Figure 6-17:  Bathroom Design Specs: (C) J Wiley S Bliss Guide to Bathroom Design: Best Practices

  • BATHROOM DESIGN - CONTENTS: Bathroom Design, Layout & Clearances Guidelines \. Bathroom design basic concepts. Bathroom layout dimensions & measurements for mirror height, shower clearances, bathtub clearances. Anti-scald recommendations for bathrooms.Flooring and ventilation suggestions for bathrooms. Lighting recommendations for bathrooms. Bathroom safety glass requirements. Typical bathroom layouts
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Bathroom design layout specifications: this article discusses current best design practices for residential bathrooms, including typical bathroom layouts, measurements & clearances for mirrors, showers, tubs.

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Bath Design Best Practices

We discuss anti-scald for bathrooms, bathroom flooring, ventilation, and lighting as well as bathroom safety glass needs.

This article series discusses current best design practices for kitchens and bathrooms, including layout, clearances, work space, and accessible kitchen and bathroom layout, clearances, turning space, grab bars, controls, etc. We include advice on choosing and installing kitchen countertops, cabinets, and kitchen or bathroom flooring, sinks, and other plumbing fixtures and fixture controls such as faucets. A list of kitchen and bath product manufactures and sources is included.

As described and detailed in Chapter 6 of Best Practices Guide to Residential Construction:

Bathroom Design Basics

A well-designed bathroom is comfortable to use, safe, durable, and easy to clean. Space planning revolves around the main fixtures and their required clearances. Proper clearances are critical to avoid problems such as banged elbows at a sink placed too close to a wall or difficult access to the tub faucet.

Bathroom safety concerns should be paramount in design decisions and material choices. For example, choose only nonskid flooring types and select tub and shower controls with foolproof antiscald protection (MIXING / ANTI-SCALD VALVES).

Avoid designs with sunken tubs or tub surrounds with steps, both of which are hazards.

Also remember that following code is not a guarantee of safety. For example, while it is legal to place bathroom lighting circuits downstream from the GFCI outlet, it is unwise since anything that trips the GFCI will also plunge the bathroom into darkness.


Bathroom Design Guidelines, Measurements, Clearances

The following recommendations are based on guidelines first published by the National Kitchen and Bath Association in 1992. While accessible design principles are provided separately below, NKBA now incorporates these principles into their recommendations for all projects.

Lavatories: Sink Clearances, Heights, Measurements

  • Clearances. Locate each sink so its centerline is at least 15 inches from a wall and 30 inches from the centerline of a second sink. The minimum walkway shown in front of the sink may not allow full accessibility (see Figure 6-16).
  • Height. While the standard vanity or sink height is 30 to 32 inches, 34 inches is a better compromise between shorter and taller users. If a bath has more than one vanity, set one at 30 to 34 inches and the other at 34 to 42 inches high.
Figure 6-16:  Bathroom Design Specs: Lav Clearances (C) J Wiley S Bliss

[Click any image or table to see an enlarged version with additional detail, commentary & source citation.]


Mirror Height Specifications for Bathrooms

The bottom edge of a mirror over a vanity should be no more than 40 inches above the floor, or 48 inches if the mirror is tilted forward.

Shower Dimensions, Clearances & Measurements for Bathrooms

Figure 6-17:  Bathroom Design Specs:  (C) J Wiley S Bliss

  • Clearances: Allow a minimum 21-inch walkway (30 inches preferred) from the front of the shower stall to a wall or fixture. These clearances may not allow full accessibility.
  • Size: Provide a minimum clear floor space inside the shower stall of 34x34 inches, preferably 36x36 inches or larger.

    For optimal accessible-bathroom comfort and safety, increase the size to 36x42 inches to 48 inches, which allows space for the user to step out of the stream of water to adjust the temperature (Figure 6-17).
  • Neoangle Showers: Neoangle showers are popular space savers, but the showering area is reduced in size due to the cut-off corner. The size of the corner cut varies from one model to another, with some cutting significantly into the shower space. For comfort, neoangles should be at least 42x42 inches.
  • Showerhead Location: Locate the showerhead supply pipe 72 to 78 inches above the finished shower floor. The installed showerhead will be 4 to 6 inches lower. If a handheld showerhead is used, it should be no higher than 48 inches at its lowest position.
  • Seating in Shower Stalls: Shower stalls should include a bench or seat that is 17 to 19 inches high and a minimum of 15 inches deep. The seat should not encroach on the minimum 34x34-inch floor space.
  • Doors for Showers: Shower doors must open into the bathroom, not into the shower stall.
  • Controls for Showers: Locate controls 38 to 48 inches off the floor and offset toward the room so they are accessible from both inside and outside the fixture.

