What should be put in the walls if fixture boxes cannot be installed immediately?

When fixture boxes cannot be installed immediately, blockouts are used in the walls to allow for proper placement and support of the fixtures at a later stage. Blockouts create openings in the wall structure that are specifically designed to accommodate the boxes once they are ready to be installed. This ensures that the location and alignment of the fixtures are preserved, maintaining the integrity of the overall installation process.

Using blockouts helps to prevent issues that may arise from trying to install the boxes later without predefined spaces, which could lead to complications such as misalignment or structural integrity problems. The incorporation of blockouts allows for a streamlined workflow, enabling other construction tasks to continue while awaiting the installation of the fixture boxes.

In contrast, the other options — expanders, reinforcements, and anchors — serve different purposes within construction and installation contexts. While they may contribute to overall structural stability, they do not specifically address the need for pre-prepared openings in the walls where fixture boxes would be placed later.