Unfinished Bonus Room . A major factor when determining the cost of your renovation is going to the size of your bonus room. House plans with unfinished rooms, or as they are sometimes called, bonus rooms, are spaces called out on the blueprints of a house plan that have no designated function. 503 Southern Wood Unfinished Bonus Room TRINITY BUILT HOMES from www.trinitybuilthomes.com First and foremost, it’s extra space, even if it doesn’t count as a bedroom because it lacks those roomlike features. Transform a bonus room to reflect your lifestyle and activities. This is the way to go.