For SFRM application, substrate temperatures must be maintained at ___ for ___ after application.

The correct choice emphasizes the importance of maintaining the substrate temperature at a minimum of 40 degrees Fahrenheit for a period of 24 hours after the application of Spray-Applied Fire-Resistive Material (SFRM). This temperature and duration are critical for ensuring the proper curing and adhesion of the fireproofing material, which can greatly influence its performance.

Maintaining the substrate temperature within this range allows the SFRM to properly bond to the surface, reducing the risk of delamination or poor coverage, which can compromise fire resistance effectiveness. Additionally, a consistent temperature can prevent issues such as trapping moisture in the material, which may lead to deterioration or a reduction in fire protection capabilities.

Understanding the specific parameters for temperature and time is paramount for adherence to industry standards and ensuring the long-term performance of SFRM in providing the necessary fire protection.