Figure 2 shows two pipes, where the waterproofing detail is successfully executed at both. In Figure 7, the two pipes are right next to each other, violating Guideline #1 - Spacing. The waterproofing installer attempted to waterproof two penetrations as one single penetration without sealing the gap between the two pipes. Considering the environmental exposure of below-grade waterproofing is subject to water submersion, one cannot expect watertight performance when the waterproofing seal is missing between the two pipes. The solution that will provide a reliable seal is to relocate one of the pipes to provide clearance between the two pipes. Therefore, it is good practice to establish a minimum clear spacing between penetrations, such as 6 inches minimum clear spacing. Once the minimum clear spacing requirement is established during the project's design phase, contractors are more likely to coordinate clear spacing between trades, report if penetrations must be spaced closer together, and allow the waterproofing installer an opportunity to review and effectively execute the detail.
A photo of a unique penetration consisting of a small concrete pedestal form with a round concrete forming tube supporting an electrical junction box is presented in Figure 8. As photographed, the waterproofing membrane is installed to the conduit and the concrete forming tube per the "by-the-book" penetration details. The seal to the concrete forming tube is incorrect. The concrete forming tube is made up of cardboard. Cardboard is not watertight, sound, or solid and thus deviates from Guidelines #2 and #3 and is not a suitable penetration to interface with the waterproofing seal. A common strategy for a penetration that deviates from Guidelines #2 and #3 is to switch the seal to a suitably watertight solid material. The junction box itself is metal and thus satisfies Guideline #3 - Sound and Solid. However, the junction box perimeter has numerous knock-outs for possible conduit connections. Knock-outs are discontinuities in the metal of the junction box. Discontinuous in the metal means the junction box is not watertight, deviating from Guideline #2 - Watertight. As neither the concrete forming tube nor the junction box are suitable waterproofing substrates, only the concrete pedestal remains. Concrete is porous, prone to cracking, and does not generally have watertight performance in a below-grade environment. There are no suitable penetration materials in Figure 8 because all the elements deviate from Guideline #2 - Watertight. One strategy is to switch the non-watertight materials to watertight materials, as in the below-grade grounding rod example. However, for the example shown in Figure 8, the best strategy is to avoid the penetration altogether. The penetration from the concrete pedestal can be completely avoided by running the waterproofing membrane continuously. In other words, use the concrete pedestal as a substrate for the waterproofing membrane by turning the waterproofing membrane vertically around the pedestal and then pass it between the concrete pedestal and the junction box, resulting in no penetration through the waterproofing membrane.
Below-grade waterproofing requires the penetrations to meet the three general guidelines without exception for a reliably successful seal. When irregularly shaped penetrations occur, the waterproofing solutions can be found by diagnosing how the penetration deviates from the three general guidelines and finding the solution that avoids the penetration altogether or modifies it to comply with all three general guidelines.