Window cleaning: what it covers and what it costs

Almost every quote for window cleaning splits into interior and exterior, and the reason is safety rather than pricing.

Interior glass is a straightforward job done from the floor or a small step. It is priced per window and slots into an ordinary house clean.

Exterior glass above ground level needs water-fed poles, ladders or a platform, plus the training and insurance that go with working at height.

That is a different service with different equipment, so it is quoted on the building rather than added to a domestic booking. A quote that does not separate the two has usually only priced one of them.

Glass is the visible part and the smallest part of the work.

• Glass on both faces where access allows, finished without streaks or edges left wet.

• Frames wiped, including the underside of the top rail where dust collects.

• Tracks vacuumed and then wiped, rather than smeared with a damp cloth.

• Sills cleaned, inside and out.

• Flyscreens removed, brushed or washed, dried and refitted.

Tracks and screens are what separate a real window clean from a wipe of the glass. They are also the two an agent looks at during an exit inspection.

Almost nobody uses spray and paper towel, and the reasons are worth borrowing at home.

The glass is wetted generously with a soapy applicator, which lifts the grime rather than moving it. A squeegee then removes the water in overlapping strokes, and the blade is wiped between each one.

Edges are detailed last with a dry microfibre cloth. Most streaks are simply water that ran back down after the squeegee passed.

Working in shade matters more than any product. On hot glass the solution dries before the squeegee reaches it, and that is what leaves the smears people blame on the cleaner.

Exterior work above the ground floor is now mostly done with water-fed poles, which reach three storeys from the ground and remove the ladder entirely.

The water is purified first, so it carries no dissolved minerals. Glass is scrubbed with a brush on the pole head and then rinsed.

It is deliberately left to dry on its own. Pure water leaves nothing behind, so there is nothing to dry off, and a cloth would only reintroduce what was removed.

If the exterior of your windows is left running wet, that is the method working rather than an unfinished job.

Interior work has a minimum charge almost everywhere, so a handful of windows costs much the same as a dozen.

Tracks and flyscreens are sometimes included and sometimes extra. It is the most common difference between two quotes that look the same.

Interior windows are available as an extra on our regular and one-off cleans, which is the cheapest way to have them done if a clean is already booked.

Twice a year suits most homes. Once before summer and once after winter keeps glass from ever reaching the state where it needs real work.

Coastal properties need it more often. Salt is abrasive and, left long enough, etches glass in a way no amount of cleaning reverses.

The same is true near construction sites, where cement dust settles and then sets. That one is genuinely urgent rather than cosmetic.

Offices and shopfronts are usually monthly or fortnightly, because the glass is part of how the business presents itself rather than part of the building.

Flyscreens are the item most often assumed and least often included, so it is worth asking directly.

A screen that has not been washed in years holds a surprising amount of dust, and it undoes clean glass the first time the wind blows.

Screens are unclipped, brushed or hosed, dried and refitted. Older aluminium frames can be brittle, and a screen that breaks on removal usually needed replacing anyway.

Tracks need vacuuming before anything wet touches them. A track wiped while dry-grit is still in it turns to paste, which then dries into the corners.

Sills, the underside of the top rail, and the frame around the hinge are the other three places a quick job skips. All of them show in photographs.

Overcast and still is the ideal day. Direct sun dries the solution before it can be removed, and wind puts dust straight back onto wet glass.

Rain, contrary to the joke, does not undo a clean. Clean glass sheds water without marking; it is dust already on the pane that rain turns into streaks.

Spring is the busiest season, so book a fortnight ahead if the timing matters. Autumn is quieter and the glass is usually in worse condition, which makes it better value.

For apartments, check the strata rules before booking. Some buildings require exterior work to be done by their own contractor, and finding that out on the day wastes everybody's morning.

A few well-meant shortcuts cause damage that no window cleaning can undo.

Scrapers and blades on tempered glass leave fine scratches. Shower screens and balustrades are the usual casualties, and the marks only appear in direct light.

Abrasive pads and household scouring cream do the same thing more slowly.

Pressure washers force water past seals into the frame and, on older double glazing, into the cavity, where it fogs permanently.

And sprinklers that hit windows for months leave mineral deposits that bond to the surface. Adjusting the sprinkler is the fix; cleaning is not.

The white spotting on glass near a sprinkler, a pool or the coast is mineral rather than dirt, and ordinary window cleaning does nothing to it.

Caught early it lifts with an acidic glass cleaner and a little patience. Left for years it bonds into the surface, and at that point the glass is etched rather than dirty.

The test is simple. Wet the pane and look again: if the marks vanish while wet and return as it dries, they are still on the surface and can be removed.

The permanent version needs a cerium oxide polish, which is a restoration job rather than a clean, and it is priced accordingly. Fixing whatever is spraying the glass is cheaper than doing it twice.

Shower screens are the same problem indoors. A squeegee after each use does more than any product sold to fix it later.

Clear the sills and move furniture back from the glass. A cleaner needs about a metre in front of each window.

Take down blinds you want cleaned behind, and say which curtains can be moved and which cannot.

Unlock any gates and secure dogs. Access to the side and rear of a property is the most common reason an exterior job comes back unfinished.

Mention windows that are painted shut or have failed locks. A cleaner will not force a window, and knowing in advance keeps it off the quote.

Interior glass is the half worth attempting, and the method above works at home with about thirty dollars of equipment.

A squeegee, a microfibre applicator, a bucket and a drop of dish soap will outperform any spray bottle in the supermarket aisle.

Vacuum the tracks before wetting anything. Wet grit in a track turns into a paste that takes longer to remove than it did to create.

Leave the outside above ground level to somebody insured to be up there. That is the part of window cleaning where the equipment is genuinely the job.

Work one room at a time and finish each pane before moving on. Half-done glass in six rooms is the usual result of an ambitious Saturday, and it looks worse than not starting.

Do the insides yourself twice a year, and book the outsides once. That split keeps the cost down without ever letting the glass reach the state that needs real work.