No. 3: Improper Flashing and Drainage Planes for Water Management

Sometimes it seems like builders have forgotten some old-fashioned techniques when it comes to water and moisture management and, too often, I see them make the same mistakes when it comes to flashing and drainage planes. Today’s construction is more complicated than before. New materials and techniques make new homes less forgiving, and if they’re subjected to extended wetting cycles and are unable to dry, they are likely to fail.

This means we need to pay very careful attention to how windows are flashed, how penetrations are sealed, and whether water coming off the roof is winding up in the basement or crawl space. There is little room for flexibility here. To avoid problems, you need to pan-flash all windows and doors in every climate. You need to flash all penetrations at the sheathing interface, integrating them with a weather-resistive barrier. You must make sure kick flashing, gutters, and complex connections between walls and roofs, deck ledgers, and other challenging design features are flashed and drained with the technology of old: slopes, shingling, and intentional paths for water.

Take the extra time to get it right. Work with your framers, roofers, siding contractors, plumbers, electricians, and other trades to define how the building will be flashed and the water will be managed, who will do the work, and what techniques they will use. Use a high-quality, nonperforated housewrap. Choose compatible tapes and sealants. Select subs who understand the issues and whom you can trust to ensure that all these pieces and parts work together.