Kitchen and Bath Design
This domain tests command of the NKBA planning guidelines plus the code items that concentrate in wet rooms: clearances, landing areas, ventilation, and waterproofing.
Core rules
- Work triangle: each leg 4-9 ft, sum 26 ft maximum, and no leg may pass through an island or tall obstacle.
- Aisles: 42 in work aisle for one cook, 48 in for two or more, 36 in walkways; increase where appliance doors open into the aisle.
- Landings: 36 in of counter on one side of the sink and 24 in on the other; dishwasher within 36 in of the sink edge; 15 in landing on the handle side of the refrigerator; 15 in beside a microwave; 36 in beside a wall oven.
- Heights: counters 36 in high and 24 in deep; uppers 18 in above the counter and 12-13 in deep.
- Bath: 30 x 48 in clear floor in front of shower and tub, 21 in in front of a toilet, 24 in in front of a lavatory, toilet centerline 15 in from a side wall; shower at least 30 x 30 in, 36 x 36 in preferred.
- Ventilation and waterproofing: bath fan 50 cfm intermittent or 20 cfm continuous; range hood sized to the appliance with makeup air considered; bonded waterproof membrane with 1/4 in per foot slope to the drain.
Worked example
A galley kitchen with sink to range 6 ft, range to refrigerator 8 ft, and refrigerator to sink 7 ft sums to 21 ft, with every leg inside 4-9 ft - compliant. When the client adds a wall oven in the island, the triangle is broken by an obstacle, so you redesign around work zones: prep at the sink, cooking at the range, and a separate baking zone with its own landing.
Traps
- Measuring the triangle straight through an island.
- Ignoring open appliance doors and drawer pulls when checking aisle width.
- Assuming a 36 in refrigerator fits a 36 in opening without air clearance.
- Skipping the waterproofing membrane because the tile itself is impervious.