Often when the subject of leaks is brought up in relation to EIFS, it's noted that the leaks are rarely if ever emanating from the EIFS itself, but more likely caused by improper application, installation or from finishing details like flashings or joints. Preventing the leaking from these finishing details, along with proper application and installation will result in flawless EIFS that doesn't run the risk of leaking.
Applying foam shapes
Foam shapes can be applied two ways. The first is to adhere the foam shape on top of the insulating foam, directly over the base coat. The base coat will prevent water from getting in where the foam shape meets the wall. The second, is to make the foam shape thicker than the wall itself, attach it to the substrate directly and have it emerge from within the EIFS wall. This creates an unprotected joint where water can get in, and the first option is the better choice of application for preventing leaks. The second method can be especially prone to leaks if the top of the shape is flat and smooth, because water will eventually pool there.
Applying these foam shapes also brings us back to the issue of mixing materials from different manufacturers, which can void warranties and result in wall components that are not compatible with each other. If foam shapes are to be used, the materials should be EIFS-oriented and from the same manufacturer.
Using expanded tape foam seals
Expanding foam tape can be used to create a hidden seal where an EIFS wall terminates at a window. Compared to wet-applied seals that rely only on bonding and adhesion to form an adequate seal, expanding foam tape seals by being strongly compressed into the gap, filling up any microscopic spaces. After the insulation is applied, the tape is placed in the gap where the insulation meets the window. The tape needs time to expand fully, but once this process is completed the lamina can then be applied over both the foam and the tape. For the expanded foam tape seal to be as effective as possible, the gap between the insulation and the window should be constant in depth as well as width.
If this method is used, be sure that it's somehow relayed to the owner of the building or home in question. Because it's hidden, an inspection may question whether the EIFS is properly sealed at the window or not.
Leaks and flashings
Typically, a flashing at the top of a vertical wall will prevent water from getting into anywhere that it's not supposed to. However if there's an aesthetic reveal in the wall, this groove can leave a space where the water can indeed get in, which can be considered a path of least resistance for the water as it gets directed into the groove easily by wind and rain.
One of the better and easiest ways for rectifying this issue is by not continuing the aesthetic reveal at the flashing, or stopping the groove before it gets there. The water will have no way to get in under the flashing this way as the groove does not direct it under the flashing. Other solutions for these problems can include extra caulking, depending on the size of the groove and how this may eventually look, aesthetically speaking.
Window flashings are another story entirely, particularly the ends of any window flashing that might direct any water runoff into the EIFS wall. Modifying the flashing ends so it routes water away from instead of into the wall can help solve this problem. Window flashings can also experience the same issues previously mentioned, or water getting under the flashing itself because of high winds or rain. The flashing must be installed in a manner where it can pick up water from window leaks and reroute it safely, as well as be caulked enough to not allow water underneath. If water leaks from the windows, drainage must be incorporated within the caulking to allow it to leave the window frame, where it then also must be rerouted.
The process of edge wrapping effectively seals the EIFS and prevents water from infiltrating the layers where it meets the sheathing. Edge wrapping is the process of bringing the base coat over the insulation and then bonding it to the opening. This seals the EIFS at wherever it terminates and keeps any water out. It also helps remove any spaces or gaps by closing the edges to the wall. This method is not compatible with drainage EIFS as the edge wrapping would stop up the drainage area, and common sense should be exercised with determining when and where edge wrapping might prove useful.