Controlling Moisture and Avoiding Mortar Infill Behind Brick Veneer

Relevant Standards

Requirements for spaces behind brick veneer are covered under several sections of the Michigan Residential Code:

• Section 703.7.4.2 - Air Space (note that weather-resistant membranes are now required under the 2003 Amendment to the Michigan Residential Code)
• Section R703.2 and Table R703.4 - Weather-resistive barriers
• Section R703.7.5 - Flashing (required beneath the first course of masonry and above finished ground level)
• Section R703.7.6- Weep holes (note that some builders are now placing weep holes both at the base and at the top of the wall, which allows for improved air circulation)
• Section R703.8- Flashing material and location requirements

During the frame and masonry inspection (R109.1.4), officials should verify that the following are installed according to manufacturer's installation instructions where applicable:

• Weather resistant sheathing paper
• Flashing
• Weep holes (must be at least 3/16-inch in diameter, located immediately above the base flashing)

The use of a product designed to avoid mortar infill behind brick veneer is not required by Michigan Residential Code, but helps builders better meet code requirements to keep the cavity and weep holes open. Residential HouseNet™ by MortarNet^® is a good example of this type of product.