Vertical Wall Flashing Over A Wall Control Joint

Waterproofing is often required over adjoining building components.A typical requirement is for the installation of vertical flashing over a construction joint in the vertical substrate. The issue at this location is to provide adequate waterproofing protection for the vertical component and the construction joint.

Waterproofing at the vertical construction joint is achieved through the application of a backer rod and the proper sealant. The backer rod is applied to control the depth of the sealant, which should be maintained at a 2:1 (width to depth) ratio. The type of sealant depends on the substrate material. Polyurethane is typically applied at masonry or concrete substrates.

The most important aspect of sealant application is joint preparation. The substrate must be free of all dust, dirt and contaminants prior to sealant application. Primer may or may not be required depending on the sealant manufacturers requirements. It may be beneficial to apply a butyl tape over the joint prior to the waterproofing membrane application. The waterproofing membrane manufacturer should be consulted to determine compatibility of the material over construction joints.

The vertical waterproofing flashing material is then applied to the substrate in accordance with the membrane manufacturers requirements. If this application involves a plaza deck construction, the flashing material should be set above the final topping (concrete, pavers, landscaping, etc.). A termination bar and metal counterflashing should be installed in a double blade saw-cut above the final surfacing line.

This detail provides for two points of waterproofing protection at these critical junctures. The additional waterproofing flashing is used to eliminate sole reliance on construction sealants, which would eventually become a maintenance issue. This detail also accounts for slight movement that may occur at construction joints and protects against sealant separation.

(Graphic courtesy of Paragon Roofing Technology Inc.)