Look for the following plumbing problems in attics:
- Damaged plumbing vent pipes;
- Stack vents terminating in the attic.
- Plumbing vent slopes less than 1/4-inch per foot;
- Un-insulated water supply pipes;
- Plumbing stack 3" minimum diameter at roof (cold climate only); or
- Plumbing vent diameter reduction located less than 12" from sheathing (cold climate only).