In accordance with one embodiment, a method is disclosed including cutting an opening in a sidewall of a bathtub and providing an overlay to cover the bathtub. The overlay can include an assistance feature such a tread, door, or capsule.

Embodiments described herein include a bathtub that can include a U-shaped step saddle associated with a door assembly. The door assembly can include a hinge coupled with the U-shaped step saddle such that the door assembly can be transitioned between an open position and a closed position. The door assembly can include a catch and a latch to secure the door in the closed position.

Proposed is a bathtub base plate having a structure facilitating mounting of a bathtub. The bathtub base plate may be conveniently fitted to the bathtub so that the mounting time may be reduced, a bottom of the bathtub is capable of being mounted inclinedly since an upper surface of the bathtub base plate has a gradient, and a function of reducing a resonant sound may be provided by placing a space between the bathtub and a bathroom floor. Since a double structure in which the bathtub base plate and the bottom surface of the bathtub are in close contact with each other is provided, a strength reinforcement function and the function of reducing the resonant sound may be provided. A border rib and a bathtub reinforcement rib formed on the bottom surface of the bathtub are capable of being fitted to a fitting groove of the bathtub base plate body.

Proposed is a bathtub base plate having a structure facilitating mounting of a bathtub. The bathtub base plate may be conveniently fitted to the bathtub so that the mounting time may be reduced, a bottom of the bathtub is capable of being mounted inclinedly since an upper surface of the bathtub base plate has a gradient, and a function of reducing a resonant sound may be provided by placing a space between the bathtub and a bathroom floor. Since a double structure in which the bathtub base plate and the bottom surface of the bathtub are in close contact with each other is provided, a strength reinforcement function and the function of reducing the resonant sound may be provided. A border rib and a bathtub reinforcement rib formed on the bottom surface of the bathtub are capable of being fitted to a fitting groove of the bathtub base plate body.