Secret Room

A secret room is at least a decent place to hide from zombies due to the room already being hidden and can easily be overlooked if the house is poorly examined some houses that belonged to people who have a lot of money will put up a secret room for themselves the entrance to the secret room is hidden in plain sight

An entrance to the secret room be sure to examine the house enough to notice something about the wall.

(such as being a bookshelf part of the wall a door with no handle being painted the same color as the wall etc.) and can be used to hide in if you do not have the tools and supplies to fortify the house you can use the secret room as a starting point to securing a house if you have found at least one.

Advantages

The room is already hidden in plain sight and can easily be overlooked by bandits if they raid the house.

It is a starting point for securing the house if said room is big enough.

The room may have been used as a bachelor pad with the room and drinks for supplies to be stored and a couple other survivors.

Disadvantages

The entrance to the door may fail to open from the inside.

Usually not much space for supplies and survivors.

Requires extensive planning ahead of time.

Usually expensive

Rare and difficult to find

Same issues as bank vaults