The best heritage window options for your home
There are three main routes for heritage window replacement. The right one depends on the age and style of your property, what the existing windows are made from, and what your planning situation allows.
Sash windows the right choice for most period homes
Sliding sash windows are the most common window type in UK period properties. Georgian, Victorian and Edwardian homes were almost all built with them.
The style evolved over more than 200 years. A Georgian sash from the 1780s typically has six small panes in each sash, divided by slim glazing bars, with clean symmetrical proportions. A Victorian sash from the 1870s is taller and narrower, usually with just two panes per sash and decorative horns where the upper sash meets the stile. An Edwardian sash from the early 1900s often features a decorative top light with larger lower panes, influenced by the Arts and Crafts movement.
Timber sash windows are the most authentic option and usually the one required for listed buildings. Everest timber sash windows are available in softwood (European pine) or hardwood (African sapele), both responsibly sourced. The timber is laminated and engineered so the layers bond together for added strength, making them more dimensionally stable than the solid timber originals.
Timber sash can be fitted with slimline double glazing that sits within traditional rebates, achieving U-values of around 1.4 to 1.6 W/m²K. Compared to the 5.0 W/m²K of the single glazing it replaces, that's a reduction in heat loss of roughly 70%. Timber does require maintenance, typically repainting every five to seven years, but Everest timber windows are backed by a 30-year guarantee.
uPVC sash windows offer a lower-maintenance alternative. Everest uPVC sash windows use woodgrain finishes that replicate the look of painted timber. They operate with a spiral balance mechanism for the same sliding action as a traditional sash, and include a tilt function for easy cleaning. They're A-rated for energy efficiency and come with a 10-year guarantee.
A practical approach for many heritage homeowners can be to install timber sash at the front of the property where planning scrutiny is highest, uPVC sash at the rear and sides where requirements are often more relaxed.
Aluminium heritage windows for replacing original steel frames
Homes built during the 1920s, 1930s and into the post-war years often have steel-framed windows. Crittall windows named after the company that popularised them, are a defining feature of Art Deco and interwar architecture which is slim, geometric and elegant.
Original steel frames were single glazed, prone to rust, and thermally poor. The frames themselves conducted heat straight through to the outside and they always felt cold to the touch.
Standard uPVC frames cannot replace these slim profiles as the chunky profiles would completely change the proportions of the window openings and the character of the building.
Aluminium windows solve this. The strength of aluminium allows for very narrow frame profiles that closely replicate the slim sightlines of original steel. Modern aluminium heritage frames include a thermal break, a strip of insulating material (typically polyamide) built into the frame that stops heat transferring directly through the metal. It's a small engineering detail that makes a big practical difference.
These windows are available in a wide range of colours, though for heritage applications the finish should match the original. Black, bronze and dark grey are the most common for interwar and Art Deco properties.
Aluminium doesn't corrode like steel, doesn't rot like timber, and needs little more than occasional cleaning. A well-made aluminium window can last 40 years or more.
If your home has original steel frames that are rusting, single glazed, and struggling to keep the cold out, aluminium heritage windows are almost certainly the right path.
Secondary glazing for listed buildings where you can't change the originals
Some properties, particularly Grade I and Grade II* listed buildings, have original windows with genuine historic value. A local planning authority won't grant consent to replace them, and to retain the architectural integrity, they usually they shouldn't be replaced.
That doesn't mean you have to live with single glazing and draughts.
Secondary glazing is a separate glazed unit in a slim aluminium frame, fitted to the inside of the existing window opening. The original windows remain completely intact and unchanged from the outside. From the inside, you gain a significant improvement in both thermal performance and noise reduction.
The air gap between the original window and the secondary glazing creates a thermal barrier that reduces heat loss considerably offering considerable energy efficiency.
An added benefit is that secondary glazing is also particularly effective at reducing noise. The wider air gap between the two panes disrupts sound waves more effectively than a standard sealed double-glazed unit.
Everest secondary glazing uses fully glazed panels (unlike cheaper plastic versions) in slim aluminium frames. It's available as horizontal sliding sash, vertical sliding sash, hinged casement or fixed. All units are made to measure in the UK with a cost typically up to 50% less than full replacement windows.
Fitted internally without any alteration to the original windows, secondary glazing can be removed in future if needed without causing damage. That's important for maintaining the long-term value of historic fabric, and it makes the planning approval process significantly simpler.
