The possibility in Pompeii of the housing in the so-called "Insula" which we can find in Ostia is dealt with in this paper. Pompeii provides the evidence of upper floors. However these floors were constructed secondary and we can find a case of the house three storied. All the measurable walls were approximately 40 centimetres, which were too thin to support multistoried floors. A few houses are regarded as Insula in the limited sense that they were constructed simultaneously, and that the housing was controlled under the principles of construction of upper floors.
