The Sash weight is the weight of the moving part of the window – glass, frame and hardware together. Along with the installation position, it is the most important value for determining the required thrust force of a window actuator.
Rule of thumb for glass weight
Glass weighs about 2.5 kg per square metre and millimetre of glass thickness. Double glazing 4/16/4 has 8 mm of glass and therefore weighs about 20 kg/m², triple glazing 4/12/4/12/4 with 12 mm of glass about 30 kg/m².
Example
- Sash 1.2 m × 0.8 m = 0.96 m²
- Double glazing: 0.96 m² × 20 kg/m² ≈ 19 kg of glass
- plus frame and hardware (roughly 20–40 % depending on the profile): about 24–27 kg
Tip
It is better to calculate a little too heavy than too light. Find the right actuator with the Window actuator calculator.
Frequently asked questions
Do I have to weigh the sash?
No. An estimate based on glass area and glass make-up is usually sufficient. The glass make-up is often stamped on the spacer between the panes.
Why is the installation position so important?
With a rooflight dome or roof window, the actuator lifts almost the entire weight. With a tilt window in the façade, the hardware carries a large part and the actuator needs less force.
Read more
Not sure which actuator fits? Call us at 040 50694631 (Mon–Fri 8 am–5 pm) or use the actuator finder.
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Related terms: Mounting position · Chain actuator · Dome rooflight · thrust force
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