Yes, you should plan on being home when a window cleaner is cleaning your windows. The professional will clean both sides of the glass and will likely disassemble parts of your windows from the inside to clean and inspect the inner components, including the balances and weatherstripping. Much of this work requires interior access to your home, which means someone will need to be home to provide access to the window cleaner.

Professional window cleaners typically use either a white vinegar solution or a commercial hard water stain remover to clean hard water stains on windows. A common vinegar solution for this purpose consists of one cup of white vinegar mixed with a gallon of distilled or bottled water. The pro will spray the mixture and lightly scrub the window with a scrubby pad before cleaning with a standard cleaning solution. Alternatively, they may use a commercially available hard water stain remover and a scrubby pad, followed by a complete cleaning.

Whether you tip before or after a carpet cleaning depends on when you’re available. If you’re home when they finish up, you can give them their tip after. However, if you need to leave before they’re done or if you won’t be home at all, you can prepare the tip beforehand and leave it for them in an envelope.

Mold on windows forms due to excess moisture from condensation, poor ventilation, or leaks. Cold glass surfaces can attract condensation, especially in winter. High indoor humidity, lack of airflow, or dust accumulation are also contributors. To prevent mold growth, improve ventilation, regularly clean sills, and consider using a dehumidifier or sealing any leaks.