Skip to content


Tel: 0208 893 4420
Fax: 0208 867 2767


Tel: 0800 043 1054
Fax: 0208 867 2767

Double Glazing Units for Listed Buildings

and Period and Conservation Area Properties

As specialists in slim double glazing for period, conservation and listed properties, we produce durable, high performance double-glazed units from as slim as 11mm.

As standard, our slimline glazing units include Softcoat 1.1 glass as its Low E pane, which is more thermally efficient than traditional hardcoated glass, such as K glass, and it also does not carry the same amount of colour.

Timbalite softcoated slimline double glazed units:

Unit ThicknessConfigurationCentre Pane UV W/m2KSightline (+1mm tolerance)
11mm4mm Softcoat 1.1 / 4mm Krypton filled cavity / 3mm Clear1.9 W/m2K7mm
12mm4mm Softcoat 1.1 / 4mm Krypton filled cavity / 4mm Clear1.9 W/m2K7mm
14mm4mm Softcoat 1.1 / 6mm Krypton filled cavity / 4mm Clear1.4 W/m2K8mm
16mm4mm Softcoat 1.1 / 8mm Krypton filled cavity / 4mm Clear1.2 W/m2K9-10mm
12mm4mm Softcoat 1.1 / 4mm Xenon filled cavity / 4mm Clear1.5 W/m2K7mm
14mm4mm Softcoat 1.1 / 6mm Xenon filled cavity / 4mm Clear1.2 W/m2K8mm

All centre pane U values are based upon calculations by Buildcheck Oracle (UKAS Certified)

Timbalite conservation glazing units are available with either a 4mm or 6mm cavity, with unit thickness from only 11mm and a perimeter seal width of from only 7mm. Some configurations can meet Part L for thermal efficiency when required for period properties.

This enables period property homeowners to benefit enormously from energy efficient, listed building double glazing, whilst replicating the original design of their period windows, including the narrow glazing bars so important to maintaining a truly authentic appearance.

Our thin double glazed units are available in a wide choice of glass types, including acoustic, laminated and reproduction Crown glass, which replicates the uneven reflection of original conservation or listed windows.

Example of conservation glazing detail:
12mm Timbalite slimline glazing unit

Sightline / Seal Depth:

11mm / 12mm unit with 4mm cavity: 7mm sightline (+1mm tolerance)
13mm / 14mm unit with 6mm cavity: 8mm sightline (+1mm tolerance)

These high performance conservation glazing units can be installed to both new and restored traditional listed windows and doors with timber beading or putty line detailing to match the existing.

We use the latest technology warm edge spacer bars in a choice of colours, ensuring they are as thermally efficient as possible and can produce centre pane U values of 1.9 or 1.5 Wm2K on a 4mm gas filled cavity, to as low as 1.4 or 1.2 Wm2K on a 6mm gas filled cavity, depending upon the type of gas fill used.

Timbalite slimline glazing units require:

  • minimum 8.5mm rebate depth
  • minimum 20mm rebate width

All Timbalite listed building double glazing units carry a 5 year guarantee and can be delivered nationwide in specialized packaging, ensuring they get to you in a perfect condition.

For more information or for our price list or installation guidelines, please call us on
0208 893 4420 or get in touch using our contact form.