Prev NEXT  


A Guide to Bathroom Design

Bathroom Layout Imperatives

This layout conserves budget and time by lining plumbing against one wall.

The typical 537-foot bath "footprint" makes a generously sized powder room and a decent-size half bath. It can be sufficient for a kids' bath if no more than two will be using it at once and if you've cleverly planned in separate storage for each child. It may even be enough for a master bath if what you most want is just the convenience of the plumbing in or near the master bedroom.

A 537-foot space won't be enough, however, for a lavish master bath with extra fixtures (bidet, separate whirlpool tub, sauna, etc.), and it may also be a bit skimpy for a shared family bath by today's standards.


You can make up the difference visually by keeping the design scheme calm, using mirrors liberally, and specifying cabinetry that makes the best use of space (consider lazy Susans; cubbyholes; and small drawers, such as lingerie or spice drawers).

But to really add space, you'll need to see if you can steal a few feet from an adjacent closet or unused area of a neighboring room or hallway, or even bump out a mini-addition. In most rooms, another 18 inches wouldn't mean much, but they can make a surprising difference in the bath!

Where to Put the Bath?

It's a bigger challenge to install a new bath in an existing home than to remodel a bath or to build a bath into a new house. That's because "back-of-the-wall" plumbing and mechanical requirements have to be installed within an existing wall, and you won't know what that involves until the wall is opened.

It's an even bigger challenge when you're installing the bath on an upper floor or in the basement. While a professional can make it work, you'll want to be aware of the issues.

­A basement bath requires special planning for below-grade plumbing. A space 16 square feet (30375 inches) is adequate for a toilet and a sink; to include a shower or a tub, you'll need a space about 35 square feet (537 feet, which is the size of a standard bathroom).

Building codes allow ceiling heights of 84 inches for basement baths, which is 6 inches lower than for other living areas. This variance will come in handy if your ceiling height is restricted by pipes or ductwork.

The most critical factor in installing a basement bathroom is locating drains and vent stacks. Getting hot and cold water to the space is a matter of splicing into existing supply lines, but pumping wastewater out may be more difficult.

All bathroom fixtures must drain into the main drain line, which is a 3- to 4-inch diameter pipe that enters the basement through the floor above and exits the basement through a wall or the floor.

Accessing the main drain for a new basement toilet may mean cutting through a concrete floor -- a difficult task. Also, new fixtures can only be located a limited distance from the existing drain line, and extensions to the line must slope down at the rate of at least 1/4 inch per foot.

In two-wall bathroom layouts, be sure to leave adequate space between bathroom fixtures.

If tying into existing lines below floor level is not practical, you'll need a sewage ejector -- an electric pump attached to a holding tank that pumps sewage up through a discharge pipe into the main house drain.

Sewage ejectors are fairly costly but not much more noisy than today's pressure-assist toilets. You'll also need to tie new drains to existing vent stacks or install a new stack, most often alongside the exterior of your house in an inconspicuous location.

A new upstairs bath must also tie into the existing main drain line and vent stack, but this is usually an easier accomplishment because upper floors and walls are not made of concrete. Not to mention, in upper floors, gravity works with, not against you in moving waste downward.

Regardless of where you plan to locate your new bath, you know installing it isn't for amateurs. Unless plumbing and mechanical engineering are your lines of work, consult the experts, and save your energy for choosing fixtures and decorative treatments!

Configured to save space, this bathroom features a three-wall layout.

Basic Bath Considerations

If you've ever wondered why many bathrooms are back-to-back or why professionals tell you to avoid moving fixtures, it's because of all the plumbing and mechanical systems you can't see.

"Back-of-the-wall" systems include various pipes to bring fresh water into the room, pipes to bring hot water from your hot-water heater, pipes to carry away wastewater, more pipes to carry away waste, vent stacks to keep pressure equalized and to prevent sewer gasses from entering the house, and on and on.

Even if your bath is on the third floor of your house, its systems have to route up to the roof and down to the systems buried in your lawn on the ground level. Bottom line: The fixtures are just the end point of an entire system.

If you really want to know about all this in detail, the information is available. If not, simply respect that the system is complex, and be aware that your installers not only need to solve whatever problems they encounter in your individual house, but they also need to solve it within the confines of rigorous building codes designed to safeguard your family's health and your home's safe function. Your understanding can help you get the best job possible from your installers.

If you're remodeling an existing bath, you'll have to decide whether you want to incur the expense of moving basic fixtures and changing the basic layout.

If you're only moving a fixture a few feet for a slightly better look, you may elect to go ahead -- or not, given the cost. If the existing bath layout really bothers you or is unworkable, your top priority may be to relocate fixtures.

What's important is that you understand that this is much more complex than, say, moving a king-size bed from one wall of your bedroom to another!

Virtually every bathroom uses one of the following three basic layouts:

  • One-wall layout. One-wall baths have the toilet, sink, and combination shower/tub plumbing aligned along one wall, making for a relatively long, narrow bathroom. One-wall layouts are often used where the simplest solution is to cut off the "end" of a long room and dedicate it to bath fixtures. This layout is also frequently used for powder room or half bath layouts. You may find extra fixtures, such as a bidet, a separate tub, and a separate shower in a one-wall bath, but it's not common.
  • Two-wall layout. Two-wall baths usually have the toilet and sink on one wall and the shower/tub combo (or separate shower and tub) on the other. You might also find the toilet and bidet on one wall and the shower/tub and the sink on the other, depending on the length of each wall. A two-wall layout offers a desirable sense of enclosure, but care must be taken to ensure that fixtures are placed far enough from each other and from the door for safety and comfortable use.
  • Three-wall layout. A three-wall layout, with the toilet on one wall, sink on another, and combination shower/tub on the third, is a space-conserving solution that can put every fixture within a step of the others. It's also the layout you're likely to see in a master bath with numerous extra fixtures such as a bidet, more than one sink, and a separate tub and shower. If you are remodeling an old bath and want to install a number of new upgrades, a room that's already plumbed in the three-wall layout may be the easiest to work with.

After you've decided how to layout your bathroom, the next step is to consider lighting and ventilation. On the next page, learn more about these bathroom essentials.

To learn more about decorating or remodeling your bathroom, visit: