Bathroom Design

Designing a bathroom, particularly when working with existing spaces on a remodeling job, is often a matter of making the most from as little room as possible. A standard layout can be a good starting point (see Small Bathroom Layouts, below), but may need to be adapted to fit a particular space. For any layout, follow the guidelines in this section for eliminating obstacles and integrating fixtures for maximum usability and efficiency.

Entrances and walkways. Start with a clear walkway at least 32 in. wide at all entrances to the bathroom (Figure A)

Figure A: Bathroom Doors


Draw the swing of all doors — entrance, closet, shower, and cabinet — on plans to ensure that there are no conflicts. Optimally, entrance doors should be at least 32 in. wide.
Draw the swing of all doors — entrance, closet, shower, and cabinet — on plans to ensure that there are no conflicts. Optimally, entrance doors should be at least 32 in. wide.

On plans, draw the swing of all doors to ensure that none of them intersect with each other.

Lighting is critical in bathrooms — both general lighting and task lighting. General recommendations are presented in Figure B

Figure B: Bathroom Lighting Rules of Thumb

Electrical. Specify ground-fault circuit interrupters (GFCIs) on all receptacles. No switches should be within 60 in. of any water source. All light fixtures above tub/shower units should be special-purpose, moisture-proof fixtures. 

Heating. Provide adequate heating in the bathroom. For comfort, this may require temperatures 3°F to 5°F warmer than the rest of the house. A quick-response auxiliary heat source may be helpful. 

Ventilation. Provide mechanical ventilation in every bathroom, with a minimum of eight (8) air changes per hour when operating (more for jetted tubs, spas, etc.). Choose a fan with a noise rating of 3 sones or less at high speed. 

Flooring. Specify all flooring with slip-resistant materials.

Paddle-type ceiling fans will not exhaust humid air, but they may be desirable in a high-ceilinged bathroom.

Fixtures. Basic bathroom clearances generally fall into two categories: fixture clearance (enough space for the fixture itself) and user clearance (enough space for the person using the fixture). Basic fixture and user clearances for individual fixtures are shown in Figure C. These serve as a good baseline for defining a bathroom layout (Figure D). When fixtures are ganged together in a bathroom, these basic clearances can sometimes be shared (Figure E), serving as the starting point for the small bathroom layouts shown in Figures G to J.   

Figure C: Fixture and User Clearances


When laying out a bathroom, allow space for the fixture as well as for the person using it. As a rule of thumb, all clearances are either 2, 3, or 5 ft. (this is sometimes called the 2-3-5 rule).
When laying out a bathroom, allow space for the fixture as well as for the person using it. As a rule of thumb, all clearances are either 2, 3, or 5 ft. (this is sometimes called the 2-3-5 rule).
Figure D: Basic Fixture Layout
When fixtures are ganged together, the 2-3-5 rule results in basic layout for a full bath (top) and half bath (above). The space allowances shown here — all multiples of 2, 3, or 5 ft. — provide a good starting point for working out the layout of a bathroom floorplan.
When fixtures are ganged together, the 2-3-5 rule results in basic layout for a full bath (top) and half bath (above). The space allowances shown here — all multiples of 2, 3, or 5 ft. — provide a good starting point for working out the layout of a bathroom floorplan.

Figure E: Shared Clearances


Elbow room from one clearance area may be shared with that of another area, reducing the overall clearance values. Clearances may vary, depending on the physical size of the occupants, available space, and client preferences.
Elbow room from one clearance area may be shared with that of another area, reducing the overall clearance values. Clearances may vary, depending on the physical size of the occupants, available space, and client preferences.


Small Bathroom Layouts

When fitting a bathroom into a tight space, departures can be made from the 2-3-5 rule. The layouts shown below illustrate a few functional bathroom layouts that can be adapted when floor space is limited.