Bathtub Clearances & Measurements

  • Clearances. Allow a minimum 21-inch walkway (30 inches preferred) from the open side of the tub to a wall or fixture. These clearances may not allow full accessibility.
  • Steps to a tub. Do not build steps leading to a bathtub or raised tub platform. These create a serious hazard. It is much safer for users to sit on the lip of the tub or platform and swing their legs in.
  • Sunken tubs are also a hazard. Safety rails should be installed to help users get in and out of any tub configuration.
Figure 6-18:  Bathroom Design Specs: Bath tub & shower clearances (C) J Wiley S Bliss

  • Controls. Offset controls toward the outside of the tub so they are accessible from both inside and outside the fixture.
  • Bathtub controls should be no more than 33 inches high.
  • If a handheld showerhead is used, it should be no higher than 48 inches at its lowest position (Figure 6-18).

Antiscald Protection Advice for Bathrooms

Protect all tubs and showers with a pressure-balancing valve or thermostatically controlled valve to limit water temperatures at a faucet or showerhead to 120°F or less. Recommend that homeowners set water heaters to no more than 120°F as an added precaution.

Details about anti-scald protection and devices are found at MIXING / ANTI-SCALD VALVES.

Toilets and Bidet Layout & Clearances for Bathrooms

Figure 6-19:  Bathroom Design Specs:  Toilet and Bidet Clearance Distances (C) J Wiley S Bliss
  • Clearances. Fifteen inches is the allowable minimum from the centerline of toilets and bidets to a fixture or wall, while 17 to 18 inches will create a more comfortable space (Figure 6-19).
  • Sixteen inches is the minimum for full accessibility as long as there is sufficient transfer space in front or on the side

  • Separate compartment. Compartmental toilet areas should be a minimum of 36x66 inches with a swing-out or pocket door.
  • Toilet paper holder. Locate with the center 26 inches above the floor, about 8 inches forward from the front of the toilet.

Flooring Choices & Suggestions for Bathrooms

Make all bathroom flooring slip-resistant.

Bathroom Ventilation Suggestions

Provide mechanical ventilation to the exterior (see BATHROOM VENTILATION for sizing details and other bath ventilation information).

Electrical Receptacles for Bathrooms - GFCI Needed

All bathroom receptacles must be GFCI protected. All light fixtures above a tub or shower must be rated for damp locations (tub) or wet locations (shower). Switches must not be reachable from within a tub or shower. Many bathrooms are wired so that all the lights go out if a GFCI is tripped.

Although this is allowed by code, it is neither safe nor convenient for the homeowners. See GFCI PROTECTION,Testing GFCIs AFCIs for details about these devices.

Lighting Suggestions for Baths

The vanity area should include both overhead and side lighting. Place side lighting centered at eye level (see Bathroom Lighting Guidelines). Where possible, provide natural lighting as well from a window or skylight area equal to at least 10% of the floor area.

Glass Safety Requirements in Bathrooms

All glass used in a tub or shower enclosure or other glass applications within 18 inches of the floor should be safety glazing, such as laminated glass, tempered glass, or an approved plastic.

Typical Bathroom Layouts

Bathrooms are divided into three main centers of activity: lavatory/grooming, toilet/bidet, and bathing/showering. In smaller bathrooms, these all share one common space, while in more spacious rooms, the grooming area or toilet area may be separated to allow greater flexibility and privacy for multiple users.

Larger spaces also allow for greater storage, such as a linen closet, within the bathroom space. Typical bathroom layouts with minimum dimensions for comfortable use are shown in Figure 6-20.

Figure 6-20:  Bathroom Design Specs:Typical bathroom layouts  (C) J Wiley S Bliss

Figure 6-20

[Click any image or table to see an enlarged version with additional detail, commentary & source citation.]

Design details for accessible bathrooms are discussed separately at BATHROOM DESIGN, ACCESSIBLE

Bathroom Lighting Specifications - references

See Bathroom Lighting Guidelines

Bath Fan Manufacturers

American Aldes Remote location single- and multi-port exhaust ventilators

Broan-Nutone LLC Low-sone Broan bath fans, also single- and multiport remote location exhaust ventilators; Nutone ceiling-mount bath fans

Fan Tech Remote location inline-duct fans

Kanalflakt Remote location inline-duct fans

Marley Engineered Products Ceiling-mount bath fans and general kitchen and room exhaust fans

Panasonic Low-sone, Energy-Star-compliant ceiling-mount, inline, and wall bath fans.

-- This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Adapted with permission from Best Practices Guide to Residential Construction.


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