Often referred to as the eyes of a house, windows play a vital role in defining the character of a period property. Key components of overall appearance, they are inextricably linked with architectural style and it is often through examining windows that you can determine the age of a building.

Whether you hope to restore your original windows, or invest in new designs that will complement a period home, this article contains everything you need to consider.

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The Heritage Window Company's Conservation slimline aluminium windows

Conservation slimline aluminium windows, from £1,500 each, The Heritage Window Company

Should I repair or replace my old windows?

Original windows were made using traditional techniques that are hard to imitate today due to modern building regulations, and their unnecessary replacement erodes the character of period homes. This means it’s vital that very effort is made to preserve and maintain original windows where possible.

Single-glazed windows are often replaced with double glazing due to a fear of inefficiency. But you are unlikely to ever see a return on fuel bills, while the originals could have been upgraded. However, if they are too rotten to repair, inappropriate modern designs are present, or you are extending, you need to source authentic-looking new designs.

How much do new windows cost?

Windows are priced individually, but for the purposes of working out rough costs over large areas, these estimates are presented in metre square.

  • Softwood casements: from £200 to £350 per m2
  • Hardwood casements: from £350 to £500 per m2
  • Timber sash windows: from £800 to £3,000 per m2
  • Metal windows: from £300 to £600 per m2
Ventrolla renovated sash windows

Renovated and draughtproofed original sash windows. From £500 per window, Ventrolla

Timber windows from Totali

totali timber casement window

Timber window frames are a durable, low maintenance choice for contemporary and period properties, providing a timeless look for your home. The performance gap between man-made products and wood has closed in recent years due to manufacturing developments, including the use of new materials and finishes.

Timber now offers a competitive, stylish and effective alternative to uPVC. A long term investment, timber windows also boast eco-friendly credentials and thermal efficiency due to being a naturally insulating material. For many; the most pleasing thing is the way wooden windows look and having the option to paint them in any colour. www.totali.uk.com

How can I upgrade existing windows?

Old windows inevitably face threats such as warping, rotting, sticking, chipping and corrosion. In addition, many homeowners complain of draughts and high energy bills. But before automatically replacing, look at measures to repair and upgrade them

Energy is lost through windows in two ways: by heat passing through the glass and by warm air escaping though gaps in and around the frames.

‘If wood windows are in a reasonable condition, they can be draughtproofed and repaired,’ says Richard Dollar, managing director of The Sash Window Workshop. ‘This improves functionality, security and efficiency at a fraction of the cost of replacement.’

Occasionally, individual panes of existing windows can also be substituted for insulated glass units (IGUs).

To further improve performance, look at fitting secondary glazing, which involves adding a slimline pane of aluminium-frame glass to your existing windows. It’s a cost-effective, efficient way to insulate and sound-proof windows without impacting on their character. Try a company that produces discreet bespoke designs, such as Storm.

Architectural Bronze Casements doors and windows

As part of a renovation, bronze windows and doors by Architectural Bronze Casements were added to this property. The double doors are surrounded by side and fanlights. Expect to pay £7,710 for a set of double doors, £420 for H110xW55cm fixed windows, and £540 for opening

What are the different window styles?

The most familiar window types in period homes are side-hung casements – wood or metal – which swing open like a door, and vertical sliding timber sash windows, which consist of two frames or ‘sashes’, each with panes of glass held together by wooden glazing bars, which slide vertically in grooves and are held open by weights and pulleys concealed in a timber box frame (although early sashes were held open by pegs).

Manufacturing techniques developed over the centuries to allow for larger glass sections, which were cheaper and more readily available, so early windows had small panes and later windows usually had larger panes.

The glazing is as important as the frame, and imperfect original glass adds its own unique character. Stained glass panes are sometimes present.

Sash window types

Sash window styles
  • Sash windows reigned supreme from the Georgian to Victorian eras, first in eight-over-eight or six-over-six pane configurations (1), and eventually two-over-two (2) or one-over-one. Sometimes multiple panes were used in the upper sash, with a large pane in the bottom half (3)
  • In the Victorian era, sash horns were introduced on the bottom edges of upper sashes to take the additional strain caused by the lack of glazing bars and heavy glass panes (see 2).
  • Bay windows (2) were hugely popular in the Victorian era.
  • Side sliding sash windows (4) were common in some regions, such as Yorkshire.

Pictures, from left: Westbury, Totali, The Original Box Sash Windows Company, Scotts of Thrapston

Casement window types

Different types of casement windows
  • In Tudor homes, small ‘lights’ in a leaded lattice framework (5) – usually diamonds or rectangles – set into stone or timber openings, are authentic.
  • Casement windows continued to be used in small, rural dwellings and in the late-18th and early-19th century. Later casements increasingly had larger panes and timber glazing bars.
  • The Victorians often adorned the upper halves of their windows with elaborate glazing bar designs and shaped windows heads, such as Gothic arches (7).
  • In the 1930s, steel Crittal-style windows were widely used (8).

Pictures, from left: Deacon & Sandys, Architectural Bronze Casements, Deacon & Sandys, Clement

Mumford & Wood’s Conservation Venetian- style windows

Mumford & Wood’s Conservation Venetian- style windows are made from knot-free engineered timber, with either a spring sash or traditional cord and weight operation. Priced from £7,440 for a H190xW100cm window, including side sashes

Which material is best for new windows?

With few exceptions, uPVC windows do little to enhance the appearance of older buildings, so ideally look to replacement wood or metal frames.

‘Timber windows offer a huge range of benefits beyond style and design flexibility, such as thermal performance and a long life,’ says Tony Pell, senior product manager at Jeld-Wen. Hardwood frames are considered the most long-lasting, although chemically improved softwood, known as Accoya, now rivals hardwood in durability.

