Upgrading the windows in a period home can feel like a bit of a balancing act. You want a warmer, quieter and more comfortable house, but you also do not want to lose the details that made you fall in love with the property in the first place.

For Victorian, Edwardian, Georgian and other traditional homes, the windows can be one of the most important features of the exterior. Sash windows, bay windows, timber casements, decorative glazing bars and original glass all contribute to the character of the building.

The good news is that improving the thermal performance of a period home does not necessarily mean replacing everything with modern-looking windows.

There are several options available, from repairing and draught-proofing existing windows to installing secondary glazing, slim-profile double glazing or completely new windows designed to replicate traditional styles.

So, what are the options for double glazing in a period home, and which is likely to be right for your property?

Why are period homes more difficult to double glaze?

Older properties were built at a time when windows were designed very differently from modern units.

Traditional sash windows, for example, often have slim glazing bars and relatively shallow frames. Original casement windows can also have much narrower sections than a modern double-glazed window.

Standard double-glazed units are usually thicker than single glazing. This can create a problem when trying to fit them into an original frame without changing its proportions.

That is particularly important in period properties because the appearance of a window is not just about the glass. The frame, glazing bars, opening arrangement and overall proportions all contribute to how authentic it looks.

Historic England notes that some traditional windows may not have enough depth or width in the glazing bars to accommodate even slim double-glazing units. In these cases, secondary glazing can provide an alternative without altering the original window.

This is why there is no single answer to the question of which double glazing is best for a period home. The age and style of the property, the condition of the existing windows and any planning or conservation restrictions all need to be considered.

What are your options?

When improving the windows in a period property, there are generally four routes to consider:

• Repair and draught-proof the original windows
• Install secondary glazing
• Replace the glass with slim-profile double glazing where suitable
• Replace the windows with new, traditionally styled double-glazed windows

Each has its advantages, and the right choice depends on what you are trying to achieve.

1. Keep the original windows and improve them

Before looking at replacement windows, it is worth asking whether your existing windows actually need replacing.

A well-made timber window can have a surprisingly long lifespan, particularly when it has been maintained properly. Some traditional timber windows can be repaired, repainted and draught-proofed rather than removed.

Draughts are often a bigger problem than homeowners realise. Gaps around moving parts and between the frame and opening can allow cold air into the house, making rooms feel colder even when the heating is on.

Draught-proofing can therefore make a noticeable difference without changing the appearance of the property.

Historic England recommends considering repair and draught-proofing as part of an approach to improving the energy efficiency of older windows.

This can be particularly worthwhile if your windows are original and still in good condition.

However, repairing the windows will not give you the same glazing performance as a modern double-glazed unit. If thermal performance is the main reason for upgrading, you may want to consider one of the options below.

2. Secondary glazing

Secondary glazing is often overlooked because it is not technically a replacement window.

Instead, a second pane of glass is installed on the inside of the existing window. Your original window remains in place, while the additional glazing creates another layer between the inside of your home and the outside.

For period properties, this can be an extremely useful solution.

The biggest advantage is that the external appearance of the house remains unchanged. Original sash windows, decorative glazing bars and historic glass can all be retained.

It can also work particularly well in conservation areas or on listed buildings where replacing original windows may be restricted.

Historic England recommends secondary glazing as an important option for improving the energy efficiency of traditional windows. Its research has found that carefully designed secondary glazing can reduce heat loss through windows by more than 60%, while also improving sound insulation.

There are different types of secondary glazing available, including discreet systems designed specifically for traditional sash windows. Some can be fitted with very slim frames, while removable systems are also available.

The main consideration is the interior of the room. Because the secondary glazing sits inside the existing window, you need to think about how it will interact with shutters, curtains, window furniture and existing mouldings.

For a period home where preserving the original windows is the priority, however, it can be one of the most sympathetic options.

3. Slim-profile double glazing

If you want the performance of double glazing but would prefer to retain existing frames, slim-profile units may be worth investigating.

As the name suggests, these double-glazed units are thinner than standard modern units. This can make them more suitable for traditional windows where space is limited.

There are limits, though. Not every original frame will be suitable, and the condition and construction of the window need to be assessed before deciding whether the glass can be replaced.

Historic England’s current guidance recognises slim-profile and vacuum double glazing as possible options for historic buildings, while noting that the suitability of the existing frame and the significance of the window need to be considered.

This can be particularly useful where the existing window is worth retaining but needs improved thermal performance.

However, replacing the glass is not always straightforward. The additional weight of double glazing can affect traditional opening mechanisms, particularly sash windows, which may require adjustments to the counterbalancing system.

If you are considering this route, it is worth getting specialist advice rather than assuming any existing timber window can simply be converted to double glazing.

