Barricades can be used to improve the safety of your base. Barricading doors and windows will consume wooden planks and nails.
Barricading doors will control how quickly a zombie can destroy your door. A barricaded door will add 30 health to the door. A barricaded door usually lasts long enough so that you can escape from your house.
Barricading windows will prevent zombies from detecting you when you are inside your base. However, if you make any kind of sound (gunfire, sickness) zombies will notice you even if the windows are barricaded.