Metals, such as steel, bronze and aluminium, also offer exceptional stability and strength, and include a thermal break to produce a highly energy-efficient and often maintenance-free window.

Clement leaded windows

Decorative leadwork on steel windows set within timber frame, prices on application, Clement

How to get the design right

With period properties, like for like is always best. If you are looking to rectify inappropriate windows, study nearby properties from the same era to ensure the style of window matches the rest of the building. Proportion, glazing bars and the glass itself all contribute to the character and overall appearance of a window, so all components must be addressed when thinking about replacements.

‘All aesthetic aspects should be considered, including selecting the right timbers, colours and decorative options, while also taking into account neighbouring properties so your home is in-keeping with its surroundings,’ says Sean Crane, head of surveying at Jack Brunsdon. If in doubt, ask your local conservation officer for advice.

A bespoke hardwood, triple-casement window featuring Gothic timber glazing bars from Clifton Joinery

A bespoke hardwood, triple-casement window featuring Gothic timber glazing bars costs from £1,800, depending on the frame option, from Clifton Joinery, based on a window around H100xW150cm in size

Choosing the right window furniture

totali monkey

Don’t stop at curtains and blinds when dressing up your windows. The right window furniture is essential to ensure security with instant style and elegance. This monkey tail fastener from the Totali Solutions range, is ideally suited to cottages, listed buildings and period properties. www.totali.uk.com

Do I need planning permission to change my windows?

Usually replacing period windows with like-for-like replicas will not require permission, but it may be needed where permitted development rights are restricted.

If you live in a Conservation Area, planners can be very particular about the new replacements being as close to identical as possible, and if there is an Article 4 directive, you will need to apply for permission.

Listed building consent is always required to replace windows in listed properties. To gain permission to replace any listed windows or doors, homeowners need to prove that the existing ones are beyond repair or that they are experiencing too much heat loss.

Take advice from a reputable company that has experience in window and door design and construction, and remember that planning officers can also advise on what is and is not acceptable.

Jeld-Wen cottage bar window

Jeld-Wen’s casement range offers a variety of glazing bar options, including Victorian, horizontal, Deco, cottage, Regency and all-bar. A choice of softwood or oak construction ensures there is something to suit all properties, and the windows are available in standard or bespoke sizes. £764 for a H104.5xW119.5cm cottage bar casement

Do they need to meet building regulations?

‘For complete new windows, the company making and installing them must be registered with FENSA,’ says Richard from The Sash Window Workshop.

‘If your current windows have trickle vents – small ventilation holes in the frame – you will need to ensure that the new windows have them or there are alternative sources of background ventilation.

‘Windows near floor level must contain safety glass (toughened or laminated) and must include the relevant safety mark clearly visible.

‘Once the work has been carried out you should receive a FENSA certificate through the post, which you will need if you sell the property in the future.’

To meet building regulations the amount of heat that can pass through the glass and framework is measured as a U-value and this has an effect on the efficiency of the window. For a listed building there is some flexibility in the U-value, in the interest of preserving traditional character.

New sashes or casements fitted into existing frames are classed as refurbishment, and so this work does not require certification.

Jack Brunsdon redwood flush casement windows

Redwood flush casement window in Fired Earth’s Nordic Light, from £3,200, Jack Brunsdon

Single or double glazed?

There are companies that use age-old methods of manufacture using single glazing for listed properties. However, in order to comply with building regulations, most new windows are now supplied with double glazing for increased energy efficiency. This can cause issues with authenticity and elegance, as frames and glazing bars often have to be widened to accommodate them.

Traditional leading also cannot be achieved with double glazing, but instead companies offer applied leaded detailing to get the look.

The glazing industry is continually innovating to improve the issue, which means that double glazing units are being developed that are thinner than ever, such as Slimlite, allowing for more elegant designs.

Triple glazing is another option for new windows that will enhance comfort inside. The sections will look too thick for authentic windows, but it can be a good solution for casements on some extensions, newer period-style houses and less historically important older homes.

Green Building Store triple glazed windows eyebrow dormers

For a low-carbon, energy-efficient solution, Green Building Store’s Performance triple-glazed windows offer exceptional thermal insulation. Fashioned from FSC redwood or oak, bespoke designs allow for period authenticity, as in these Arts and Crafts-inspired eyebrow windows, which feature interstitial glazing bars. From around £270 per m² for an opening window

Bespoke windows or off the shelf?

The most cost-effective option is to buy ready-made timber windows off the shelf. ‘Opt for made-to-measure windows if you can’t find what you’re after in standard sizes, or to address quirks or unusual shaped openings,’ says Tony Pell. ‘This also enables you to specify in-keeping double-glazed designs.’

Deacon & Sandys leaded light window behind oak barred opening

Traditional leaded light fitted behind original oak barred opening. Windows from £600, Deacon & Sandys

How can I ensure they are secure?

‘All new windows should be fitted with appropriate locks,’ says Richard Dollar. ‘Ground floor window locks should be key operated, whereas windows on the first floor should have egress locks.’ Do ensure any surface locks are secured to the frame rather than the window, and sashes are fitted with stops and bolts. Alternatively, an integral locking system located within the frame can offer greater security. Toughened safety or laminated glass is an option if extra security is required.

For added peace of mind, check out suppliers accredited to the Secured by Design (SBD) scheme – a police-led initiative that guarantees enhanced security features.

Clement EB24 steel window

EB24 steel window with 24mm double-glazed unit with oval leads, from £480, Clement


Words Melanie Griffiths and Pippa Blenkinsop. Additional copy by Elizabeth Bailey and Paula Woods

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