How To Stop Draughts From Double Glazed Windows

Double glazed windows

Double glazed windows are one of the most popular home improvement options, blocking intrusive sound and reducing the heat lost through a window, thereby lowering energy bills and increasing comfort. That said, the latter benefit is lost almost entirely when your window suffers from draughts. 

Are you looking up how to draught-proof windows? Ultra-Seal has put this post together to guide you through why draughts occur, how to stop them and the prevention of future draughts with your windows.

Why does my double-glazed window have a draught? 

There are several reasons as to why a double-glazed window may suffer a draught. The following are the most likely culprits:

  • Failed Seals – Your seals surround the edges of your double-glazed unit. Its purpose is to create an airtight, moisture-proof barrier to keep the argon gas within the unit, as well as prevent air from getting in. The seals, however, can be prone to things such as cracking, drying and shrinking over time. If this happens, not only is the inert gas leaking, which permanently reduces the insulation ability of your double-glazed unit, but cold air will start getting into your home.


  • Frame Damage – There are several different types of frames for double-glazed units, but the three most common are uPVC, Timber and Aluminium.


  1. uPVC – uPVC is acknowledged for its high durability, but it’s still plastic, meaning that when it’s too hot or too cold, it can expand and retract respectively. This could open up gaps in the window.
  2. Timber – Wood is a natural material whose weaknesses are very well-documented. It is fairly weak to moisture, with prolonged exposure leading to rot. Wet wood swells when infiltrated, and shrinks when dried out. The constant movement can cause warps and cracks in the window frame.
  3. Aluminium – Aluminium transfers heat fairly well. This means that cold on the outside can easily pass through the frame and create cold spots, and potentially, condensation within the frame. Good quality aluminium windows should have thermal breaks, however, which block heat transfer significantly.


  • Hinges – Hinges bear the weight of your window sash. Over time, they can wear out due to the constant friction of the opening, closing and weight, which runs the risk of windows sagging or becoming misaligned. This means that even if the window is fully closed, there will still be gaps allowing cold air inside.


  • Locking Mechanism – The locking mechanism is designed to pull the window tight against the frame, and within there are small hooks that pull the window sash tightly into the frame. If the locking mechanism is damaged, then the sash may not be manipulated, resulting in cold air infiltration.


How do I tell where the draught in my double-glazed window is coming from? 

It can be hard to determine the exact point of entry.

  • Candle Test – This is perhaps the most effective way to find the draught. Ensure there are no other sources of wind in the room. Light a candle and run it around the edges of your window slowly. If the candle flickers, you’ve found the draught. 
  • Hand Test – Run the back of your hands across the perimeter of your window frame. It may be worth doing it on both sides of the window if it’s on the ground floor. Nonetheless, your hands should be sensitive enough to feel the draught. 
  • Visual Inspection – Look for cracks, gaps, peeling sealant or signs of rotting wood visually. 
  • Listen up – If your home is quiet, you may be able to hear the draught. 


How do I make my windows draught-proof?

Draught-proofing windows is possible through DIY, although when the damage is extensive, your only option may be to call a professional. When you draught proof your windows, you must take care not to block window trickle vents, as this is how moisture leaves home.

Temporary DIY Fixes for Double-Glazing Windows

If you want to draught-proof your windows, the following are temporary fixes that you can do quite easily until later:

  • Draught Proof Tape – Self-adhesive foam/brush tape are two excellent temporary solutions. They can seal small to medium-sized gaps around the window frame, providing draught-proofing that can last anywhere from a few months up to a year, depending on the quality of the tape. The best part is – it’s incredibly easy to apply, nearly anyone can do it, making draught-proofing windows an easy, but temporary, job.
  • Window Film – Window films are clear plastic sheets that act like a shrink-wrap for your windows. You can apply it directly to your window using a solution and a squeegee. When it’s stuck, it’s usually recommended to use a hairdryer to shrink the film. Regardless, this method increases thermal insulation regardless of whether or not your window requires draught-proofing, but it will likely obscure the view from both sides.


Permanent Draught Proofing for Double-Glazing Windows

The following is the solution for permanently draught-proofing your windows.

  • Caulking – Caulking is a draught-proof and effective solution for fixing gaps and cracks around the window frame. To fix it, squeeze the caulk into small, irregular crevices. This creates a tight seal against the air, preventing leaks and draughts. For the outside of your window, use silicone caulk – it’s designed to withstand weather conditions.
  • Draught Proofing Strips/Weatherstripping – This provides a flexible seal where your window sash meets the window frame, draughtproofing windows and keeping your warm air inside. Compression strips made of foam/rubber strips with a V shape. They are self-adhesive, usually, for easy installation. Tension seals are metal strips with flexible fins, usually used for wood windows. Ensure you measure the gap and use the correct size. That being said, materials matter.
    • Foam – Self-adhesive Foam Strips are inexpensive and easy to install, best used for small gaps, but over time it loses durability. 
    • Rubber – This is a highly durable material that is excellent for sealing for various gap sizes. 
    • Vinyl – Vinyl is a rigid option that works well with sliding windows, but is much harder to install. 
    • Metal – Metal or plastic strips are mainly used for older wooden sash windows.
  • Hinge Adjustment – Over time, hinges wear and become misaligned. That being said, it’s possible to adjust them. The fix is simple, if a bit involved. Most hinges come with small adjustment screws. Tightening or shifting the hinge’s position can re-align the sash if you have sliding sash windows.
  • Lock Adjustment – Worn or misaligned locking mechanisms can prevent the window from pulling tight against the frame. This creates an opportunity for draughts to find their way in. That being said, they, too, usually have adjustment points. Tightening the mechanism or shifting the catch plate. 


How Do I Prevent Draughts From Double-Glazed Windows?

There are several fairly simple ways in which you can prevent draughts in the future. A little effort goes a long way: 

  • Quarterly Maintenance – Double or triple glazing windows don’t require a great deal of maintenance. A few times a year, ensure that you wipe down your windows and frames. This will allow you to spot minor cracks, failing sealants, or deteriorating weatherstripping.
  • Gentle Handling – Your windows have to be handled with some care. Ensure that you don’t slam or force them open. If you have issues opening the windows, try lubricating the joints. Nonetheless, gentle handling allows you to prevent damage to the hinges, locks and seals.
  • Professional Installation – You should always find the most reputable professionals for window installations, regardless of whether it’s a new window or a replacement. Good engineering and installation go a long way in terms of longevity. 



Overall, severe damage to double-glazed windows requires a professional to fix it. But these DIY solutions and future preventative measures go a long way in draught-proofing windows and keeping them in good condition. Bear in mind that some damage to double-glazed windows, such as seal failure, can result in the leaking of the insulating gas, and there is generally no way to fix this other than replacing the double glazed window unit.

Table of Contents

Click For A Free Quote