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Glass Units
Glass Units
Glass Units

Help with Ordering your Double Glazed Units

Outer Pane

For most domestic properties this is typically 4mm Clear. For larger patio door units over 2 m2 it is advisable to order 6mm glass as large sheets of 4mm glass may bow during the toughening process.
6.8mm Laminate serves two purposes. It has very good acoustic properties helping to cut out noise and is also a safety glass helping to prevent break ins through the glazed area. The laminated glass will stay in place when smashed making it more difficult for would-be thieves to get in.
A selection of patterned glass is also available for any obscure bathroom or door units required, these will always be the outer pane. However, the unit can be reverse fitted so your patterned pane is on the inside of the property.


The overall thickness of the unit you require will determine the cavity thickness required. For example a 4mm Clear Outer / 16mm Spacer Bar - Cavity / 4mm Softcoat Inner would create an overall unit thickness of 24mm.
The cavity will always be filled with Argon gas as standard, it is this heavy inert gas along with the softcoat inner pane that makes the units high performance units.

Spacer Bar

This is the bar around the perimeter of the unit used to space the two panes of glass. This is available in Silver or Brown/Bronze Aluminium, Black, White, Gold or Grey warm edge. Warm Edge bars are made from a plastic material and reduce thermal transfer which improves the overall performance of the unit.

Inner Pane

For the Inner Pane 4mm Softcoat is the most common option for most domestic properties. The softcoat is a coating that is on the inside of the unit that helps to reflect the heat back into the property. All modern high performance sealed units should have a softcoat inner pane. 6mm glass should be selected for any units over 2 m2 or where a thicker, stronger glass is required.

Toughened/Safety Glass

Units which will be fitted into a window where the glazed area is low and falls within 800mm from finished floor height should be toughened. Units which will be fitted into a door or adjacent to a door should also be toughened. Toughened Glass is also referred to as saftey glass, once toughened the glass is much harder to break but also breaks into lots of tiny pieces which are less likely to injure than larger shards of glass.

Georgian bars

These are optional and mimic the bars used to separate smaller panes in older wooden windows. These are 18mm or 25mm wide and typically white or Wood Effect. Read more about Georgian Bars...

Duplex Bars

Also known as Back to Back or Grill, Duplex Bars divide a Double Glazed Unit to give the appearance of individual panels/units in Georgian and similar style properties. Astragal Bars are then placed onto the unit to finish the appearance.

Leaded Lights

We can supply leaded Units in various width of lead, Antique or Bright and in many formats specific to your requirements. We can work from photos and just a few simple measurements to ensure your Unit matches.

Cut Outs

Whether it's a Pet-flap or Venthole, we can create a Unit ready for installation of your flap. Please bear in mind that the cut out cannot be any closer than 70mm from the edge of the Unit.


Need a raked, arched or round Unit? No problem... Simply select the option of Single or Multi Cut shape. A single Cut Shape is simply a Unit that has, from a standard rectangle Unit, one single straight-line cut. Anything else is classed as a Multi Cut Shape.

Stepped Units

There are various reasons why you may need to order a stepped units. It may be for an uprise on a Skylight. In this case the outer pane is larger on all 4 edges than the inner. This overhangs the uprise and allows the water to run clear off the uprise structure. Another reason is for conservatory, on Lean too Glass roofs to again allow for water to run off, in this case usually into your gutter system and only stepped on one edge again on the outer pane. Stepped Units can also be used when, in an older property, achieving a Double-Glazed Unit replacing Single pane but do not have the rebate. In this case it is the inner pane that is large and Stepped on all 4 edges.

Size (Unit Dimensions)

Width x Height in millimetres. The units will be made with a +2mm/-1mm manufacturing tolerance, a tolerance should also be allowed for fitting, this tolerance will be determined by the specific rebate depth of your frame. It is important to input the width and height the correct way around for any patterned glass units as some of the patterns are directional. We advise allowing around 4/5mm 'wiggle' room on each edge of your unit. So, allowing a total of 8/10mm on both width and height.

Unit Thickness

The unit thickness can vary from window to window. The only sure way is to either measure with reach-around calipers or removal of the unit to measure. In cases where the unit thickness measures 0.5mm short of an even whole number (for instance 23.5mm) then round up to the nearest whole millimetre. So, in this case the unit thickness needed for order is 24mm.

How to measure your replacement sealed units

The most accurate way to measure your unit is to remove it from the frame.
This is a relatively simple process as seen in this video. How to remove a double glazed unit.
You can purchase a glass thickness and cavity depth Measuring Tool
Alternatively, you can measure the window in situe by removing a single bead to see how far the unit sits into the rebate. You can measure the overall thickness of the unit by opening one of the opening windows then measuring the thickness using reach around calipers.


A Ten year Guarantee applies to units glazed into UPVC and Aluminium frames.
A Five year Guarantee applies to all units filled with Krypton Gas
A Five year Guarantee applies to units glazed into wooden frames. When glazed into wooden frames it is understood that the frames must be maintained to ensure continued protection of the edge seal from water and sunlight penetration.
A Five year Guarantee applies to units fitted with edge tape.
The Company reserves the right to inspect any unit under claim on site.
The Guarantee is not transferable.
Any contract to which these conditions apply shall be construed and take effect in accordance with English Law which shall be the proper law of the contract.
All units should be inspected before glazing. The company will not accept for whatever reason responsibility for the deglazing and re-glazing of units deemed to be faulty after fitting.
Units will be inspected on-site in accordance with the Glass and Glazing Federation terms of reference for inspection of sealed units.