ST70 Concealed Sash

APA Facade Systems ST70 Concealed Sash window has a slim design, with a surface of only 66 mm from the exterior. The Slim profile provides the inside of the building with a substantial increase in luminosity.

A 35 mm thermally broken area, and the insertion of a polyamide core (ranging from 24 mm to 44 mm) in the frame and sash, allow it to reach values of up to 1.0 W/m²k of transmission, maximising its energy efficiency.

Acoustically this system has an increased level of sound insulation with the possibility of installing high-performance units of up to 40 mm.

The ST70 Concealed Sash meets all of the BS EN regulations demonstrating excellent water tightness, air permeability, and wind resistant values. With these features and it’s slim design, this window system is the ideal choice for apartments, houses or student accommodation.


  • Slim design with a surface of only 66mm from the exterior.
  • 35mm thermally broken area
  • Insertion of 24mm-44mm polyamide core
  • Values of up to 1.0W/m²k of transmission
  • A possibility of fitting 40mm high-performance units
  • Meets all BS EN standards

Frame Depth70mm
EN 12207:2000Air:Class 4
EN 12208:2000Water:E1650
EN 12210:2000Wind:Class C5
TransmittanceUw from 1,0 (W/m²K)
Acoustic Insulation Rw=46 dB