Single to Double Glazed Sash Window Upgrades
Single to Double Glazed Modern comfort, traditional charm—without replacing your windows
Upgrading your sash windows doesn’t mean replacing them. At Cavendish & Cole, we offer a specialist single to double glazed upgrade service—carefully transforming your existing timber sashes into high-performance, energy-efficient windows, while preserving the character and craftsmanship of your period property.
Whether you live in a listed building, conservation area, or a cherished Victorian or Georgian home, our discreet upgrade solutions deliver the warmth and comfort of modern double glazing, without altering the heritage aesthetics that make your home unique.
Preserve Your Original Windows
—Improve Their Performance
If your windows are structurally sound but poorly insulated, there’s no need for full replacement. We carefully remove the existing single glazing and fit Slimlite double glazed units directly into the original sash frames. This method allows you to retain the original joinery, historic details, and visual appeal—while dramatically improving thermal and acoustic insulation.
Our Single to Double Glazed upgrade service includes:
- Removal of old putty and single panes
- Precision fitting of ultra-slim Slimlite glass units
- Refitting with traditional putty for a seamless finish
- Refurbishment of existing sashes, including repairs if needed
- Replacement of sash cords, fixtures and fittings
- Discreet draught-proofing for additional comfort
Why Slimlite Glass?
Slimlite double glazing is designed for heritage properties. These ultra-thin, gas-filled units replicate the appearance of single glazing while offering U-values that meet modern standards.
- Ideal for sash windows with narrow glazing bars
- Accepted in many listed building and conservation applications
- Reduces draughts, heat loss, and condensation
- Significantly improves energy efficiency
- Helps reduce external noise without thick, bulky units
We can advise on planning considerations and liaise with your local authority if permission is required—especially for properties with heritage status or listing under English Heritage guidelines.
A Sustainable Approach to Window Upgrades
Our single to double glazed sash window upgrades offer an environmentally responsible solution. By refurbishing and upgrading rather than replacing, we minimise waste and reduce the carbon footprint associated with full window manufacturing and installation.
We use high-quality materials and sustainably sourced timber, including durable, low-maintenance options such as Accoya, which resists warping and offers decades of reliable performance.
Heritage-Friendly. Homeowner Approved.
Many of our clients choose to upgrade to double glazing because they want to stay warm and reduce energy bills—without spoiling the look of their home. With Cavendish & Cole, you can have both.
- Retain your home’s historic look and feel
- Meet energy standards without full replacement
- Avoid unnecessary planning delays
- Improve comfort, security, and value
From initial survey to final polish, every project is managed by our trusted in-house team, with a focus on quality, clarity, and craftsmanship.
Ready to transform your home?
Call us on 01273 282176 or email us here
Get in touch today for a free consultation. Let’s bring your vision to life—beautifully, traditionally, and made to last.
Get In Touch
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Contact Us
- Brighton, East Sussex
- info@cavendishcole.co.uk
- 01273 282176
Cavendish & Cole
Additional Services
At Cavendish & Cole Timber Sash Windows & Doors, we specialise in the design, manufacture, and installation of beautiful bespoke sash windows,
Using ultra-thin Slimlite units, our double glazed sash windows maintain the narrow sightlines and slender glazing bars characteristic of Georgian and Victorian sash windows
Whether you live in a listed building, conservation area, or a cherished Victorian or Georgian home, our discreet upgrade solutions deliver the warmth and comfort of modern double glazing, without altering the heritage aesthetics that make your home unique.
Discreet double glazing designed for traditional sash windows When it comes to upgrading sash windows in period or listed properties, finding a glazing solution that delivers energy efficiency without compromising aesthetics can be a challenge.
All our glazing is selected for quality, energy efficiency, and visual compatibility with period-style joinery. We work closely with homeowners, architects, and conservation officers
Living in a bustling town, near a main road, or under a flight path doesn’t mean you have to sacrifice peace and quiet—nor the classic style of your sash windows.
Privacy glazing is a common requirement in bathrooms, cloakrooms, and entryways—but standard modern options often look out of place in traditional homes. That’s why we source a range of authentic obscured and patterned glass styles that work in harmony with Georgian, Victorian, and Edwardian architecture.
If you're renovating a period home or looking into sash window repairs or replacements, you’ll quickly come across a number of technical terms — some of which can sound confusing at first.