Adding a bathroom to a finished basement greatly improves the livability of the space, though at first glance it appears to have gravity working against it. After all, in most basements the main drainpipe exiting the house is closer to the ceiling than to the slab below. Actually, this is an easy opportunity to triumph over client misgivings and Newton’s apple. There are two ways to connect a toilet to an existing overhead drain line: an in-floor ejector system or an above-floor system. The above-floor system uses a sealed pump tank, to which the bathroom fixture drains are connected. The tank can be concealed in an enclosure or closet, and requires little or no demolition of the concrete floor. On the down side, you’ll have to build a raised platform, about 6 inches high, to accommodate the waste pipe. This means that access to the toilet requires a step up. The platform may also impinge on headroom requirements.
I prefer the in-floor system, and customers are usually happier with it because it provides a normal appearance and easy access to the toilet. In one recent job, I converted a raised-platform toilet to an in-floor installation (see Figure 1).
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