It is as important to think about the function of a sash window as much as it the style. From restoring and incorporating modern glazing to replacing in a material faithful to the period, there’s a lot to consider. When material, cost and mechanism are carefully thought out, sash windows can enhance a traditional-style self build or conversion and transform a run-down renovation project.
They provide an unparalleled glimpse into past traditions but when designs are not matched to the correct period or originals are ripped out when they could be saved, it can affect character and charm of the house as a whole.
An inherent part of British architectural history, any styled property from the 17th to 19th centuries would be lacking without sash windows; if you’re renovating a Georgian, Regency or Victorian property, this item should be high on your shopping list.
What is a Sash Window and How Does It Work?
The word ‘sash’ refers to a single frame for glazing; a traditional sliding sash window features two sashes that slide up and down. In basic terms, the window works by balancing the sash with a counter-weight of steel, cast-iron or leaden weight hung on a cord which is concealed within a hollow box frame. Insulation can be retrofitted in these pockets in older windows.
This classic design is most commonly found in Georgian and Victorian properties, but can also been seen with variations in late Victorian and Edwardian houses. A very popular variation includes the horizontally sliding sash, known as a Yorkshire sash or a ‘slider’ window. This design actually pre-dates the vertical sash and although they use the same sliding mechanism, one of the sashes is usually fixed in place.
Styles of Sash Window
When replacing windows on an older property, or deciding on design for a period-style home, you must be careful to get the time period right. There were several developments and style changes in sash windows over the years so don’t get caught out.
Sashes traditionally consist of a number of small panes, or ‘lights’. These are held together by glazing bars – astragal bars – to create a larger glazed area. This is because glass advancements at the time didn’t allow for very large expanses of clear glazing.
The period of the sash will dictate the number of panes in each sash separated by astragal bars:
- Georgian: The ‘six over six’ style is quintessentially Georgian, although larger eight over eight’ windows were also common
- Victorian: ‘Two over two’ reigned supreme in Victorian times, but many other configurations can be also found through the whole period. This included sash windows with just a single light (shown below) as well as the inclusion of sidelights
- Edwardian: Typically ‘six over two’ panes was most common, but, as with the Victorian era, the Edwardians saw variations in style
Other variations in sash style include:
- Venetian windows which consist of a central sliding sash between two fixed panes either side
- The Queen Anne Revival styles incorporates several panes in the upper sash but just one or two in the lower
- Sashes were often arched instead of rectangular in Regency or Gothic revival periods, and it some regions it is popular to have horizontally-sliding sashes
Should I Repair or Replace Sash Windows?
Be careful not to make the mistake of removing the original period timber sashes and replacing them with new models. Always restore and waterproof existing sashes where possible.
However, if the windows are beyond repair or if there aren’t any left in place, many companies manufacture authentic replacements.
Benefits of repairing where possible:
- House retains original charm and character
- Homeowners benefit from improved thermal performance with double glazing and draught proofing if the box frame is retained and glazing is replaced
- Original timber is generally of better quality than the products we can purchase today
- Properly repaired timber windows can last another 100 years with a bit of care and attention
However, the decision to keep original sash windows is ultimately down to customer preference and budget.
Cost of Restoring or Replacing Sashes
Glazing can be replaced in sash windows if the original frames are salvageable. If able to renovate to a good condition, the single-glazed panels can be upgraded to slim double-glazed. Also new sashes can be fit into existing frames for which sash window repair specialists Ventrolla estimate anything from £1,000 per window.
For a complete replacement of sash window, cost will depend on specification (glazing types, choice of timber and any special feature of detailing required). Roughly, expect to pay from £1,750 per window.
What Material Should I Choose for a Replacement Sash Window?
Timber Sash Windows
For traditionalists or for those living in a Conservation Area or listed building, genuine timber sash windows are likely to be the first and only choice. Sadly, plastic cannot realise the same tactile effect.
- An excellent insulator
- Long lasting (if properly maintained)
- Modern finishes are available in most paint colours and stains and mean that timber windows are no longer high maintenance
PVCu Sash Windows
PVCu (sometimes seen as uPVC) is often used as a substitute for painted wood. Though most commonly seen in white, it comes in a wide range of colours and finishes, including a photo-effect wood finish.
- Low maintenance
- Energy efficient (but not sustainable as they cannot be recycled)
- Cheaper than timber (PVCu can cost around 40% less)
- Better quality models are more attractive and hard-wearing but difficult to repair
- Conservationists are, in the majority, opposed to plastic windows
Composite Sash Windows
It is becoming popular for sash windows to be composite in their construction. Newer products offer timber on the interior with aluminium cladding on the exterior.
- They retain the classic look of wood on the inside
- Outside are extremely low-maintenance
- Able to withstand all weathers
Glazing in Sash Windows
Modern building regulations make it near impossible to have single glazed windows on a new house, so you may have to sacrifice true authenticity. It is, however, possible to install single glazed windows on many renovations.
Double Glazing in Sash Windows
Dividing up small units of double glazing with thick bars tends to look clumsy, but there are ways to effectively recreate fine glazing bars. The best way is to bond mock bars onto either side of a single double glazed unit. You could also incorporate spacer bars between the glass sheets, at a higher cost, to add to the effect.
Triple Glazed Sash Windows
Triple glazed options are available in these traditional styles, but as with all triple glazed windows, it might come at a premium. However, modern triple glazing could be seen as no longer carrying the cost stigma that was attached for the last couple of decades. This is in the majority due to triple glazed windows being manufactured in mainland Europe where it is much more mainstream.
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Original timber sash and casement windows embody the charm and heritage of any period property, and that is why it is so important to ensure they remain in the best condition possible.
Draughts can be a common problem with original timber sash windows as they have a 3mm gap around the edge to ensure smooth operation. However, this does mean that heat escapes easily and wind, dust and water can enter.
Speak to a sash window specialist like Ventrolla, for advice on how to combat these common sash window problems without losing the appeal of their authentic charm.