Drainage on a patio has a lot of variables, if doing a permeable patio, you want the water to go down through the joints to soak into the subsoil and into the underground aquifer. If it is a standard patio, often the best way, if elevations permit, is to get the water to flow off the patio into the areas surrounding. There are often cases where neither of these are permitted, and channeling water into a drain is necessary. The Quick-E-Adjustable drain is the easiest drain on the planet to set in place and adjust perfectly, plus it looks great and is offered in a plastic or stainless top.
Retaining walls always require drainage, perforated pipe pitched to one location where it can then be day lighted out through the front of the wall is necessary. Another crucial requirement is that the water must be displaced by 8” from the base of the wall. This is to prevent saturation at the toe of the wall, which can lead to failures. Pave Tools’ Retaining Wall Spillway is the perfect build for this application and incorporates a built-in spillway, displacing the weeping water beyond the toe of the wall.