Bathroom Design

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Bathroom Design

Principles to keep in mind when designing your next bathroom

Posted on Sep 22 2017 by Martin Holladay

Americans who grew up in the 1950s or early 60s (that includes me) remember living in a house with one bathroom. There was usually someone standing outside the door yelling, “Hurry up!”

These days, most Americans live in (or aspire to live in) a house with two or more bathrooms. My guess is that we’re never going to return to the bathroom standards of the 1950s; two-bathroom houses are probably here to stay.

If you’re designing a green home, you know that a guiding principle of green design is, “Small homes have a lower environmental impact than big homes.” It's a good idea to keep that principle in mind when you decide (a) how many bathrooms your home needs, and (b) how big each bathroom should be.

You may need fewer bathrooms than you think. Many families will find it easy to live in a house with one full bathroom and one half bathroom (that is, a room with a toilet and a lavatory).

In praise of the small bathroom

For me, the main reason that small bathrooms make so much sense is that bathrooms need to be cleaned regularly. Smaller bathrooms are easier to clean.

Which rooms deserve extra square feet? I believe that the rooms where we spend the most hours per day — usually the kitchen and the living room — should be spacious and delightful. On the other hand, the rooms where we don’t spend much time — the bathroom and closets — should be as small as possible. (Bedrooms, too, should be as small as possible, because most of the time that we spend there, we are unconscious.)

A short vocabulary lesson

In the house I grew up in, everyone in the family brushed their teeth at “the bathroom sink.” These days, there is no such thing as “the bathroom sink.”

Plumbing supply houses only use the word “sink” for kitchen sinks. (Don’t ask why; that’s just the way it is.)

Bathroom sinks are now called “lavatories.” That’s confusing, for two reasons: (1) In most of the world, “lavatory” means “bathroom,” and (2) In the U.K., a lavatory is a toilet.

It seems to me that “bathroom sink” is less confusing. But it’s too late to untangle this mess.

The cabinet under a lavatory is called a “vanity.” (Of course, “vanity” has other meanings, including “dressing table,” “handbag for toiletries,” and “inflated pride” — but we won’t go there.)

In the plumbing trade, toilets are usually called toilets. Most toilets come in two sections, the tank and the bowl. Like “vanity,” “toilet” has other meanings, including “bathroom,” “the routine of combing one’s hair and putting on makeup,” and “dressing table.” But it’s time to move on.

The 5x8 bathroom

In the old days, residential designers learned that standard bathroom fixtures could be fit into a room measuring 5 by 8 feet. (It should be noted that a standard bathtub is 5 feet long by about 30 or 32 inches wide.)

There are several ways to fit a bathtub, toilet, and lavatory into a room measuring 5 by 8 feet. Of course, if the bathroom is larger, it’s easier to get creative.

Needless to say, a 5 by 8 foot bathroom won't be accessible for people who use wheelchairs. If wheelchair access is important, plan accordingly.

Tub, shower, or tub/shower unit?

I like bathtubs. Families with children certainly need a bathtub for the kids.

Almost every family wants to have a shower, so a tub/shower unit make a lot of sense.

If your house has plenty of room, you may want to design a master bathroom that includes a shower that is separate from the bathtub. (For those who prefer showers, a shower stall is more convenient to step into than a tub/shower unit.) Alternatively, if your house will have two full bathrooms, you might want to design one bathroom to have a tub/shower unit, and the other bathroom to have a shower stall.

And if someone in your family uses a wheelchair, you’ll want to include a curbless roll-in shower.

Plan for a drainwater heat-recovery device

In most homes, there is one bathroom where most showers occur. You should plan to install a drainwater heat-recovery device under this bathroom. That takes planning; it will only work if there is a basement under the bathroom, or if the bathroom is on the second floor.

For more information, see Drainwater Heat Recovery Can Lower Your HERS Score.

Keep your hot water pipes short

Ideally, your bathroom or bathrooms will be close to your kitchen (either vertically close or horizontally close), and your water heater will be located in a mechanical room or basement location that allows for very short piping runs (see Image #2, below).

Long hot water pipes waste water and waste energy. For more information on this issue, see All About Water Heaters.

Framing details

Remember to include framing details that accommodate plumbing requirements. You'll need a 2x6 partition behind the toilet to handle the 4-inch vent stack, and you'll need to make sure that there aren't any floor joists directly under the toilet.

Even if you have no plans to install grab bars near the toilet, tub, or shower, it's a good idea to provide blocking at the framing stage for possible future grab bars.


Some bathrooms have an operable window; if yours does, that’s good. Whether or not your bathroom has an operable window, every bathroom needs to have a dedicated exhaust fan or a grille connected to the exhaust duct of a heat-recovery ventilator.

For more information on this important topic, see these two articles:

Include good lighting

Many bathrooms are dimly lit. Include good lighting to the right and the left of the mirror above the lavatory, as well as good lighting above the tub/shower unit and good ambient lighting for the entire room.

For more information, see Martin’s 10 Rules of Lighting.

Sensible finishes for the walls and floor

The ’70s are over, so most people know that it isn’t a good idea to install carpeting or hardwood flooring in a bathroom. Common flooring choices are ceramic tile, linoleum, vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). tile, or sheet vinyl. (Most green builders avoid the use of vinyl flooring, for reasons explained in an article titled Vinyl Windows and Vinyl Siding.)

Does your floor need electric-resistance heating cables? Maybe. Since the area of the typical bathroom floor is small, this luxury isn’t as much of an energy hog as you might think. Moreover, if your home is heated by ductless minisplits, it never hurts to have some electric resistance heat available for the coldest nights of the year.

Wall areas that are likely to get wet deserve ceramic tile, while wall areas that are likely to stay dry can get ordinary drywall, moisture-resistant drywall, or plaster.

If your bathroom includes a combination tub/shower, you can either purchase a one-piece fiberglass tub/shower unit, or install a traditional cast-iron tub with ceramic tile on the walls. I'm a traditionalist, so I've always favored cast-iron tubs surrounded by tile.

Extra features

The bathroom of 2017 is very different from the bathroom of 1965. Many homeowners expect a master bathroom to have a nearby walk-in closet or closets.

These days, a master bathroom will often have two lavatories.

For those who focus more on function than luxury, it’s worth considering the idea of putting the washer and dryer in a bathroom. You may also want your bathroom to have an alcove or adjacent mechanical room for the water heater.

How important is it to make a statement?

If you are designing your dream home, you may be looking forward to a bathroom that makes visitors say “Wow.”

My own advice: dial it back. You won’t be spending much time there.

Martin Holladay’s previous blog: “Low-Income Housing: Problems and Solutions.”

Click here to follow Martin Holladay on Twitter.

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Image Credits:

  1. Image #2: Ann Edminster - San Joaquin County Habitat for Humanity

Sep 22, 2017 4:15 PM ET

The comments are elsewhere
by Martin Holladay

There are two (identical) versions of this blog. The one on this page is behind the paywall, as usual for my weekly Friday blog. The other is the "GBA Prime Sneak Peek" version, which is freely accessible to non-subscribers.

GBA readers have chosen to post their comments on the other version of this article. If you have a comment, it probably makes the most sense to post it on the other page, along with the rest of the comments. Here is the link: GBA Prime Sneak Peek: Bathroom Design.

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