Bathroom design requires that a lot of fixtures be packaged into a place that’s typically on the smallish side. The International Residential Code, on which many local construction codes are based, specifies dimensions that restrict where you can place bathroom fittings, along with the National Kitchen and Bath Association presents guidelines for great bathroom design that need much more room.
The IRC needs bathroom door openings be 24 inches wide. The NKBA is much more conservative, recommending the obvious opening of a doorway be at least 32 inches wide, which demands a doorway width of 34 inches. To comply with the Americans with Disabilities Act, a toilet doorway must have a clear opening of 32 inches. The NKBA additionally recommends that no door, when available, should interfere with the functioning of any other doorway or the secure and comfortable use of any toilet fixture.
The IRC requires clear floor space of at least 21 inches in front of toilet sinks; the NKBA recommends at least 30 inches. The IRC says a sink must be placed so its centerline is at least 15 inches from any wall and its border is no closer than 4 inches from any wall or other sink; the centerlines of dual sinks must be at least 30 inches apart. The NKBA recommends 20 inches between a sink’s centerline and the wall and 36 inches between the centerlines of dual sinks.
Tubs and Showers
The IRC specifies 24 inches of clear space in front of showers and 21 inches in front of bathtubs; the NKBA recommends increasing both dimensions to 30 inches. The minimum interior size to get a shower, according to the IRC, is 30 inches square, but the NKBA recommends at least 36 inches square. The code says that a 30-inch disc must fit inside the shower, thus a square shower with an angled doorway at one corner needs to measure about 32 inches on a side to meet that requirement.
The IRC says there should be 15 inches between the centerline of a toilet and any wall, fixture or barrier; the NKBA recommends bumping that measurement around 18 inches. Clear floor space in front of the toilet should be at least 21 inches based on the IRC, 30 inches based on the NKBA. After the toilet is enclosed in another space, that space must be at least 30 inches by 60 inches to satisfy the IRC specifications. The NKBA says that the enclosure should be at least 36 inches by 66 inches, not including any distance required by an inward-swinging door.
A toilet’s overhead measurement might also restrict where it is possible to put fixtures inside the area. The IRC requires a minimum ceiling height of 80 inches over all fittings and over the required clear floor space in front of fittings. Showers must also have a minimum 80-inch ceiling height above their entire 30-by-30-inch interior space.