Protect a Home From Mildew

Understand that the terms mold and mildew are used interchangeably although it is generally accepted that mildew is always the visible, colonized form of fungus whereas mold can be the spores floating in the air or the visible form.

Avoid moisture in your home. To do this keep rooms well ventilated, open windows and doors when possible on a daily basis to allow the fresh air to blow through.

Use a vapor barrier in walls. This is standard building code in most areas. A vapor barrier is a polyethylene (clear plastic) sheet that goes between the drywall and the insulation of the home. It helps keep moisture from condensation and from getting into the walls.

Use an exhaust system. Bathrooms and kitchens need to have an exhaust system to blow steam from showers and cooking out of the house. This can be a problem in older homes that weren't built with ventilation systems like bathroom and over the stove hood fans. If you can't have them installed, make it a household policy to open the window after a shower or while cooking until the steam is off the windows.

Avoid closing curtains on a steamy window as this creates a pocket where moisture can sit and mold spores can germinate. The same goes with furniture: try to leave a space between furniture and walls so air can circulate.

Use a dehumidifier. This is the most expensive preventative measure, but it works. Dehumidifiers actively pull moisture from the air. Make sure the appliance is working in a closed area as there's no point in trying to dehumidify the whole street.