Why are sash windows draughty?

Sash windows have been a favourite for homeowners for ages due to their timeless elegance and utility. However, one frequent issue that people encounter is draughty sash windows. In the following sections, we’ll dive into the main factors contributing to this problem.

Draughty Sash Windows

Poor Installation: A Root Cause

A major factor that contributes to draughty sash windows is poor installation. Even small errors can have a large impact over time. When sash windows are not aligned properly or if the sealant used during installation is substandard, it creates the perfect setting for draughts to infiltrate your home. Proper installation involves precise measurements and a keen understanding of materials involved, which is why hiring professionals for this task is so important. If you find that newly installed sash windows are draughty, this could be a red flag indicating poor installation.

The Impact of Wear and Tear

  • Loose joints
  • Cracked panes
  • Deteriorated sealing

No window is immune to the effects of time, and sash windows are no exception. Joints can loosen, wood can rot, panes can crack, and sealing can deteriorate. All of these issues create the perfect storm for draughts to make their way into your home. If you’re in a particularly windy area, the wear and tear can happen even faster. Keep a close eye on the state of your sash windows, and at the first sign of wear, consult a professional for either repair or replacement.

Outdated Design

While traditional sash windows have a unique aesthetic appeal, they often lack modern energy-efficient features. Many older designs were created before energy efficiency became a priority, resulting in a lack of effective insulation and sealing features. The absence of features like double glazing or thermal breaks contributes to sash windows being draughty. If you love the vintage look but want the advantages of modern technology, consider upgrading to sash windows with modern features. Consult with professionals to understand your options better.

Inadequate Insulation

Insulation is not something you can see, but you can certainly feel its absence when your home is draughty. Poorly insulated sash windows allow the cold air from outside to mingle freely with the warm air inside, causing uncomfortable draughts and higher energy bills. There are various types of insulation, such as foam tape and V-strip, that can be added to sash windows to improve their insulation. However, for a more permanent solution, it might be advisable to seek professional guidance on how to insulate your sash windows adequately.

Seasonal Changes and Their Effects

  • Wood expanding and contracting
  • Peeling paint
  • Rusting or corroding hardware

Sash windows are not static; they react to changes in temperature and weather conditions. During the colder months, wood can contract, creating small gaps that allow draughts to enter. Similarly, hot and humid conditions can cause wooden sash windows to expand, affecting how they fit into their frames. This misalignment creates an opportunity for draughts to enter. To keep your sash windows in prime condition, consider regular seasonal maintenance, ideally performed by professionals who can identify and address potential problems before they get worse.

A Guide to Fixing Draughts in Sash Windows

Dealing with draughty sash windows can involve multiple steps:

  • Weatherstripping: A cost-effective way to deal with small gaps.
  • Replacing Hardware: Sometimes the latches or locks are the culprits.
  • Reglazing: A more permanent fix, particularly for older windows.

Before diving into any of these, it’s imperative to understand the cause of the draughts. A professional assessment can pinpoint the problem, saving you time and potentially unnecessary costs in the long run.


While sash windows are a stylish and traditional feature in many homes, their susceptibility to draughts can be a disadvantage. Poor installation, wear and tear, outdated design, inadequate insulation, and seasonal changes are some of the primary factors contributing to this issue. The first step towards resolving this problem involves understanding its root cause, which is best achieved through a professional evaluation. By identifying and fixing the issues causing your sash windows to be draughty, you can enjoy a more comfortable and energy-efficient home.