Controlling Moisture and Avoiding Mortar Infill Behind Brick Veneer

Introduction

When properly installed, brick veneer provides a durable and aesthetically pleasing exterior surface. To reduce the incidence of efflorescence, moisture and mold behind brick, the Michigan Residential Code requires that veneer be separated from the wall sheathing by an air space.

This cavity is designed to allow water that does get in behind the veneer to drain down and out of the weep holes. It also allows air movement and eliminates pressure differentials that force moisture into the cavity and behind the veneer.

However, during construction, excess mortar drops into the wall cavity where it can clog weep holes and prevent water from exiting the inside of the wall. Serious moisture problems can result.

For proper brick veneer installation, the following are required:

• A weather resistant barrier properly adhered to the wall sheathing
• An air space of at least one inch but not more than 4.5 inches that allows ventilation of the cavity
• Flashing, including base flashing
• Weep holes spaced no more than 33-inches on center (most manufacturers and brick associations recommend 24-inches on center)

While not yet required by code, mortar collection devices are available to catch excess mortar droppings and prevent them from filling the cavity and clogging the weep holes. This allows the space to drain and ventilate properly, which reduces moisture and mold incidence. The products are designed to ensure that masonry walls breathe, drain and dry quickly.

Since the cavity can be quite narrow, it is possible for the fallen mortar to "bridge" the complete width of opening. Therefore for a mortar collection device to be effective, it must break up and suspend the mortar droppings at two or more heights - thus assuring that water can find a way to flow to the weep holes.

* * *

	To watch the video, your computer must have up-to-date video viewing software installed. If the video doesn't work, you need to download the FREE Windows Media Player by clicking HERE.