The recommended depth for attic insulation is usually 10 14 inches.
Insulation for water pipes in attic.
For other homes the pipes might be located in the walls or the roof rafters.
Insulation will help maintain water temperature levels in the pipes.
Shop pipe insulation here.
The drywall ceiling was insulated and the pipe was separately insulated even further as i say 360 degrees.
Water inside the pipes can still freeze.
Process for weatherizing pipes in exposed areas of the home such as the garage basement and exterior walls.
Ref insulate cold water pipes thoughtfully the frozen pipe was in the attic of the garage.
Otherwise a cold water line run a long distance through a hot attic can take several.
For some homes the pipes will run underneath a subfloor or at the bottom of the attic.
While pex does not ordinarily burst in the cold the water in the pipes can still freeze.