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Masonry Detailing Series

01.030.0301: Base of Wall Detail - Flexible Flashing, Drip Edge, Term Bar

DESCRIPTION / NARRATIVE

Detailing Series 01.030.0300 illustrates base of wall flashing systems for a 4” brick masonry veneer wall with 2” rigid insulation and 8” CMU back. This wall is also referred to as a 16” cavity wall or drainage wall.

Details 01.030.0301 and 01.030.0301.2D (Flexible Flashing, Drip Edge, Termination Bar):

A membrane or composite flashing installed with a metal drip edge at the exterior veneer offers superior water infiltration protection. Drip edges are beneficial at the base of a wall as they direct water away from the wall, prevent rising damp or stains from grade, and help resist water penetration at the joint (Figure 1). The metal drip edge should be at least 3” in depth and the drip is usually hemmed to about ½” long, and bent at a 30 or 45 degree angle (Figure 2). The flashing drip edge should be sealed and adhered to the foundation and the membrane flashing must be sealed and adhered to the drip edge. Use compatible sealant beads or mastics. The membrane flashing should be held back at ½” to ¾” from the face of the brick when using a flashing material that is not heat-stable (will drool) (Figure 3). Heat-stable membrane flashings are available.

Some membrane flashings are not UV resistant. In this detail a termination bar is used to secure the flashing to the CMU back up wall. Termination bars allow flashing to be installed just prior to the veneer, reducing the time of exposure. (Figure 4). By using a termination bar there is no interference with joint reinforcing and ties in the second course of CMU backup. The termination bar can be sealed at the top with a sealant joint or set in mastic (Figures 5 & 6).

The air/moisture/vapor barrier is usually installed before the flashing, although sequences may vary. If the AMV is installed first, the flashing and termination bar cover the air barrier and are sealed to the air barrier. If the flashing and termination bar are installed first, the flashing can be lifted and the AMV applied. This sequence is not required, as the termination bar /flashing connection is an approved connection system. The AMV can also be lapped over the flashing (Figure 7). Compatible sealants and mastics must be used.

A mortar dropping collection device (MDCD) is not used in this detail.

To get the whole picture for your project, contact IMI: 800-IMI-0988 or techresources@imiweb.org.

INFORMATION / DISCLAIMER: It is recommended to use all components of the Masonry Detailing Series (Description, 3D Detail, 2D Detail, Pictures/Figures and References) when using these details. We also encourage users to contact IMI Staff at 1-800-IMI-0988.

These details are intended for the use of industry professionals who are competent to evaluate the significance and limitations of the information provided herein. This publication should not be used as the sole guide for masonry design and construction, and IMI disclaims any and all legal responsibility for the consequences of applying the information.

It is important to note that details and construction practices vary based on geographical requirements and area practice. Masonry walls and elements must be adapted for each specific project. There are many typical details and practices, however, designers and contractors need to coordinate each detail with the unique elements of the building.