The Codman residence key is needed to enter the house without lockpicking. Upon entering, one will be in their living room which connects to the kitchen. Up the stairs to the right is a bedroom with a few containers and some mannequins. Up the next set of stairs to the third floor is a second smaller bedroom. As it is a house in the upper stands, the decor is nicer and neater than in the houses below.
The Codman residence appears only in Fallout 4.