Heritage Unit Advantages


  • Heritage units comply with Building Regulations Document J in Scotland and Document L in England for improved thermal insulation.
  • The 5mm perimeter seal of heritage double glazed units enables them to be glazed into 7mm deep glazing rebates.
  • Smaller cavities between the glass panes reduces the required glazing width rebates and enables slimmer sections to be used.
  • The heritage unit is the only double glazed unit that can be glazed into most standard timber window astragals.
  • Heritage units can be glazed into most existing single glazing glass rebates.
  • Using heritage double glazed units offers savings in timber costs, installation, and the improved insulation will help protect the environment, through the lowering of carbon dioxide emissions, as well as savings on your fuel bills.


The Super Spacer is a pre-desiccated structural warm Spacer System which prevents a cold perimeter bridge caused by the aluminium in older type units.

The Super Spacer normally referred to as warm edge technology, has little or no effect on the centre of glass U value or insulation, often referred to in the specification of double glazed units.

Super Spacer incorporates a drying agent which absorbs any moisture present in the air or gas in the cavity between the glass. The structural foam nature of the extrusion also enables shaped units, particularly circular shapes to be manufactured, without the use of the bending processes necessary for aluminium spacers.

The construction of Heritage Double Glazed Units with Super Spacer ensures that there is no cold perimeter bridge and has little or no effect on the centre of pane U values or insulation properties of Heritage Double Glazed Units. However the perimeter insulation value can be affected by the perimeter conductivity of window frame materials particularly metal or aluminium. One of the best window frame materials with a very low thermal conductive rate is timber.

Super Spacer edge technology is now becoming more extensively used in the UK manufacture of Double Glazed Units and has the important effect of ensuring that there is no significant temperature differential from the centre to edge of the unit.