Double Glaze Existing Sash Windows

Why Installing Double Glazed Sash Windows Is A Better Option Than Single
Glazed Windows

At Mortice & Green, we specialise in helping homeowners double glaze existing sash windows without compromising the original character of their property. Since 1994, our family-run business has been restoring and upgrading traditional timber sash windows throughout London, combining expert craftsmanship with sympathetic restoration techniques. By retrofitting slimline double glazing into your existing timber frames, we can significantly improve thermal efficiency, reduce outside noise and enhance comfort while preserving the beautiful period features that make your home unique. Every project is completed by our experienced in-house restorative joiners, ensuring the highest standards of workmanship and customer care.

Improve Energy Efficiency Without Replacing Your Original Windows

Many homeowners believe that replacing their original sash windows is the only way to improve insulation, but in many cases this simply isn’t necessary.

Our specialist service allows us to double glaze existing sash windows by carefully installing slimline double glazed units into the original timber sashes wherever suitable. This approach preserves the appearance, proportions and craftsmanship of your original windows while delivering many of the benefits associated with modern glazing.

Retrofitting double glazing can help:

• Reduce heat loss throughout your home.
• Improve energy efficiency.
• Lower heating costs.
• Minimise external noise.
• Reduce condensation.
• Maintain the traditional appearance of your sash windows.

By upgrading your existing windows rather than replacing them, you retain the charm and value of your period property while enjoying a warmer, quieter and more comfortable home.

A Conservation-Friendly Solution for Period Properties

Double glazing existing sash windows is often an excellent solution for owners of Victorian, Georgian and Edwardian homes who want modern performance without losing their property’s historic character.

At Mortice & Green, we have extensive experience working on listed buildings and properties within conservation areas throughout London. Where planning requirements allow, we install slimline double glazing units that are specifically designed to maintain the original appearance of traditional timber sash windows.

Before any work begins, our experienced joiners carefully assess the condition of the existing windows to ensure they are suitable for upgrading. Where necessary, we can also carry out sash window repairs, timber restoration, sash cord replacement, draught proofing and complete refurbishment before installing the new glazing.

This comprehensive approach allows homeowners to maximise the lifespan of their original windows while significantly improving everyday performance and comfort.

Why Choose Mortice & Green to Double Glaze Existing Sash Windows?

Since 1994, Mortice & Green has built a reputation as one of London’s leading specialists in sash window restoration and refurbishment. Our experience allows us to sympathetically upgrade traditional timber windows while preserving the craftsmanship and architectural detail that make period properties so distinctive.

Every quotation is carried out by one of the company proprietors, and all work is completed exclusively by our own highly skilled restorative joiners. We never subcontract projects, enabling us to maintain complete quality control and consistently high standards across every installation.

Our philosophy is simple: preserve original windows wherever possible. Rather than recommending unnecessary replacements, we provide honest advice based on the condition of your existing windows and recommend the most appropriate long-term solution.

All repair work is backed by our minimum three-year guarantee, while any bespoke replacement hardwood sash windows we manufacture are covered by an industry-leading 25-year guarantee, giving you complete confidence in the quality of our workmanship.

Areas We Cover for Double Glazing Existing Sash Windows

We provide specialist double glazing for existing sash windows throughout London, helping homeowners improve the energy efficiency of their period properties while preserving their original timber windows.

Our team regularly carries out projects in:

• Kensington
• Chelsea
• Fulham
• Putney
• Wimbledon
• Hampstead
• Islington
• Hackney
• Notting Hill
• Mayfair
• Belgravia

We also cover properties throughout:

• North London
• South West London
• West London
• North West London
• Central London

If your property is located elsewhere in Greater London, please contact our team. We’ll be happy to confirm whether we cover your area and arrange a free, no-obligation survey to assess whether your existing sash windows are suitable for double glazing.

How Much Does It Cost to Double Glaze Existing Sash Windows?

The cost of double glazing existing sash windows depends on the condition of your current windows, the size of the glazing units required and whether any restoration work is needed before installation.

Factors that may affect the overall cost include:

• The number of windows being upgraded.
• The size and style of each sash window.
• The condition of the existing timber frames.
• Whether repairs or refurbishment are required beforehand.
• Listed building or conservation area requirements.

At Mortice & Green, every project begins with a free, no-obligation site survey, allowing us to assess your windows and recommend the most suitable solution. If your existing sash windows are structurally sound, retrofitting slimline double glazing is often a highly cost-effective alternative to complete window replacement, allowing you to preserve your property’s original character while benefiting from improved insulation, reduced noise and greater energy efficiency.