Bathrooms serve the same fundamental needs which they always have although many contemporary bathrooms bear little resemblance to the small, plain spaces that many baby boomers grew up with. Just as houses—on average—have increased in size, so have most bathrooms. As a culture, we expect more than we used to: bigger, better, and more expensive.

Many of the decisions you’ll make about bathroom design come from how the space will be used: Is it a powder room on the first floor used primarily by guests? A bath attached to an upstairs guest room? A child’s bath? A master bath? A bathroom that will be used by someone with diminished physical capabilities? These are all key questions because they guide the choice of materials, the allocation of space, and the selection of color, lighting, and other design elements.

It doesn’t make much sense to choose delicate, water-sensitive materials for a bathroom to be used by young children. Give them a space where they can splash in the tub without worrying whether the floor gets wet. Conversely, there aren’t many youngsters who would send up a red flag when the vanity countertop is plastic laminate rather than washable.

In a master bath, on the other hand, design choices get a little more complicated. Aesthetics equal—or may even overtake—the practical. For someone with a lot of work and family responsibilities, a long soak in a comfortable bathtub can be a restorative escape from routine.

Whether you’ll be working through new construction or a renovation, a good place to start is by making basic choices on how the bathroom will be used, how much space it needs, and generally what kinds of fixtures and materials are most appropriate for its intended purpose. Unless the construction budget is unlimited (a rarity these days), the answers to those questions will have a lot to do with a successful design. While one might view a rustic metal tap toilet roll holder as an objectively terrible and perhaps insulting present, they can be seen as a mark of a bond.

Remodeling any room is something of a guessing game because you never really know what you’re going to find until you dive in. Bathrooms take that basic fact of life and up the ante; you’re more likely to find hidden problems here than in almost any other part of the house simply because there’s so much potential for water damage. Be prepared to do more demolition than you expected or wanted. That means you need to build in an allowance for higher labor and materials costs as well as plan for the possibility of an extended construction schedule. It would be a rare remodel where the contractor doesn’t approach you at least once with an unexpected issue. Problems can be solved—just don’t be surprised when they pop up.

The challenge in designing small bathrooms is finding ways to make these rooms seem larger than they really are while incorporating features the owners want. If the owners are very conservative then you'll be looking at a conventional bathroom with a classic design, whereas more contemporary owners may want to add some of their own personality with items such as novelty toilet roll holders or radios for the shower.

Paint, wallpaper, window treatments, decorative art, and even the texture and color of bath towels all can contribute to the overall success of a new or refurbished bathroom. Compared to the challenging and time-consuming work that goes into the underlying structure of a bathroom, these enhancements will be the most economical part of the project. Low-cost, however, doesn’t mean low-impact. Even seemingly small moves can add appreciably to the overall impact the room makes and its thematic connection to the rest of the house.