Classic 5x7 bath. This is a classic small-space layout dictated by the length of a standard tub (5 ft.) and the minimum distance between tub, toilet, and lavatory (7 ft.). Two versions of this minimum bath are shown in Figure F.

Figure F: Classic 5 x 7 Bathrooms
The rectangular shape of the room shown at top makes this bath easy to fit into many floor plans. The door is shown on the end of the rectangle, but it can just as easily be put on the side (shown by dotted line). The second 5x7 bath (above) offers a little more room for a sink or 24-in. vanity, but at the expense of space in front of the toilet and with a minimal door (2’-4”). The only place to locate storage space in these baths is over the toilet, using open shelves or a mirrored upper cabinet.
The rectangular shape of the room shown at top makes this bath easy to fit into many floor plans. The door is shown on the end of the rectangle, but it can just as easily be put on the side (shown by dotted line). The second 5x7 bath (above) offers a little more room for a sink or 24-in. vanity, but at the expense of space in front of the toilet and with a minimal door (2’-4”). The only place to locate storage space in these baths is over the toilet, using open shelves or a mirrored upper cabinet.

Small baths with utilities. To reduce plumbing costs and save space, the core plumbing and heating utilities, as well as the washer and dryer, often are included near the bathroom. Two layouts are shown in Figure G.

Figure G: Small Baths with Utilities


This bath can be designed as either a long version or a short version. The short version includes the washer/dryer and water heater, with space for cabinets over the washer/dryer and shelving over the toilet (top). Lengthening the room stretches the vanity and allows for a floor-to-ceiling linen closet on the opposite wall. The other bath/utility core design (above) incorporates washer/dryer, water heater, and furnace, with a full bath that includes a linen closet.
This bath can be designed as either a long version or a short version. The short version includes the washer/dryer and water heater, with space for cabinets over the washer/dryer and shelving over the toilet (top). Lengthening the room stretches the vanity and allows for a floor-to-ceiling linen closet on the opposite wall. The other bath/utility core design (above) incorporates washer/dryer, water heater, and furnace, with a full bath that includes a linen closet.

Duplex townhouses or other narrow lot designs often require a narrow room layout. Figure H shows one solution for incorporating two baths and a utility room, keeping all the plumbing tightly arranged.

Figure H: Narrow Baths with Utilities


A duplex on a narrow lot may require a linear layout. This design keeps all the plumbing tightly arranged for an efficient rough-in.
A duplex on a narrow lot may require a linear layout. This design keeps all the plumbing tightly arranged for an efficient rough-in.

Tight baths. In tight spots, a shower with a curtain makes it possible to trim off square footage to get the bathroom down to just 30 sq. ft. (Figure I).

Figure I: Minimal Bath Variations


Although the design is an efficient square, the bath at top uses a 36-in. corner shower unit and requires a wall-hung sink. The bath at bottom is a series of compromises. A wall-hung sink is all that fits in this bath, and it requires an outswing door but includes room for shelving next to the toilet.
Although the design is an efficient square, the bath at top uses a 36-in. corner shower unit and requires a wall-hung sink. The bath at bottom is a series of compromises. A wall-hung sink is all that fits in this bath, and it requires an outswing door but includes room for shelving next to the toilet.

In a Cape or attic apartment, where headroom might be limited, a bath is possible if there’s space along one side for a mirror as well as room for a shower head 6 ft. off the floor (Figure J).

Figure J: Attic Bath


A bathroom with limited headroom is possible if the floor-to-ceiling height above the midpoint of the toilet, the top of a mirror, and the lowest wall in a shower are all at least 6 ft. high. 
A bathroom with limited headroom is possible if the floor-to-ceiling height above the midpoint of the toilet, the top of a mirror, and the lowest wall in a shower are all at least 6 ft. high. 


Designing to Accommodate Fixtures 

Lavatory. Provide a clear walkway of at least 21 in. (30 in. recommended) in front of a lavatory.

Lavatory clearance. Provide at least 12 in. (18 in. recommended) from the centerline of the lavatory to any side wall.

