How to Clean Exterior Windows: Tools, Techniques and What to Avoid

Exterior windows collect more than just dust. They face salt spray, bird fouling, oxidised metal run-off, mould, and UV-baked grime that bonds to the glass surface over time. Getting them clean — and keeping them clean — requires a different approach to interior windows, and the wrong technique on the wrong surface can cause permanent etching, seal damage, or frame corrosion you can’t undo.

This guide covers everything you need to know about how to clean exterior windows at home: the right tools, the correct method for common surface types, what to avoid, and the point at which the job should go to a professional.

What tools do you need to clean exterior windows?

Using the right tools makes the difference between streak-free glass and a surface that looks worse than when you started. Here is what to gather before you begin.

• Microfibre applicator or soft-bristle window scrubber: The safest option for applying your cleaning solution without scratching the glass.
• Professional squeegee (30 cm or 45 cm): A quality rubber-blade squeegee removes solution in one clean pass. Cheap rubber blades streak badly — worth spending $20–$30 on a Unger or Ettore blade.
• Two buckets: One for your cleaning solution, one for rinsing the squeegee between strokes.
• Mild detergent or specialist glass cleaner: A few drops of dish soap in warm water works well for most glass. Purpose-made window cleaning solutions are better on hard-water areas.
• Microfibre detail cloths: For wiping the squeegee blade and detailing the edges after squeegeeing.
• Extension pole: Essential for any window above shoulder height. Aluminium poles telescope to 3–5 metres, keeping your feet on the ground.
• Garden hose with a gentle spray nozzle: For pre-rinsing heavy soil before your solution goes on, and for post-rinsing if you are not squeegeeing.

What you do not need: newspaper (a common myth — modern ink smears), paper towels (they shed and leave residue), steel wool, abrasive scouring pads, or undiluted vinegar on tinted or coated glass.

How do you clean exterior windows step by step?

This method works for standard single-pane and double-glazed glass at ground and first-floor level. Always work in the shade or on an overcast day — direct sun dries the solution before you can squeegee it off, leaving streaks baked into the glass.

1. Pre-rinse with water. Use a garden hose to knock off loose dust, cobwebs, bird droppings, and surface grime before your cleaning solution goes on. This prevents scratching when you apply the scrubber. Let the water drain.
2. Mix your solution. A few drops of mild dish soap in a bucket of warm water is enough. Avoid hot water, which can cause thermal stress on double-glazed units in cold weather.
3. Wet the glass with the applicator. Work from top to bottom so dirty solution runs down onto unscrubbed glass, not back over cleaned sections. Apply light, even pressure — you are wetting and loosening, not scrubbing.
4. Squeegee off from the top. Start at the top corner, pull the squeegee horizontally across the pane, and angle the blade slightly downward on each stroke so water channels to the lower end. Overlap each stroke by 2–3 cm. After each pass, wipe the blade clean with your detail cloth.
5. Detail the edges. Use a damp microfibre cloth to wipe the frame border, catching any residual solution that the squeegee missed. Run a dry cloth along the window sill to catch drips.
6. Check from an angle. Stand to the side of the window and look across the glass surface at a shallow angle — streaks, smears, and missed spots show up clearly in raking light. Touch up with a lightly dampened cloth as needed.

What is the best cleaning solution for exterior windows?

For most residential exterior glass, a simple mix of warm water and a small amount of dish soap is effective and safe. The soap breaks surface tension, allowing the water to sheet off the glass cleanly rather than beading and leaving deposits.

Where mineral deposits or hard-water staining are a problem — common on Sydney properties near the coast or with bore water irrigation — a diluted white vinegar solution (1 part vinegar to 10 parts water) can help dissolve calcium build-up. Do not use straight vinegar on tinted glass, low-E coated glass, or aluminium frames. The acidity can strip protective coatings and corrode bare metal.

Commercial window cleaning concentrates (available from janitorial suppliers) are worth using if you are cleaning regularly — they are formulated to work with squeegee technique and rinse cleanly without soapy residue.

What professional window cleaners use on high-volume jobs is pure water delivered through a waterfed pole system. Pure water (with dissolved solids removed by reverse osmosis or deionisation) leaves zero mineral residue on the glass as it dries, producing a spot-free result without a squeegee. It is the standard method for commercial and strata buildings because it is safe, fast, and leaves nothing behind to re-attract dirt.

How do you clean different exterior surface types?

Not all exterior windows are the same. The glass type, frame material, and surrounding facade all affect how you should approach the clean.

Standard clear glass

The most forgiving surface to clean. The step-by-step method above applies directly. Avoid abrasive applicators and rinse well before scrubbing to prevent scratching from grit.

Tinted or Low-E coated glass

Tinted glass and glass with low-emissivity (low-E) coatings is common in newer residential and commercial buildings for thermal performance. These coatings are on the inner surface of the glass unit and are not directly exposed, but the outer surface can still be softer than standard float glass on some products. Avoid anything acidic, alkaline beyond pH 9, or abrasive. A neutral-pH window cleaning solution and a soft applicator is the only safe choice.

