Abstract: A dam member is positioned adjacent the junction of an upstanding wall and a floor in a building structure. The dam member is trapezoidal in cross-section with a base surface attached to the floor with sealant means and an inner side surface facing the wall and tapered away from the wall from the base surface to a parallel top surface. A cap member is removably positioned between the wall and the dam member inner surface and is spaced above the floor to define an enclosed channel with the dam member, the wall and the floor. The cap member is trapezoidal in cross-section with an outer side surface tapering away from the wall from a bottom surface to a parallel top surface, the cap member outer side surface cooperating with the dam member inner side surface to enclose the channel. A plurality of dam members and cap members are positioned end-to-end about the periphery of the floor to direct water leaking through the wall-floor junction to a central drain for removal from the building.