Double lavatory. Provide a minimum of 30 in. (36 in. recommended) between multiple lavatories, measured centerline to centerline. If space allows, a wider separation between lavs will be much more comfortable for users (Figure K).

Figure K: Lavatory Clearances
For baseline, minimum access, locate the centerline of a lav at least 15 in. from a side wall and space double lavs a minimum of 30 in. from center to center. For more comfortable use, allow at least 3 ft. of wall space per user and 42 in. for a single vanity width.
For baseline, minimum access, locate the centerline of a lav at least 15 in. from a side wall and space double lavs a minimum of 30 in. from center to center. For more comfortable use, allow at least 3 ft. of wall space per user and 42 in. for a single vanity width.

Toilets and bidets. Provide a clear walkway space of at least 21 in. (30 in. recommended) in front of a toilet or bidet.

Clearance. Provide at least 15 in. clearance (18 in. recommended) from the center of the toilet to any obstruction, fixture, or equipment on either side.

Where floor space allows, provide at least 6 in. of floor space between fixtures to allow for cleaning (Figure L).

Figure L: Cleaning Access


At least 6 in. of cleaning space between fixtures is recommended.
At least 6 in. of cleaning space between fixtures is recommended.

Toilet paper holder. Install the toilet paper holder within reach of a seated user. The ideal location is slightly in front of the toilet bowl, and centered 26 in. above the finished floor (Figure M).

Figure M: Toilet Paper Holder


Keep the toilet paper roll in front of the toilet. It is commonly placed in the corner or on the tank wall, but this forces a user to twist, which can actually cause injury.
Keep the toilet paper roll in front of the toilet. It is commonly placed in the corner or on the tank wall, but this forces a user to twist, which can actually cause injury.

Storage near bidet. Install soap and towel storage within reach of a person seated on the bidet.

Tub/shower. Provide a clear walkway of at least 21 in. (30 in. recommended) in front of a tub/shower (Figure N).

Figure N: Walkway in Font of Tub/Shower


In front of a tub/shower, provide a clear walkway of at least 21 in. (30 in. is recommended). 
In front of a tub/shower, provide a clear walkway of at least 21 in. (30 in. is recommended). 

Faucet. The bathtub faucet should be accessible to an adult standing outside the tub.

Grab bars. Install at least one grab bar in a bathtub or shower (Figure O). Some recommended locations include: 

  • Stall showers (one horizontal bar on the service wall to facilitate movement within the enclosure).
  • Tub/shower units (one horizontal bar centered on the service wall and a vertical bar near the outside edge where bathers enter and exit).
Figure O: Grab Bar Locations


Every tub and shower enclosure needs at least one grab bar to aid access into and out of the unit.
Every tub and shower enclosure needs at least one grab bar to aid access into and out of the unit.

Shower stalls. Make the interior of a shower stall at least 32x32 in. The preferred size for a typical adult is 36x42 in., which allows space for the user to step out of the stream of water. A fixed showerhead should be roughed in at 72 to 78 in. high.

Consider installing a bench or footrest within the shower enclosure. A 6x6x6-in. triangle in the corner can serve as a footrest. A built-in seat, 16 to 18 in. high by 12 to 20 in. deep, is ideal.

Jetted tubs. In homes with small children, raised tubs are generally safer than sunken tubs. However, no more than one step should lead to a tub platform (Figure P). The step must be at least 10 in. deep and no more than 71/4 in. high. With a raised tub, grab bars are essential to help people move into and out of the tub and to prevent slips.

Figure P: Tub Access


In homes with small children, a raised tub is safer than a sunken tub. But to limit the potential for slipping, there should be no more than one step up to the tub platform.
In homes with small children, a raised tub is safer than a sunken tub. But to limit the potential for slipping, there should be no more than one step up to the tub platform.

Jetted tubs must be installed in such a way as to have access to the pump motor for maintenance and repair.

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