Residential Building Inspector B1Building Planning and Life SafetyEasy
A residential building inspector is reviewing plans for a new single-family dwelling that includes an attached garage. What is the minimum required thickness for gypsum board applied to the garage side of a wall separating the garage from the dwelling unit?
- A1/4 inch
- B5/8 inch
- C1/2 inch
- D3/8 inch
Show answer & explanationAnswer & explanation
Correct answer: C. 1/2 inch
The IRC specifies a minimum 1/2-inch gypsum board thickness for walls separating a garage from the dwelling unit to provide adequate fire resistance. This is a common and critical fire safety requirement.
Why the other options are wrong
- A. 1/4-inch gypsum board is typically not sufficient for fire-rated assemblies between a garage and dwelling.
- B. 5/8-inch gypsum board, while offering higher fire resistance, is not the minimum required in this specific application by the IRC.
- D. 3/8-inch gypsum board is not the minimum specified for fire separation between a garage and dwelling.
Garage-Dwelling Fire Separation Wall
A wall separating an attached garage from a dwelling unit must have a minimum fire-resistance rating to prevent the spread of fire. The IRC specifies materials and construction for this separation.
- Required for attached garages.
- Minimum 1/2-inch gypsum board on garage side.
- Ceilings also require fire separation if habitable space above.
Memory trick: Guard the Garage, Gypsum is Great!