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.
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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
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
Figure D: Basic Fixture Layout
Figure E: Shared Clearances
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
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
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
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
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
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
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
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
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
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
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
Jetted tubs must be installed in such a way as to have access to the pump motor for maintenance and repair.