Bulk Water Control

Focus on the most destructive risk: bulk water. Cover shedding, drainage planes, flashing, sequencing, and transitions where failures concentrate.

Builds on: P6 (four control layers)  ·  Leads to: P8 (air/vapor), P9 (heat flow), P10 (assemblies)  ·  Cross-series: A7 Alternative Construction

P/A bridge: For panelized/modular systems, who verifies water-control continuity at transport joints, module seams, and site-set interfaces?

Core Concepts

• Bulk water causes fast, severe damage. Can prioritize detailing and sequencing that prevent wetting.
• Pathways and exits matter more than "waterproof everything." Can design for drainage and drying, not trapped water.
• Transitions concentrate risk. Can treat roof-to-wall and openings as primary design targets.

The Water Control Chain

Condition - Load - Mechanism - Failure mode - Control. Each link is a place where design and execution either manage the risk or pass it downstream.

• Precipitation (B2b): The source. Exposure and orientation determine how much water the building sees.
• Bulk water load (C3a): Roof geometry and runoff concentration turn rain into specific volumes at specific locations. Loads concentrate at geometry changes.
• Moisture mechanisms (E2c): Water enters through gravity failures, capillary action, wind pressure, kinetic energy. Sealant is not a mechanism - overlap, drainage, and pressure management stop water.
• Envelope failures (F3): Rot, mold, staining, structural damage. They cluster at transitions, not field areas.
• Water control (G4): Primary shedding + secondary drainage plane + flashings + drying path. Sequencing is part of the control.

Where Things Go Wrong