4. Replace the windows with new traditional-style double glazing

For some period homes, replacement windows are the most practical option.

This does not necessarily mean choosing a modern-looking window. Traditional double-glazed windows are available in designs based on the proportions and detailing of older windows.

For example, a Victorian home may suit sliding sash windows or traditional casements, while an Edwardian property may have originally featured larger areas of glazing and simpler decorative detailing.

The aim should be to replace the performance of the old window without losing the character of the property.

This is where material becomes important.

Timber double glazing

Timber remains a popular choice for period properties because it can closely replicate traditional window designs.

A well-designed timber window can retain slim sightlines, traditional proportions and detailed joinery while incorporating modern double glazing.

For a homeowner restoring a Victorian or Edwardian property, timber can be a particularly natural choice when authenticity is important.

It also gives you flexibility over paint colours and finishes, which can be useful when matching existing architectural details.

Timber alternative double glazing

Timber alternative windows are another option for homeowners who like the appearance of traditional timber but want a lower-maintenance material.

Modern timber alternative windows can reproduce the proportions and detailing associated with traditional windows while offering durability and easier maintenance.

For period homes, the detailing is particularly important. A window can technically be the right style but still look wrong if the frame is too bulky or the glazing arrangement is not appropriate.

The best timber alternative windows are designed with these proportions in mind.

uPVC double glazing

uPVC is often chosen for its durability, low maintenance and generally competitive price.

Modern uPVC windows are available in traditional styles, including casement and sash designs, so they can work well in some period properties.

They are not automatically the wrong choice for an older home. What matters is how closely the design suits the property.

Slimmer frames, appropriate glazing bars and traditional opening arrangements can make a significant difference to the finished appearance.

However, in particularly sensitive historic buildings, the detailing and material may need more careful consideration. Historic England points out that traditional windows can have thinner sections and different detailing from uPVC replacements, which can affect the appearance of an older building.

What about sash windows?

Sash windows are one of the most recognisable features of many Victorian and Georgian homes, and replacing them requires particular care.

The proportions of the sashes, glazing bars and meeting rails all affect the appearance of the window.

If the original sash windows are in good condition, repairing them, draught-proofing them and adding secondary glazing can be a very sympathetic approach.

Where replacement is necessary, modern double-glazed sash windows can provide the traditional appearance with improved insulation, security and ease of use.

There are also different approaches to sash windows depending on the property. Timber sash windows offer the most traditional material, while modern alternatives can reduce maintenance.

The important thing is to look beyond the words “double glazed sash window” and examine the actual design. The width of the glazing bars, depth of the frame and overall proportions can make a considerable difference.

Choosing double glazing for Victorian and Edwardian homes

The age of your home can give you a useful starting point.

Victorian homes

Victorian properties can vary enormously, from simple terraces to highly decorative villas.

Traditional sliding sash windows are common, but casement windows also appear on many Victorian homes.

Timber sash or casement windows can be a good choice where authenticity is the priority. Timber alternative and uPVC options may also work where the design closely reflects the original architecture.

If the property has decorative original glass, it is worth considering whether it can be retained rather than automatically replacing it.

Edwardian homes

Edwardian architecture tends to have lighter and less elaborate detailing than many Victorian properties.

Windows can be larger, with more emphasis on natural light. Casement windows became increasingly common, often with leaded or decorative glass.

Double-glazed replacement windows can work particularly well where they reproduce these proportions without making the frames unnecessarily heavy.

For Edwardian homes, the goal is often less about recreating an elaborate Victorian appearance and more about maintaining the property’s balance and generous glazing.

What about listed buildings and conservation areas?

This is one area where it is important not to assume that replacing windows is simply a matter of choosing a style and ordering them.

Listed buildings have specific requirements, and changes to historic windows may require consent.

Conservation areas can also have additional considerations, particularly where windows make an important contribution to the character of the property.

Historic England advises that the significance of the existing window should be considered before replacement and that secondary glazing can often provide an effective way to improve performance while retaining historic fabric.

If your home is listed or located within a conservation area, check the relevant planning requirements before committing to replacement windows.

Which double glazing option is right for your period home?

There is no universal answer.

If your original windows are in good condition and preserving them is your priority, repair and draught-proofing may be the best place to start.

If you want to retain the existing windows but improve comfort and energy efficiency, secondary glazing can be a highly effective option.

If your existing frames are suitable, slim-profile double glazing may allow you to improve performance while retaining more of the original window.

And if your windows are beyond repair or have already been replaced with unsuitable modern windows, new double-glazed windows in a traditional design may provide the best long-term solution.

The important thing is to consider the whole window rather than just the glass. Frame proportions, glazing bars, opening style, materials and detailing all contribute to how a period home looks.

