Water Supply Systems
Water supply delivers potable water at adequate pressure. Minimum service pipe size is 3/4 inch, with 1 inch recommended for larger homes. Copper pipe Type M is suitable for interior applications at pressures up to 200 psi. PEX tubing has become popular due to flexibility, corrosion resistance, and lower cost.
Drainage and Waste Systems
Drainage removes wastewater by gravity. Pipe sizes are based on fixture unit loads. A toilet has a DFU of 3 to 6, while a lavatory has a DFU of 1. Minimum slope for 3 inch pipe is 1/4 inch per foot. truss geometry and member sizes. corner bead protects outside corners. Proper slope maintains self-cleaning velocity.
Venting Requirements
The vent system prevents trap seal loss by allowing air into the drainage system. Each fixture trap must be protected by a vent connecting to the main stack through the roof. house wrap with drainage channels. Wet venting allows one fixture’s waste pipe to serve as another’s vent under specific conditions.