What size and type of gypsum board is required to separate a garage from a habitable room above it?

The requirement for a specific thickness and type of gypsum board to separate a garage from a habitable room above it is primarily based on fire safety regulations. The correct choice is 5/8" Type X gypsum board, which is specifically designed to provide increased fire resistance compared to regular gypsum board.

Type X gypsum board has additives that enhance its fire-resistant properties, allowing it to withstand high temperatures for an extended period compared to standard drywall. This is critical in situations where a garage, which may house flammable materials and vehicles, directly underlies living spaces. Building codes typically stipulate that areas such as these require fire-rated separations to help prevent the spread of fire from the garage to the residential areas above.

Using 5/8" Type X gypsum board helps ensure compliance with local building codes, which are focused on protecting the occupants of the habitable space from potential hazards associated with the garage. Additionally, the thickness of the board further contributes to its durability and performance under fire conditions.

While other options may also offer various benefits such as soundproofing or additional insulation, they do not meet the specific fire safety requirements that Type X gypsum board does for the scenario described.