If you have a ladder, use it to continue to stock your upstairs refuge. If not, catalog what you do have, fill all sinks and other receptacles with water, and prepare for a long wait. Stay out of sight. If you listen to the radio, do it at a minimum volume. When the skies darken, do not turn on the lights. Do not go near the windows. Try to make it seem as if the house has been abandoned. This may not stop a random zombie intrusion, but it will help to discourage a mass congregation from descending upon your home.