When building owners and roofing professionals provide weatherproofing for piping through roof decks, pipes that penetrate roof systems often are not grouped in single locations, creating the need for multiple locations of penetration flashings, such as site-fabricated flashings and pitch pockets. However, this is not NRCA's preferred method and results in an excessive number of roof system penetrations (see "Penetration pockets," April issue, page 62).
Instead, NRCA recommends a method that leads to reduction of penetrations. Building owners and roofing professionals should be aware of a seldom-used method of providing weatherproofing for piping through roof decks: a curb and sheet-metal enclosure.
The NRCA Roofing and Waterproofing Manual, Fifth Edition, includes Detail TS-16, "Sheet Metal Enclosure for Piping Through Roof Deck." The detail provides a method of reducing multiple site-fabricated flashings and/or pitch pockets by grouping several pipes in a single location, reducing the overall number of penetrations through the roof membrane. To improve weatherproofing, the vertical pipes are turned horizontally and exit the side of the sheet-metal cover at a slight downward angle to reduce the possibility of water penetration.