January 25, 2021


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Learn all You Should Know about Sash Windows

Sash windows can be a timeless feature to any home. Here, KJM Group explains the sash windows’ elegant style, their history, when they should be replaced or restored, and how to pick out new ones.

If you are renovating a Victorian, Regency, or Georgian property, then this item needs to be a high priority for your shopping list.

What are Sash Windows and How do they Work?

The very word ‘sash’ is a reference to a singular frame for glazing. Traditional sliding sash windows had a pair of sashes sliding up and down. In simple terms, this kind of window would function by balancing its sash with an opposing counter-weight of cast iron, steel, or leaden weight that hangs on a cord but is concealed inside a hollowed-out box frame. It’s possible to retrofit insulation into these pockets for older windows.

This is certainly a classic design and one most frequently seen in Georgian properties, although variations can also be seen in some variations of later Edwardian and Victorian houses.

Sash Window Styles

When you replace the windows of any older property, or you’re choosing the aesthetic for your period-style residence, then you need to proceed with caution so you can be sure you get the proper time period. Sash windows have gone through a number of stylistic evolutions through the course of their history, so be mindful of this lest you get caught off guard.


Sashes normally comprise of several small panes known as ‘lights’. Glazing or astragal bars hold these all together in order to form up a broader glazed area. This happened because glass technology back then didn’t permit broad expanses using clear glazing.

Should Sash Windows be Repaired or Replaced?

Whenever possible, avoid removing any sashes using original period timber in lieu of modern replacements. It’s far better to first restore and then waterproof an existing sash if it’s at all possible.

The advantages of doing repairs when practical include:

-A home keeps its original character and charm

-Homeowners can take advantage of enhanced thermal performance thanks to draught-proofing and double glazing when a box frame gets retained with replacement glazing

-The original timber is likely to be of superior quality to modern products

Expenses Involved in Replacing and/or Restoring Sashes

Glazing might be replaceable in sash windows when the original frames prove to be salvageable. If you can renovate something to a relatively prime condition, then you might be able to upgrade single-glazed panelling to a thin double glaze. New sashes that can be fitted into your existing frames are possible, with estimates starting at £1,000 per window.

What Kind of Material is Best for Replacement Sash Windows?

Timber Sashes

If you live inside a conservation area or building, or you’re just a traditionalist, then you should opt for authentic timber sash windows. In fact, they should be your only real option, because while plastic offers many benefits, it just doesn’t have a similar tactile effect. Some of the benefits of timber include:

  • Durability
  • A great insulator
  • When maintained appropriately, long service life.

PVCu Sash Windows

PVCu is also known as uPVC and sometimes used as something to substitute in place of painted wood. Even though these are frequently seen only in white, there are in fact a wide variety of finishes and colours, including one wood finish that is a photo-effect. Benefits include:

  • Low in maintenance
  • Energy efficiency (although not sustainably, as you can’t recycle them).

Composite Sash Windows

Using composite sash windows is a growing trend. Cutting-edge products have exterior aluminium cladding with timber interiors. Benefits to composite windows are:

  • They keep the classic appearance of wood on their inside
  • Exteriors are very low in maintenance needs or requirements.

Sash Window Glazing

Current building regulations unfortunately make it really difficult to get single-glazed windows installed with a new home construction. That means that you might have to sacrifice your dream of the genuine article. However, you can install single-glazed windows in many renovation scenarios.

Sash Window Double Glazing

Partitioning tiny double-glazing units, especially with thick bars, has a tendency to look awkward. However, you can employ several methods that recreate the look of fine-glazing bars effectively. The ideal method is bonding mock bars on the side of one double-glazed unit. You might also use spacer bars in between your glass sheets; it costs more, but it does add successfully to the overall effect you are looking for.

Triple-Glazed Sash Windows

Triple-glazed possibilities come in traditional styles, although things are often priced to a premium in anything related to triple-glazed windows. On the other hand, modern triple glazing might not suffer under the cost stigma it earned decades ago.