A private garage, Group U, shall be separated from a one-story dwelling unit, Group R-3, by means of how thick gypsum board?

In the context of building codes, the separation requirements between different occupancy types are designed to minimize fire hazards and ensure safety. Gypsum board is commonly used as a fire-resistant material to create barriers between areas with different uses within a building.

For a private garage classified as Group U and adjacent to a one-story dwelling unit classified as Group R-3, the International Building Code specifies that a certain thickness of gypsum board is required to create a fire-resistive barrier. The correct thickness in this case is typically 1/2 inch, which is sufficient to meet the fire protection standards established for these specific occupancy groups.

The choice of 1/2 inch thickness aligns with the code's intention to provide adequate separation while not imposing excessive construction costs. Gypsum board of this thickness is recognized for its ability to provide the level of fire resistance necessary to protect the dwelling unit from potential hazards originating in the garage.

In contrast, the other thickness options are greater than what is required for this particular scenario. While thicker gypsum board may offer even more fire resistance, it is not necessary or mandated for the separation between a garage and a dwelling unit based on the current codes. This is why 1/2 inch is the appropriate choice for this situation.