How do I clean outside windows?

Cleaning ground-floor and upstairs windows from outside safely, and when to pay someone instead.

Difficulty: intermediate
Time: 2 hr
Read: 2 min
Safety: caution

Short answer

Work on an overcast day, wash with a few drops of washing-up liquid in warm water, and squeegee top to bottom wiping the blade after each pass. For anything above ground floor, use an extendable water-fed pole from the ground rather than a ladder.

Outside windows are the same technique as inside, with two differences: far more dirt, and a real height risk. The technique is quick to learn; the judgement about what to attempt from a ladder is the part that matters.

Safety

Falls from ladders cause serious injuries every year. Never work from a ladder on soft or sloping ground, never overreach — move the ladder — and never lean a ladder against glass or a gutter. For upstairs windows, use a water-fed pole from the ground or pay a window cleaner. If you are in any doubt, do not go up.

What you'll need

Bucket
Washing-up liquid
Squeegee
Microfibre cloths
Extendable water-fed pole (optional)
Ladder with stabiliser (optional)

Step by step

Choose an overcast day or work in shade.In direct sun the water dries before you can squeegee it and streaks are guaranteed.
Brush cobwebs, leaves and grit off the frames and sills first.Grit dragged across glass by a squeegee scratches it.
Wash with a few drops of washing-up liquid in warm water.Barely soapy. More detergent means more residue to streak.
For ground-floor windows, wash and squeegee top to bottom, wiping the blade after every pass.A wet blade redeposits dirty water. This single habit fixes most streaking.
Run the squeegee across the bottom edge and dry the frame and sill.Water on the frame runs back down the glass as it dries.
For upstairs windows, use an extendable water-fed pole from the ground.Pure or filtered water dries spot-free, so these are designed to be left to dry without squeegeeing.
If you must use a ladder, foot it on firm level ground at about 75° and never lean it on the glass or gutter.One metre out for every four metres up. Have someone with you.
Clean the frames and any trickle vents while you are there.Blocked trickle vents are a common cause of condensation problems indoors.

Tips

Water-fed poles with a filter are the reason professional window cleaners no longer use ladders much. A domestic version is affordable and removes the risk entirely.
Twice a year is enough for most houses; more if you are near a road or the sea.
Do the insides on a different day. Trying to do both at once means you cannot tell which side a streak is on.

Common mistakes

Working in direct sunlight — The glass dries faster than you can squeegee, and streaks are unavoidable.
Leaning a ladder against the gutter or the glass — Both give way. Use a ladder stabiliser that bears on the wall.
Overreaching from a ladder — The most common cause of falls. Move the ladder instead.

Questions people ask

How do professional window cleaners get windows spot-free without drying them?

They use purified water, which contains no dissolved minerals, so it dries without leaving spots. Domestic water-fed poles with a filter cartridge work the same way.

Should I clean upstairs windows myself?

From the ground with a water-fed pole, yes. From a ladder, only if you are confident, the ground is firm and level, and someone else is present. Otherwise it is a cheap job to pay for and an expensive injury.