Optio 58BW ST steel replacement




Minimal, durable, secure.

The look of steel, the benefits of aluminium. A win-win for designers and homeowners alike. Featuring industry leading build quality, our 58BW ST aluminium windows are an ideal replacement for existing steel windows. In addition to impressive high thermal and acoustic performance, the design also replicates the minimal sight lines associated with steel windows, whilst providing superior performance and security. Yet another win-win.


Design features

  • Certified under the Secured By Design scheme
  • Tested to PAS 24
  • Green guide rated A
  • Integrated deep head profiles for ease of trickle ventilation
  • Unique polyamide thermal break design to improve thermal performance


  • 58mm or 70mm frame depth to accommodate varying types of applications
  • Internally or externally glazed
  • Glazing 25mm – 28mm**
  • Available for Lifetime Homes (LFT)
  • Available in a range of single or dual colour and anodised finishes
  • Available in the following aesthetics: Flush, Bay, Heritage and Contemporary
  • Available in the following configurations: top hung, bottom hung, side hung, fixed light, multilight and French casement

** Glazing thickness: Other thicknesses may be possible dependant on profile combinations specified. Fabricators should refer to AluK technical manual glazing section for details.

  Outward opening
U value W/m²K (Double glazing) : 1.4 W/m²K
U value W/m²K (Triple glazing) : 1.2 W/m²K
Window energy rating : A - B
BRE Green Guide rating : A Rated
Acoustic performance (dB) : Rw (C;Ctr) 43 (-2;-5) dB
Air tightness (Pa) : Class 4 (600 Pa)
Water tightness (Pa) : Class 9a (600 Pa)
Wind load (Pa) : Class E2400 (2400 Pa)
Security PAS 24 : X
Certifications : Q-mark
Secured by design : X
Opening : Open out
Top hung : X
Side hung : X
Bottom hung : X
Fixed Light : X
Multi light : X
french casement : X
Size limits
Top hung (max weight) : 35 Kg
Side hung (max weight) : 24 Kg
Bottom hung (max weight) : 60 Kg (3 hinges)
Fixed light (max weight) : 250 Kg
Frame depth : 58mm and 70mm
Dual color option : X
Multi-point locking : X
Glazing options : Internal and external
Glazing thickness : 25mm - 28mm**
Sightline (Frame to Vent) : 66mm
Sightline (Vent to Mullion) : 81mm
Sightline (Fixed Light) : 43mm
Bay : X
Contemporary : X
Heritage : X