The addition of rooms to one or more of the sides of a house will not have an adverse effect on the performance of either the addition or the original structure; however, the two separate foundations will be prone to differential settlement with respect to each other. The addition of rooms as a second, third, or higher floor of a structure may adversely affect the performance of the original building's foundation. If it is desired that an additional floor be added, tests and inspections should be made to evaluate the foundation, the soil, and the structure of the original building before continuing with construction.