestration Standard
- Qualicoat – Specifications for a quality label for coatings on aluminium for architectural applications
Top-hung window aluminium (aluminum) profiles: FAQ
What is the difference between a top-hung and an awning window?
They are essentially the same opening type: hinged at the top and opening outward at the bottom. "Top-hung" is the common term in the UK, Europe and Asia; "awning" is more common in North America.
Why do the frame and transom have 2.0 mm walls while the sash has 1.6 mm?
The frame and transom carry wind load across the full opening and anchor the window to the building, while the vent sash spans a smaller area. Heavier walls also give better screw pull-out for stays and fixings.
Which alloy is used for top-hung window profiles?
6063 is standard worldwide and 6060 is common in Europe, usually in T5 or T6 (T66) temper, because they extrude thin, accurate sections with a surface that coats well.
How much aluminium does one top-hung window use?
A 1000 × 1500 mm window with a vent and fixed light in this example uses about 14.6 kg of profile before beads, covers and offcut allowance.
Does Metline make complete windows?
No. Metline supplies extruded and finished aluminium profiles to window fabricators and system companies, who cut, assemble, glaze and install the windows.
Need profiles for a top-hung window series?
Send your die drawings or section list, wall thickness, finish, quantities and destination. We will reply with availability and a delivered price.
