Building a Sunken Cement Bath

Placement

• Selecting the placement of a sunken cement bath is the first challenge with building it. Second-floor bathrooms, such as an upper-level master bath, can't accommodate sunken cement baths without special alterations to the rest of the home's design. This is because the bath is deeper than the thickness of the floor so its structure extends into the ceiling of the room below. The same holds true for a sunken cement bath on a first floor when it is located above a basement. Sunken cement baths can be located over closets or storage spaces that have low ceilings or over parts of the home that don't have living space below them.

Framing

• Building a sunken cement bath begins with a structural frame that will support the bath. This frame attaches to the floor joists and, in some applications, adjacent wall studs to provide enough strength for the weight of the sunken bath. The frame can be made of timber or, in the case of first-story and patio baths, dug into the earth and formed from compacted sand. The frame must also accommodate the plumbing, including the bath's drain.

Pouring Cement

• Once the frame and plumbing are in place, the sunken cement bath is ready for pouring. A wood form must be built to keep the cement in place as it dries. Once it does, a liner can be installed to make the bath watertight. If the bath's base is flat, it must be built with a slope so that water runs to the drain. Sloping the base with a flat piece of wood and a hand level, while the cement is still wet, is the best way to achieve the desired shape.

Prefabricated Forms

• Another option for building a sunken cement bath is a precast cement form. These forms are constructed from wood, cement and fiberglass and can be inserted into framed openings, thereby removing the need to pour a cement bath. However, cement forms are heavy and difficult to move into place, especially if they're being added to an existing bathroom as part of a remodel.