Finding the right windows for your period home

Double glazing has come a long way, and upgrading the windows of an older property no longer has to mean choosing between energy efficiency and character.

For some homes, the best solution will be carefully retained original windows with secondary glazing. For others, new timber, timber alternative or uPVC windows may provide the right balance of appearance, performance and maintenance.

The starting point should always be the property itself.

Look at the age and architectural style of the house, the condition of the existing windows and the features that make the property distinctive. From there, it becomes much easier to decide which approach makes sense.

At Elwyns, we have been helping homeowners choose windows for traditional and period properties for over 60 years. We offer timber, timber alternative and PVC windows in a range of traditional styles, including sash and casement designs, so there are options for different homes and priorities.

If you are considering double glazing for a period home, visit one of our showrooms or speak to our team about the options available for your property. We can help you compare materials, styles and glazing options and find a solution that improves your home without losing what makes it special.

Choosing the right window style is one of the most important decisions a period homeowner will make. Windows do more than let in light, they set the rhythm and proportion of a façade, frame the character of a property, and often say more about a home’s age than almost any other feature. Get the style wrong, and even the best-quality double glazing can look out of place. Get it right, and you can dramatically improve comfort and efficiency while keeping a home looking exactly as it should.

Whether you’re restoring a Georgian townhouse, updating a Victorian terrace in Dulwich, or renovating a larger Edwardian or Arts and Crafts property in Surrey, the window style you choose needs to reflect the era the house belongs to. Below, we’ve put together a guide to the most common traditional window styles, what they suit, and the systems we install at Elwyns to help you achieve the right look.

Why window style matters more than material

It’s easy to assume that choosing a period-appropriate window is mostly about picking the right material, timber over PVC-U, for example. In reality, style and proportion matter just as much, if not more.

A window with the correct number of panes, the right glazing bar width, or an authentic horn detail will often look more convincing in the wrong material than a poorly proportioned window in the “correct” one. That’s why, before choosing a material or brand, it’s worth understanding which window style actually belongs on your property in the first place.

Vertical sliding sash windows

The sash window is arguably the defining feature of British period architecture, used from the late 1600s right through to the early 20th century. It consists of two vertically sliding panels, traditionally counterbalanced with weights and pulleys hidden inside the frame.

Sash windows suit an enormous range of properties, from Georgian townhouses to Victorian terraces and Edwardian villas, though the glazing pattern changes considerably across each period.

We offer sash windows in two operating systems. Traditional balanced weights replicate the original cord-and-pulley mechanism found in period homes, giving the most authentic feel and operation. Spring balanced systems use modern spring mechanisms instead of weights, offering smoother, lower-maintenance operation while keeping the same external appearance.

Both are available through our Timber Windows range, and as a Quickslide PVC-U sash for a lower-maintenance alternative, including a woodgrain effect finish that mimics painted timber.

Best for: Georgian, Victorian and Edwardian properties, particularly on street-facing elevations where authenticity matters most.

Georgian glazing bar patterns

Georgian sash windows (roughly 1714–1830) are defined by their multi-pane glazing, most commonly a six-over-six pattern, though eight-over-eight and twelve-over-twelve patterns appear on larger properties. The glazing bars themselves are typically thin and crisp, a reflection of the smaller panes of glass available at the time.

Symmetry is key to Georgian façades, so window proportions tend to be tall and evenly spaced, often decreasing slightly in height on upper floors.

Our Timber Windows range can be specified with authentic Georgian glazing bar patterns and slimline double glazing, preserving the delicate look of the original panes while improving thermal performance.

Best for: Georgian townhouses and terraces, and later properties built in a Georgian revival style.

Victorian sash windows

By the Victorian era (1837–1901), improvements in glass manufacturing allowed for larger panes, and the classic six-over-six pattern gave way to simpler two-over-two sashes, or in many cases a single large pane in the lower sash with margin lights around the upper one.

This period also introduced the horn, a small decorative extension at the base of the upper sash meeting rail, which became necessary once thicker glass required stronger horned joints. A window without horns on a Victorian property is one of the most common giveaways of an inauthentic replacement.

Coloured, etched or stained glass also became popular on Victorian entrance doors and hallway windows, adding a distinctive decorative touch.

Our Timber Windows range replicates horned joints and traditional Victorian glazing patterns closely, while Evolution timber-alternative windows offer the same detailing with lower long-term maintenance, a popular choice for larger Victorian terraces and semis with multiple windows to maintain.

Best for: Victorian terraces and semi-detached homes, particularly in South London’s many Victorian suburbs.

