In blueprints, what does the notation "42" AFF" represent?

The notation "42" AFF" stands for "42 inches above finished floor." This indicates a specific mounting height for an object, such as an outlet, switch, or other fixture, that is to be installed at this height relative to the finished floor of the space. The use of "AFF" is common in architectural and construction blueprints to ensure that items are installed at the correct height for usability and accessibility.

In the context of blueprints, knowing the mounting height is essential for various reasons, including compliance with building codes, ensuring user comfort, and maintaining aesthetic alignment within a space. Therefore, the notation clearly communicates important installation information to contractors and builders, aligning with the requirement to have consistent and measurable details in the project documents.