How much space do bathroom fixtures need?
Most US homes follow the International Residential Code (IRC). Here are its common minimum clearances for toilets, sinks, showers and baths, the drain slope rule, and a free layout checker.
How much space does a toilet need?
Under IRC sections R307.1 and P2705.1, the centre of a toilet must be at least 15 inches (381 mm) from any side wall or obstruction, and at least 15 inches from the centre of a fixture next to it. There must also be at least 21 inches (533 mm) of clear floor space in front of the toilet.
- Toilet: 15″ from centre to a side wall or fixture; 21″ clear in front.
- Sink (lavatory): 21″ clear in front.
- Bathtub: 21″ clear in front.
- Shower: at least 900 in² inside and 30″ across in each direction; 24″ clear in front of the opening.
How big does a shower need to be?
The IRC asks for a shower with at least 900 square inches of floor area that can fit a 30-inch circle, which in practice means at least 30 × 30 inches. Many designers prefer 36 × 36 inches or larger for comfort. Leave at least 24 inches of clear space in front of the shower opening.
How much slope does a drain pipe need?
IRC section P3005.3 sets a minimum fall of ¼ inch per foot for drain pipes 2½ inches in diameter or smaller, and ⅛ inch per foot for pipes from 3 to 6 inches. So a 10-foot run of 2-inch pipe needs to drop at least 2½ inches from one end to the other.
drop = run length (ft) × ⅛″ for 3″ to 6″ pipes
What is a toilet rough-in?
The rough-in is the distance from the finished wall behind the toilet to the centre of the floor drain. Twelve inches is the most common size for new toilets, while 10 and 14 inch models exist for older homes. Measure yours before buying a new toilet, because the wrong size will not fit.
Check your layout
Roomveil lets you enter your bathroom size, drag a toilet, sink, shower and bath into place, and shows green or red zones for the space each one needs. Local codes can differ from the IRC, so always check with your local building department.
These are common rules of thumb and code minimums, given for planning. Always check the product label, the maker's instructions and your local building code before you buy or build.