CONTROLLING MOISTURE: DEFLECTION CHECKLIST

Deflection is the first principle and main priority of water management. Some of the primary strategies that have proven effective at reducing the amount of rainwater on exterior walls include the following:

• Place the building so it is sheltered from prevailing winds by other buildings, trees, etc.
• Use a pitched roof where appropriate.
• Provide sizable roof overhangs and water collection systems at the roof perimeters.
• Provide architectural detailing, including flashing and caulking to direct rainwater away from the building.
• Provide an approved drainage system around the foundation perimeter to accept roof water run-off.
• Install a weather barrier within the wall in an appropriate location and with vapor permeability appropriate for the climate and moisture management approach.
• Install permeable bulk vapor diffusion retarders on the exterior of walls and floors, including below a concrete slab or on top of the bare soil within a crawl space.
• Separate wood elements from moisture sources including soil and concrete, using impermeable membranes.

Source: Design of Wood Frame Structures for Permanence, American Wood Council