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Heritage System

The Heritage System is a solid metal casement providing the traditional look of putty glazed casements. It is most suited to heritage properties, where fine sightlines and aesthetics are a consideration. The frame incorporates double weather seals and will accept single glazing or up to 16mm double glazed units, providing much improved energy and weather performance over traditional alternatives. Our most suitable system for achieving curved or shaped casements to your specification.

System Features

Slim Frame Profile
Single Glazing
Double Glazing (12mm - 16mm)
Historic/Period Buildings
Tight Radius Curved Windows
Side Hung Unit
Top Hung Unit
Fixed Unit
Double Weather Seal
Rebated Leg Profile
Equal Leg Profile
Vertical and/or Horizontal Transoms
Silicone fine pointed glazing
Traditional Leaded Lights
Mock Leaded Lights
Optional Trickle Ventilation

System Drawing

Click images to enlarge

Opening Frame

Fixed Frame

Equal Leg Fixed Frame

Strength, Wind, Water And Security

The tests below are carried out on side-hung outward opening windows measuring 1645mm x 600mm and are tested excluding any additional security features.

BS 6375 Part 1: 1989 (exposure categories measured in pascals)

Wind 2000 Pa
Water 200 Pa
Air 600 Pa
Exposure Category 2000 Special

BS 6375 Part 2: 1987

Operational and strength characteristics PASS

BS 7950: 1997

Enhanced security performance PASS

Recommended Design Limits

Side Hung Casement

Max O/a Width 650mm
Min O/A Width 200mm
Max O/A Height 1700mm

Area of side hung casement must not exceed 1.105m2.
Casements over 1100mm high will require 2 handles.
Where width is greater than height, casement sash must be top hung.

Top Hung Casement

Max O/a Width 1200mm
Min O/A Width 300mm
Max O/A Height 500mm
Min O/A Height 300mm

Fixed Lights

Max O/A Width 1200mm
Max O/A Height 2400mm

The inclusion of glazing bars, trickle ventilation, opaque glazing and abutment details may alter performance data and design limits. Please contact our sales team to discuss any requirements outside of the standard size limits detailed above.


U-value performance based on an 16mm double glazed unit made up of 4mm float/8mm 90% Krypton filled cavity/4mm Planitherm total + with warm edge spacers.

Fixed casement overall value 1.7W/m2K
Opening casement overall value 1.9W/m2K
Centre pane value 1.2W/m2K

When incorporting a genuine Georgian bar add 0.4 to the U-value.

U-values calcuated in accordance with BS EN iso 10077-1:2006 based upon a single fixed light sample 1230mm x 1480mm and a single opening light sample 1230mm x 1480mm. Inclusion of glaze bars, trickle ventilation or equal leg will affect performance. Worst case system value 2.7W/m2K based upon single opening equal leg casement 1230mm x 1480mm with glaze bar and trickle ventilation.

Information from Heritage System Data Sheet

Version: BR-IS25 RevE

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