R303.4

Section R303.4 is titled 'Mechanical ventilation' and covers the requirements for providing mechanical ventilation in a dwelling. The air infiltration rate at a specified pressure, which invokes the requirement for a whole-house ventilation system, and a cross-reference to another section of this code for such system installation details is established. The purpose of this section is to assure a dwelling gets adequate ventilation for the health and comfort of the occupants as well as to prevent mold growth and premature degradation of building elements.

The model shows a dwelling with a whole-house ventilation system being installed. (The roof and ceiling are being hidden to provide visual clarity).