Is window film worth using?

Interior film kits add a temporary sealed air layer and can help noticeably in a cold climate for a single season. They are a stopgap rather than a repair.

Can a foggy double glazed unit be fixed?

In many cases the sealed glass unit can be replaced while keeping the frame, which is cheaper than a whole window. Ask whether that is an option for your window before quoting a full replacement.

Maintenance

How to find air leaks around your windows

Straightforward ways to locate draughts around windows and doors, which fixes are homeowner work, and when the leak is really a sign of a failing window.

By Elijah Canfield, Founder, Hire Best Pros · Updated August 26, 2026

Elijah Canfield is the founder of Hire Best Pros. He writes and edits the site's consumer guides, with a focus on how home service and moving projects are priced, scoped and compared.

Two installers fitting a replacement window into the opening of a house

Find leaks on a cold or windy day by feeling along the sash, the frame edge and the trim, or by watching a thin strip of tissue or the flame of a candle move. Look for daylight around a closed sash, condensation between panes, and gaps in caulking. Weatherstripping and caulking fix most small leaks. Failed seals, rot and warped sashes are a repair or replacement conversation.

How to check

Run a hand slowly around the sash and frame on a cold, windy day
Hold a thin strip of tissue near the edges and watch for movement
Look for daylight around a closed and locked sash
Inspect caulking outside and weatherstripping inside for gaps and cracking
Check for condensation between the panes, which indicates a failed seal

Fixes within reach

Replace worn weatherstripping on the sash and jamb
Recaulk the exterior joint between the frame and the siding or brick
Seal interior gaps behind trim where they are accessible
Add a door sweep on exterior doors while you are working through the house
Confirm locks engage properly, since a lock pulls a sash tight against the seal

Draughts that sealing will not fix?

Find window help

Signs the window itself is the problem

Fogging or moisture trapped between panes
Sashes that no longer close square or lock properly
Soft, rotted or crumbling frame and sill material
Cracked glazing or hardware that has failed

While you are at it

Windows are rarely the largest source of air leakage in a house. Attic hatches, recessed lighting, plumbing and wiring penetrations and the rim joist often move more air. If comfort is the goal rather than just the window, it is worth checking those at the same time.

Common questions

Is window film worth using?: Interior film kits add a temporary sealed air layer and can help noticeably in a cold climate for a single season. They are a stopgap rather than a repair.
Can a foggy double glazed unit be fixed?: In many cases the sealed glass unit can be replaced while keeping the frame, which is cheaper than a whole window. Ask whether that is an option for your window before quoting a full replacement.