The water control layer (commonly referred to as the weather barrier) protects the exterior part of the wall assembly from the effects of bulk water that moves by gravity and wind pressure. It prevents the infiltration of water, and protects building components from water damage caused by weather conditions such as; rain or snow.

The water control layer protects your wall cavity from OUTSIDE elements.

The water barrier prevents the infiltration of water carried by gravity or rain/snow driven by wind, through the control layer. Above grade exterior water tries to enter the building envelope by gravity, capillary action, and pressure differences. The water control layer is engineered to prevent water penetration from occurring. It is also designed to allow the wall assembly to dry out when it gets wet.

It is important to note that flashings form a very important part of the water control layer. Flashings are used to direct bulk water out of the wall system and away from the building and work in partnership with the weather barrier system.

Criteria:

• Installed towards the exterior
• Resistant to air flow
• Able to shed rain or snow
• Able to withstand the forces (weather) that may act upon it
• Durable during construction and over expected building life

Materials:

• Building papers
• House wraps
• Sealed rigid board insulations

Placement/Location:

Installed behind the exterior façade (usually siding or brick), these materials are fastened to the exterior wall using staples, plastic washer nails, and/or special approved tape(s). Not all products can use all fasteners so it is important to ensure the appropriate method for each product is followed.

If a water control layer is not installed properly or fails it can cause serious repercussions for the building materials within the building envelope. When water enters a building envelope, it can have a dramatic impact on insulation materials within the cavities as the thermal effectiveness of the materials can be greatly reduced if they become damp or wet. Other issues that may arise within the envelope are rotting wood, mould and mildew, and structural damage from deteriorating materials.