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Avoid Leaks in Drainage Planes

Leaks in Drainage Planes – No laughing matter!

One of the costliest callbacks a builder will ever experience is a callback involving concealed water intrusion and the resulting damage. Many builders invest considerable dollars to eliminate these callbacks with the specification of proven exterior wall drainage plane materials, yet the success of drainage planes requires attention to detail and follow-through to win the war against water intrusion. A properly installed drainage plane will mitigate potential losses and allow us to rely on the manufacturer’s warranty. Create a complete drainage plane game plan.

A drainage plane game plan should include:

  • A plan specific plan review to address problematic areas and transitions between materials before installation

  • Manufacturer based training of installers

  • Staying with one manufacturer’s products within the same assembly when possible unless written approval is obtained from all manufacturers involved

  • Proper installation of products verified by a third-party inspector

The effectiveness of even the best weather-resistant sheathing, flashing and drainage plane products can be compromised if all elements of a game plan are not followed.

Plans should be reviewed by a qualified party to identify problematic areas and insure that proper detail is provided for installers of windows, doors and flashings. This eliminates guesswork and establishes the standard by which the installation is to occur. Without clear details, critical decisions are often made by installers in the field whose level of concern for complete and correct installation is not as intense as that of the builder.

Rely on the manufacturer’s installation instructions to educate field staff and installers with regard to “what to do and what not to do” and to guide the installer through the installation process. It is not uncommon for trained installers to forget critical steps and for manufacturers to periodically make changes to product installation and introduce new products, consequently there is no substitute for familiarizing all parties with current installation requirements. The value to the builder in being familiar with these will help identify installation defects as they occur, before mistakes are repeated.

Use a complete system to take full advantage of the manufacturer’s warranty. When products from multiple manufacturers are mixed in the same assembly without written approval, the products may not be chemically compatible, and finger pointing is likely to ensue if a leak develops. If multiple flashing or drainage plane products are used in the same assembly, it may not be clear which product is failed if a leak develops. The value of a complete system from a single manufacturer is that these issues are avoided.

Specify to all trades which products they may use to repair the annular space around penetrations and any damage that may occur during the rough-in stage of construction. Installers and other trades who make repairs to drainage planes often substitute materials on hand for the correct brand and type of flashing tape. Burgess encounters a wide variety of tapes which are used to repair drainage plane penetrations, many of which are improper.

Think of exterior wall drainage planes as a two-part system in the sense that openings in the wall such as doors, windows and penetrations should be flashed independently and not rely on housewrap and housewrap seem tape for window flashing. A common misconception is that housewrap alone can be substituted for window and door flashing. Please refer to the manufacturer’s installation requirements for clarification.

Timing is everything when it comes to drainage planes and flashing sequence. Because we build homes with constant gravity, we should always use gravity to our advantage and lap flashings and drainage plane products in a weatherboard fashion. Doing so allows horizontal adhesive flashings to establish an uninterrupted bond to the substrate at the point where it is most critical. Sound simple? Generally it is, but it requires more thought than is often afforded by installers and the result is improper lap.

Make the bond between self-adhesive flashing tapes and the substrate. A common defect that we encounter when performing drainage plane inspections is flashing tape and joint or seem tape that is simply not bonded to the surface to which it is applied. Several self-adhesive flashing tapes require rolling as some adhesives are pressure sensitive and rely on the forces exerted by a roller to establish the required bond.

For more information or to discuss your particular project, please contact your local Burgess Division office or Roger Casey, Executive Vice President at

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