Bathroom fixture clearances and ventilation

Fixture clearancesNCRC R307.1 / Table P2705.1#

Residential plumbing fixtures have minimum clearance requirements around them so they can be used and maintained:

• Toilet: minimum 15 inches from the center of the bowl to any side wall, partition, or adjacent fixture
• Toilet: minimum 21 inches of clear space in front of the bowl
• Lavatory: minimum 15 inches from the center of the basin to any side wall
• Lavatory: minimum 21 inches of clear space in front
• Shower: minimum 30-inch by 30-inch interior dimension, and minimum 24 inches of clear space in front of the door

VentilationNCRC R303.3 / M1507.4#

Bathrooms must have either an openable window with at least 1.5 square feet of openable area, or a mechanical exhaust fan rated at least 50 cfm for intermittent operation or 20 cfm for continuous operation.

Exhaust fans must terminate outside the building envelope through a dedicated duct. Venting into an attic, soffit, or crawl space is not acceptable.

Shower waterproofingNCRC R307.2#

Shower walls must be finished with a non-absorbent surface to at least 72 inches above the drain inlet. Common acceptable surfaces include tile on cement backer board, solid surface panels, and fiberglass units.

Shower pans must be waterproofed with a listed shower pan liner that extends up the walls at least 3 inches above the top of the curb or finished threshold.

Required water supply#

Every residential bathroom must have hot and cold water at each lavatory, tub, and shower. Toilets and bidets require cold water only.

Common inspection flags#

Frequent bathroom failures:

• Toilet centerline less than 15 inches from an adjacent wall
• Shower smaller than 30 inches by 30 inches interior
• Exhaust fan duct terminating in the attic instead of through the roof or wall
• Shower pan liner not turned up the wall the required 3 inches
• Non-waterproof backer board used behind tile in a wet area