Why Can I Feel a Draught Around My Double-Glazed Window When It Is Closed?
For a closed double-glazed window that still lets in a noticeable cold draught around the sash, frame or surrounding seal, without the window being visibly open.
What this usually means
A draught from a closed double-glazed window usually means air is passing through a gap around the opening sash, seals, frame junction or installation perimeter. Everest describes air leakage around frames and weak seal points as a key part of window performance. A failed sealed glass unit causes insulation loss and may mist between panes, but a felt draught is more often about an air path around the frame or opening section.
What may be causing this
The opening-sash seals are not compressing evenly
Clues: The draught is strongest along one edge and changes when you press the closed sash gently toward the frame.
What to do: Have sash alignment, hinges, locking points and replaceable seals checked.
The perimeter seal between frame and wall has opened
Clues: Air is felt around the outer frame or reveal rather than the opening sash.
What to do: Inspect room-side sealant for visible gaps and have failed perimeter sealing repaired appropriately.
The frame or sash has distorted or become misaligned
Clues: The window is also stiff, catches, needs force to lock or has uneven gaps.
What to do: Arrange adjustment or repair rather than forcing the handle.
How to check what is happening
The local seal or sash compression is a likely air path.
Air may be bypassing the window through the installation joint.
Alignment or hardware problems may be preventing even sealing.
Can you fix this yourself?
Room-side checks can narrow the air path. Cleaning accessible seals and removing debris is reasonable, but adjustment, gasket replacement or frame sealing should be done without compromising drainage slots or the locking system.
- Torch
- Tissue strip for locating gentle air movement
- Soft cloth
What you can safely try
- 1
Clean the accessible seals and frame
Dirt or trapped debris can stop a sash closing consistently against its seals.
- 2
Inspect the room-side perimeter seal
Look for obvious cracks or gaps where the frame meets the plaster or trim.
- 3
Check whether the sash closes and locks normally
A stiff or misaligned window often needs hardware adjustment rather than extra sealant.
Call a window fitter if…
- The window cannot be locked securely.
- The sash is visibly distorted or loose.
- There is water ingress as well as the draught.
- The problem is on an upper-storey exterior side that cannot be checked safely.
- Seals or hardware need dismantling to diagnose the fault.
Get the right window fitter.
We already know this problem maps primarily to a window fitter. Choose the closest type of work, add your postcode and continue in the form.
Sources used for this guide
We prefer primary UK guidance, regulators and manufacturers for technical and safety-sensitive claims.
Last reviewed: 2 September 2026. Home Manual updates review dates only when the substance of a guide is checked or changed.