Securing your shelter in the zombie-infested world of Project Zomboid requires more than just finding a suitable location. This guide details how to effectively barricade windows, a crucial step in fortifying your base.
How to Barricade Windows in Project Zomboid

To board up windows, gather the necessary materials: one wooden plank, a hammer, and four nails. Once you have these items in your inventory, right-click the target window. Your character will automatically begin securing the plank. Each window supports up to four planks for enhanced protection.
Hammers and nails are commonly found in toolboxes, garages, sheds, closets, and similar locations. Planks are frequently located on construction sites, or can be salvaged by dismantling wooden furniture (shelves, chairs, etc.). Administrators can utilize the "/additem" command to spawn items.

Barricaded windows significantly hinder zombie entry. The more planks installed, the greater the resistance. To remove planks, right-click the boards and select "Remove." A claw hammer or crowbar is required for this action.
Note that large furniture items (bookshelves, refrigerators) cannot be used as effective barricades; players and zombies will pass through them. However, knowing how to move furniture remains a useful skill for interior arrangement.
More robust barricades can be constructed using metal bars or sheets, but this requires sufficient Metalworking skill.