Are you looking for the benefits of double glazing but don’t want to compromise on the aesthetics and slim proportions of a traditional sash window?
At HRG Services – The Timber Window Restoration Experts, we specialise in converting single pane, timber windows, into slim double glazed timber windows using our 12mm or 14mm slim double glazing units.
Our units are ultra slim, meaning that from a distance they still appear to be single glazed sash windows and therefore remain in keeping with your property’s traditional charm.
Once beaded or puttied in, our units still appear as single glazed glass – maintaining the period look while offering all the benefits of modern double glazing. Our units achieve a 1.9 U-value and, when combined with draught proofing, the improvements to thermal efficiency and noise reduction are instantly noticeable.
In addition to our slim double glazing packages, we also offer a Heritage Glazing Package — the perfect solution for complementing older properties and preserving the character of the existing glass.
Slim double glazing offers a discreet, energy-efficient solution for period homes, allowing you to enjoy the benefits of modern glazing without compromising the original character of your timber windows.
At HRG Services, we carefully install 12mm slimline units into your existing sash or casement frames – or offer the option to craft new sashes to fit your current boxes – depending on the condition and requirements of your windows.
These units maintain the traditional appearance from both inside and out, while improving insulation, reducing outside noise, and enhancing overall comfort.
Suitable for many listed buildings and conservation areas where approved, slim double glazing also helps reduce energy bills and can increase property value without changing the charm or character of your home.

HRG Services provides a bespoke heritage glass replacement service to suit our clients’ needs, throughout Dorset and the neighbouring counties of Hampshire, Somerset and Wiltshire.
On many of our projects, original glass is required to replace old or broken panes – something that can be expensive and difficult to source.
We use hand-blown cylinder glass sheets to replicate as closely as possible the original crown and cylinder glass used in the Georgian and Victorian eras from 1700 to 1860.
Thickness can vary within the same sheet, with an average of 3mm, and sizes also vary. The slight waviness and subtle imperfections help recreate the authenticity of historic glass, refracting light in a way only traditional glazing can.
Some traditional timber windows are already built with enough depth to accommodate slim double glazing units. In these cases, installation is straightforward and minimally invasive.
For windows that aren’t deep enough, HRG Services offers our specialist Route & Install Package. This service carefully adjusts the existing timber sash to create the precise rebate needed for retrofitting slimline double glazing, without compromising the integrity or appearance of the original window.
It’s the ideal solution for homeowners wanting improved thermal performance while retaining their period features.

Included in the Glass Replacement Package:
Our Glass Replacement Package is designed to restore the function and appearance of your original windows without unnecessary disruption. Whether you require heritage-style single glazing or slim double-glazed units, we’ll ensure a seamless result that’s in keeping with the character of your home. This service is ideal for addressing breakages, condensation issues, or upgrading to improved performance glass with minimal visual impact.
Included in the Slim Double Glazing Package:
The Slim Double Glazing Package is an ideal solution for homeowners seeking energy efficiency without altering the appearance of their original timber windows. Whether we retrofit new units into your existing sashes or craft accurate replacements, your windows will maintain their traditional aesthetic while benefiting from improved insulation and comfort. All work includes detailed finishing and paintwork to ensure a polished, lasting result.