It's one of the most common questions homeowners ask when booking a house wash: "Will you do the windows too?" The honest answer is nuanced. High-pressure water and residential windows are a bad combination, but that doesn't mean your glass has to stay dirty. Here's what can go wrong, what professionals actually do around windows, and the right way to get exterior glass clean.
Why High Pressure and Windows Don't Mix
Residential window glass is tempered for impact resistance, not for a concentrated 2,000+ PSI water stream at close range. Direct pressure washing of windows risks several failure modes, most of which don't show up until days or weeks later:
- Cracked or shattered glass — especially older single-pane windows and any glass with existing chips or stress fractures
- Blown seals on double-pane (insulated) units — pressure forces water past the perimeter seal, causing permanent fogging between panes that can't be cleaned
- Flooded window tracks and weep holes — water driven into the frame drains into wall cavities instead of back outside
- Stripped glazing and caulk — the flexible seals around window frames deteriorate quickly under direct pressure
- Damaged screens — even moderate pressure stretches and tears fiberglass screen material
What Professional Washers Actually Do Around Windows
A competent house-washing crew doesn't avoid windows — they change technique. During a soft wash, the cleaning solution is applied to siding and windows alike at garden-hose pressure, allowed to dwell, then rinsed top-down. The detergent that cleans your siding also breaks down the film on your glass.
The result: windows come out noticeably cleaner than they started, because the same organic film, pollen, and oxidation on your siding is also on your glass. What a soft wash won't deliver is squeegee-finished, streak-free glass — rinse water dries with mineral spotting, especially in hard-water areas.
If you want truly spotless glass, ask whether the company offers a window cleaning add-on. Many washing companies carry water-fed pole systems with deionized (DI) water — purified water dries without spots, no squeegee needed. Expect to pay $4–$12 per pane as an add-on, which is typically 20–40% cheaper than hiring a separate window cleaner for a standalone visit.
DIY: Getting Exterior Glass Clean Safely
If you're washing your own house exterior, treat windows as a rinse-only zone. Keep the wand at least 4–5 feet back, use a wide fan tip (40°), and never linger on the glass. Then finish windows separately with the right tools:
- Wash with a soft-bristle brush or strip applicator and a squirt of dish soap in a bucket of water
- Squeegee top to bottom, wiping the blade between passes — this is what eliminates streaks, not the soap
- For second-story windows, a water-fed pole with a DI filter beats ladder work on both safety and results
- Avoid cleaning glass in direct midday sun — solution dries before you can squeegee it, guaranteeing streaks
- Never use razor blades on tempered glass or any glass with a tint film or low-E coating
When Windows Signal a Bigger Problem
Sometimes dirty-looking windows aren't dirty at all. Permanent haze or fog between double panes means the insulated seal has already failed — no amount of washing fixes it, and the unit needs replacement. Etched or rainbow-hued staining near sprinkler zones is hard-water mineral etching, which requires polishing compounds or professional restoration rather than washing.
If your windows fog between panes shortly after any washing (pressure or soft), the seals were already marginal — washing exposed the failure rather than caused it. It's worth photographing window condition before any exterior cleaning job so there's a clear before/after record.
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