Edwardian windows

Edwardian properties (1901–1910) moved slightly away from strict Victorian symmetry, often featuring wider window openings and a fondness for small-paned upper sashes sitting above larger, single-pane lower sashes. Leaded lights and stained glass were used more decoratively, particularly in bay windows and porches.

Edwardian homes also tend to have slightly wider frame sections than their Victorian predecessors, so it’s worth choosing a system that can replicate this without appearing bulky.

Both our Timber Windows and Evolution ranges can be specified to match Edwardian proportions, including the small-paned upper sash detailing that defines the period.

Best for: Edwardian villas and semis, particularly those with bay window features.

Bay windows

Bay windows became especially popular from the Victorian period onwards and remain one of the most recognisable features of British suburban architecture. Square, canted (angled) and curved bays each became fashionable at different points, with canted bays being particularly common on Victorian and Edwardian terraces.

Because a bay window combines several window units at different angles, getting consistent glazing bar alignment and colour matching across the whole bay is important for a cohesive look.

Bay windows can be specified across our Timber Windows, Evolution, Whiteline and Quickslide ranges, allowing homeowners to match whichever style and material suits the rest of the property.

Best for: Victorian and Edwardian terraces and semis with existing bay window openings.

Casement windows

While sash windows dominate much of Britain’s period housing stock, casement windows, hinged at the side and opening outward. These were also common, particularly on cottages, Arts and Crafts properties, and rural period homes.

Traditional casements are typically taller and narrower than modern equivalents, often divided into smaller panes by glazing bars, and finished with traditional stays and casement fasteners rather than modern espagnolette handles.

Our Timber Windows range offers traditional casement styles with authentic ironmongery, while Whiteline provides a PVC-U casement option with foiled woodgrain finishes and heritage colours for homeowners wanting a lower-maintenance alternative.

Best for: Arts and Crafts homes, cottages, and rural or village period properties.

Crittall-style steel windows

Popular through the 1920s and 30s, slim steel-framed windows became a hallmark of Art Deco and later Edwardian properties, prized for their narrow sightlines and industrial, geometric character. Original crittall windows are notoriously poor performers thermally and are prone to rust, making replacement a common priority for owners of these properties.

We install Aluco, our dedicated steel-look aluminium collection, specifically to replicate the narrow, elegant profiles of original crittall windows while delivering vastly improved thermal performance and none of the maintenance headaches of steel.

Best for: Art Deco and 1920s–30s properties, and any period home originally fitted with crittall-style windows.

Window shutters

While not a window style in themselves, shutters are worth mentioning as they were a common feature on Georgian and Victorian properties, both externally and internally, used for security, insulation and light control before curtains became widespread.

Interior panelled shutters remain popular on period homes today, adding authenticity and a useful layer of insulation and privacy, and can be fitted alongside any of the window styles above.

Best for: Georgian and Victorian properties wanting to reinstate an authentic period feature.

Matching window style to render, brick and stone

Beyond the window itself, it’s worth considering how your chosen style will sit against the existing façade.

Exposed red or London stock brick tends to suit slim glazing bars and traditional horned sashes, where the contrast between brick and painted timber does much of the visual work.

Painted or rendered properties offer more flexibility, often suiting bolder colours or a wider range of styles, from Georgian multi-pane sashes to simpler Edwardian casements.

Stone-fronted properties, more common in the South East on larger period homes, often suit taller, more formal sash proportions with minimal glazing bar detail.

Conservation areas and listed buildings

Many period homes with traditional window styles sit within conservation areas, and some are listed. As with front doors, replacing windows on a like-for-like basis is usually considered permitted development in a conservation area, but the local authority will often expect the replacement to match the style, proportions and materials of the original as closely as possible.

On listed buildings, replacing original windows typically requires listed building consent, which isn’t always granted even for high-quality timber replacements. In these situations, slimline double glazing or secondary glazing fitted within the existing frame are often the only realistic options a conservation officer will accept.

It’s always worth checking with your local planning department, or discussing your specific property with your installer, before finalising a specification.

Choosing the right window style for your home

The best window style for a traditional home isn’t necessarily the most decorative or the most expensive, it’s the one that reflects the age and character of the property accurately, whether that’s a Georgian six-over-six sash, a horned Victorian two-over-two, or a crittall-style steel window on an Art Deco villa.

At Elwyns, we work with homeowners across South London and Surrey to identify the right style for their property before discussing material and brand. Whether that’s Timber Windows or Evolution for the most authentic period detailing, Whiteline or Quickslide for a lower-maintenance PVC-U alternative, or Sheerline, Air and Aluco for aluminium and steel-look solutions, our team can help you find a window that looks right for the age of your home and performs well for decades to come.

Contact us today to arrange a free quote.