Double-glazed units (IGUs)

The outer pane of a double-glazed unit can be cleaned the same way as standard glass. What you need to be careful of is the seal around the perimeter of the unit. Directing water at high pressure into the frame joints, or using chemical solvents around the rubber seals, can degrade the sealant and cause the unit to fog between the panes — a failure that requires full IGU replacement to fix. Keep your cleaning solution away from the perimeter seals and never pressure wash IGUs at close range.

Aluminium frames

Aluminium window frames oxidise and pit over time, especially in coastal environments. When cleaning, avoid highly acidic or alkaline cleaners that accelerate corrosion. A mild detergent is safe. After cleaning the glass, wipe down aluminium frames with a damp cloth and dry them — leaving salt-laden moisture sitting on aluminium speeds up oxidation. For pitted or discoloured frames, a dedicated aluminium cleaner or a light polish restores surface appearance, but deeply oxidised frames may need professional treatment or replacement. Our guide on residential window maintenance for Sydney homeowners covers frame care in more detail.

Rendered or masonry facades around the windows

If your windows are set into a rendered facade, iron staining, efflorescence, or organic growth on the surrounding render can transfer back to freshly cleaned glass quickly. Cleaning the glass without addressing the facade is a short-term fix. The render itself needs a low-pressure soft wash or a specialist facade treatment — something Shimmer handles as part of a comprehensive facade cleaning service.

What should you avoid when cleaning exterior windows?

Some of the most common mistakes cause damage that cannot be reversed. Here is what to avoid.

• Pressure washing at close range: A pressure washer at 15–30 cm will strip window seals, force water behind frames, and can crack older or thermally stressed glass. If you want to use a pressure washer, keep the nozzle at least 1 metre away and use a wide fan tip at low pressure — or avoid glass entirely and stick to the frames and surrounding surfaces.
• Cleaning in direct sunlight: The solution dries before you can remove it, leaving streaks and mineral deposits baked onto the glass. Work in early morning or late afternoon, or wait for overcast conditions.
• Abrasive tools: Steel wool, scouring pads, and stiff brushes scratch glass, especially if there is any grit present. Once glass is scratched, it cannot be polished out with DIY products — it requires professional glass restoration or replacement.
• Dry wiping: Wiping dry glass with a cloth — even a microfibre — risks micro-scratching if there is any surface contamination. Always wet the glass before wiping.
• Undiluted chemicals: Bleach, undiluted vinegar, ammonia-based cleaners, and solvent-based products can strip coatings, pit frames, and cloud certain glass types. Dilute everything, and check product compatibility with your frame material before using.
• Skipping pre-rinse: Scrubbing a dusty or gritty window without pre-rinsing first drags particulate across the glass, which scratches. Pre-rinse is not optional.

When should you call a professional instead of doing it yourself?

DIY window cleaning is practical for ground-level windows on residential properties. The calculation changes quickly in these situations.

• Any window above the first floor. Ladders account for a significant proportion of home injury hospitalisations in Australia each year. A professional with rope access certification, anchor points, or a reach-and-wash system does the job safely without putting anyone at risk. Our article on how to clean outside windows explains where the DIY line sits.
• Commercial, strata, or multi-tenancy properties. Buildings with common-area glass, high-volume facade surfaces, or strict OHS obligations need insured, certified professionals. Using untrained labour on common property is a liability risk.
• Specialised glass types. If your property has structural glass, frameless glass, heritage leadlight, or glass balustrades with specific manufacturer maintenance requirements, an experienced cleaner who works with those surfaces daily is far less likely to cause damage than a DIY approach.
• Post-construction clean. After building works, windows are often coated in silicone overspray, mortar splatter, paint, and adhesive residue that requires specialist removal products and technique. Trying to scrub this off with standard tools risks permanent scratching.
• When the glass has not been cleaned in a long time. Heavily soiled glass with mineral deposits, oxidised metal staining, or organic growth requires a multi-stage treatment — pre-treatment, dwell time, and careful removal. Aggressive scrubbing on this level of soiling without the right chemistry can damage the surface permanently.

Shimmer Glass and Pressure Cleaning handles all of the above across Sydney — from single-storey residential properties through to commercial and strata buildings. See what a professional window cleaning service includes and what to expect from a Shimmer visit.

How often should you clean exterior windows?

In Sydney’s climate, the general guidance is:

• Coastal and near-harbour properties: Every 6–8 weeks. Salt aerosol deposits on glass quickly and the combination of salt, moisture, and UV causes accelerated etching on unprotected glass.
• Inner city and suburban residential: Every 3–6 months for maintenance cleans, depending on tree coverage, dust levels, and local air quality.
• Commercial and strata: Typically monthly to quarterly depending on the building’s presentation standards, lease obligations, and foot traffic generating splatter at lower-level glass.

Regular cleaning at appropriate intervals is cheaper than remediation. Glass that is left uncleaned for years can develop etching, mineral bonding, and organic staining that requires restorative treatment costing significantly more than ongoing maintenance would have.