Double Glazed Sash Upgrades

When installing double glazing to sash windows, the two main methods are to adapt your existing sashes to accommodate or manufacture them new, specifically designed to hold double glazing. Usually, the window case (box lining/surround) will still be serviceable and can be retained and refurbished.

We manufacture and install new sashes, pre-installed with double glazing as an economical and durable option. Our “Double-Glazed Upgrades” are designed to suit specified unit depths and sightlines and will be a custom fit to your existing window box. The design strikes a balance between historical detail and maximum energy efficiency. Visually, our new sashes are indistinguishable from the originals.

There is no need to remove panels or shutters during installation, meaning this method is pretty non-invasive from a structural standpoint. We install draught-proofing as standard when undertaking this work.

Double Glazing Sash and Case Windows

Integrated Glass Units (IGU's)

We manufacture double glazed units (IGU’s) at our Sighthill workshop to any required height and width with thicknesses ranging from 14mm to 18mm. The requirements and specification for each window depend on factors such as frame depth/thickness, astragal size and whether the property is located in a conservation area or is a listed building.

Unit measurements are usually shown in the format (4/8/4), which means: 4mm glass/8mm spacer bar/4mm glass.

14mm (4/6/4) is typically the maximum unit depth for a listed building. Units of more than 18mm depth can start to impact the traditional look of the windows. Units are normally made with one side of low e glass and the gap filled with Argon gas, depending on energy and cost requirements.

Vaccum glazing can also be installed in historic buildings and is an increasingly popular option due to its higher performance and lifespan over conventional units.

Double Glazing Into Existing Sashes

Fitting double glazing into existing sashes is a laborious undertaking, with the neatness of results depending greatly on the window frame’s underlying condition. On historic, multi-paned windows, the astragals (glazing bars) are usually very narrow and leave very little space for double glazing. We only undertake this kind of work in specific circumstances, such as council planning requirements, as in our experience new sashes leave a superior end result.

Upgrade to Fineo Vacuum units

Fineo double glazing offers the same thermal performance as triple glazing and significantly reduces noise compared to standard IGU’s.

The unit is only 8.5mm thick overall so is also suitable for retro-fitting when existing sashes have to be retained.

It exceeds current building regulations by offering an impressive u-value of 0.75.

It also comes with an industry leading 15 year warranty.

We are certified installers for the Fineo system.

Get a Double Glazing Upgrade Quote

Our team of specialist surveyors, carpenters and fitters are on hand to answer your questions and produce your custom quotation.