Innovation and aesthetics united in a single system. KC51 Casement window mixes a modern and contemporary appearance with optimal technical features, especially its safety and energy saving benefits.

  • PAS 24 tested
  • Top and side hung applications
  • Ultra-slim sight lines
  • 24 mm polyamides
  • 4 to 33 mm glass options available
  • Joined using mechanical corner cleats
  • 75 mm polyamide sub frame section, for easy to install modular windows
  • Egress options as standard
  • Cills, add ons, curtain walling insert and coupler sections available
  • Reverse adaptors for interior/exterior glazing
  • Available as wide opening ‘escape’ windows
  • Compatible with exlabesa KLW curtain wall system
Technical information
Air permeability* Class 4
Water tightness* Class E1050
Wind load* Class B5
Thermal insulation Uw** Up to 1,5 W/m2K


* Air/Water/Wind tests according to standards BS 6375-12009, BS6375-2 & BS6375-3

** Please note: U-Values are dependant on size and glass U-Values.

Maximun size (top hung): 1500x1500 mm

Maximun size (side hung): 900x1500 mm

Maximum weight: 50 kg

Maximun glazing: 32,8 mm

Polyamide: 24 mm

Weather tested to BS6375-12009, BS6375-2 and BS6375-3 

PAS 24 Security 


KC51 casement window is a versatile system which offers a wide range of design options thanks to its flush, chamfered or sculptured internally beaded sash sections coupled with its complete range of 75 mm subframe which offers endless design possibilities and makes this system appropriate for residential and commercial applications.


This system has a glazing range from 4 to 32,8 mm offering a wide choice of glazing options. In addition, the HOi version introduces foam strips to further improve thermal efficiency for higher specification projects.


KC51 window system offers high thermal efficiency giving a Uw value of 1,5 W/m2K. Furthermore, the window has been tested in accordance with BS6375-1 2009 for Air, Water and Wind resistance making it an ideal choice for exposed or remote sites.


This system was designed taking into account security as the main factor. The 51 mm casement window system can be constructed as internally or externally beaded with a rebate adaptor profile compatible with both opening and fixed lights.

Technical manual

Register in our digital space Exlabesa 360 to have TechDocs at your disposal: a complete documentary library with all the technical information about Exlabesa Architecture’s aluminium systems.

Access Exlabesa 360 and enjoy exclusive content and functionalities:

  • Catalogues, tests, reports, sections, DAP, BIM objects…
  • Up to date information
  • Notifications of updates and news