A curbless shower base includes a subbase structure having a sloped floor and a zero entry. At least one side wall can be mounted flush with drywall during an installation so that a tile or other wall covering is installed flush over the at least one side wall to a floor of the subbase structure A drainage channel in the subbase structure extends substantially from a first side of the subbase structure to an opposite second side of the subbase structure. The drainage channel is sloped from the first side of the subbase structure to a drain outlet in the drainage channel, and the drainage channel is sloped from the second side of the subbase structure to the drain outlet in the drainage channel. A drain assembly has a drain outlet to connect with plumbing during the installation. A protective structure of the drain assembly at least partially surrounds the drain outlet.