How to Install Spacer Blocks for Ceiling SupportFrom: diynetwork.com
These steps will walk you through the process of adding wood
blocking between joists in the attic to resolve a recurring ceiling crack below.
Step 1: Clear the Area BelowClear the workspace and cover the furniture and floor in the room below with a drop cloth.
Step 2: Measure Under the InsulationIn the attic, roll the insulation back just so that it's out of the way. Later you'll roll the insulation back into place. Measure the space between the joists.
When working in a hot attic, make sure to drink plenty of water and take frequent breaks. It also helps to work early in the morning when the temperature isn't as high.