A window track is not just a groove the sash slides in. On most aluminium sliding windows and doors it is a drainage channel, designed to catch water that gets past the seal and take it outside through small weep holes at the bottom of the outer frame.
Fill that channel with dirt and the drainage stops, and water goes where it was not meant to.
What goes wrong
Water backs up into the room. The most common symptom, and it is misdiagnosed constantly. Water appearing on the floor inside after driving rain is usually blocked weep holes, not a failed seal or a leaking window. People replace seals and the problem continues.
Water sits in the track. Standing water against aluminium with dirt in it accelerates corrosion, which matters most on the coast.
The window gets hard to open. Grit in the track wears the rollers and the track surface. Rollers are cheap; a worn track is not.
Mould. A permanently damp track with organic debris in it grows mould that then spreads to the seals and the surrounding reveal.
Insects. Blocked weep holes and damp debris are a breeding site.
Where the salt sits
In coastal Sydney the track is where salt and sand accumulate and never get washed away by rain, because the track is sheltered by the sash above it.
That is the classic corrosion position — covered in powder-coated aluminium in a salt zone. Pitting starts in the track long before it shows on the visible frame.
For anyone within a few hundred metres of surf, flushing the tracks with fresh water every few months is genuinely worthwhile maintenance.
Cleaning them
- Vacuum first. A crevice tool gets most of the loose material. Doing this before any water turns dust into mud you then have to dig out.
- Loosen the compacted layer. A stiff brush, an old toothbrush for the corners, or a flathead screwdriver wrapped in a cloth for the hard-packed material in the channel base.
- Vacuum again.
- Clear the weep holes. This is the step that matters most and is almost always missed. Find the small slots on the outside face of the bottom rail and clear each one — a thin piece of wire, a pipe cleaner, or compressed air. Then pour a cup of water into the track and watch that it drains out.
- Wash the track with warm soapy water and a cloth or sponge.
- Dry it.
- Lubricate if needed — a dry silicone spray on the track. Not oil or grease, which attract dirt and make the problem worse.
Do it with the flyscreens out, since both jobs are easier at once — see how to clean flyscreens.
What not to do
No pressure washer. It drives water past the seals and into the wall cavity, which is the problem you are trying to prevent. The same principle as weep holes and subfloor vents elsewhere on the building — openings that exist for drainage must never be targeted.
No chlorine bleach on aluminium tracks. It is corrosive to aluminium and the track is already the most vulnerable part of the frame.
No abrasives. Scouring the anodised or powder-coated surface removes the protective layer and corrosion follows.
No oil-based lubricants. They collect grit and form a paste.
Sills
The external sill below the window does its own job: it is shaped to throw water clear of the wall below, usually with a drip groove on the underside.
Debris or paint build-up on the sill, or a blocked drip groove, lets water run back against the wall instead of dripping free. Over years that is a damp line down the render or the brickwork, and on older walls it feeds the salt problems described in efflorescence on brick.
Worth a look while you are at the track.
How often
Twice a year for most houses. Quarterly on the coast or anywhere dusty.
The weep hole check is the part worth doing on schedule rather than after a leak. It takes a minute per window and it prevents the single most common cause of water appearing inside during a storm.
If a window has been leaking and you are about to call a glazier, clear the weep holes first. It is free and it resolves it surprisingly often.
For tracks, screens and glass together, see window cleaning.
