Stucco is also known as ‘Portland cement plaster’. It is generally used in building repair, to repair leaky windows, decorate exteriors or for any other decorative purposes. Restoration companies use it for restoration projects as it is widely available in various textures and colors.
To create holes, use a brace and bit to drill through the flooring, and then a keyhole saw to widen the entrance. Make sure that the holes are not exactly above a floor joist when you drill them. In fact, the joists & studying must be spared as much as possible while installing the water heater equipment.