What is a curbless shower?

A curbless shower has a very low or absent entry threshold, allowing someone to walk or roll inside. Unlike a bathtub, it does not offer soaking. Its waterproof membrane should reach the surrounding walls and adjacent floor, so include those boundaries when requesting a written installation scope.

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By InstaBids editorial team with AI research agents. Updated 2 November 2026

What this means for your home project

Look at the shower entrance: note whether its threshold is very low or absent, the entry feature described in NC State’s guide. Source: NC State University Center for Universal Design, read 2026-11-02.
Request a written floor-height plan identifying whether the shower floor will be lowered below the adjacent floor. Use the reply to identify the proposed recessed-floor approach. Source: NC State University Center for Universal Design, read 2026-11-02.
Request a waterproofing drawing showing the membrane at the pan bottom, surrounding walls and adjacent floor. Use those marked boundaries to compare the proposed installation scope. Source: NC State University Center for Universal Design, read 2026-11-02.

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Can any bathroom have a curbless shower?

A flush entry is a construction decision, so do not assume every existing bathroom can accept it unchanged. NC State’s 2003 residential guide describes two approaches: lower the shower floor or raise the surrounding finished floor. Raising it can create a level change at the bathroom door; a custom recessed shower requires structural redesign. “The first, and preferred, is to drop the floor under the shower below the adjacent floor level.” Source: NC State University Center for Universal Design, read 2026-11-02. “The second is to set the shower directly on the subfloor and build up the finished floor of the room.” Source: NC State University Center for Universal Design, read 2026-11-02. “This second method usually creates an undesirable level change at the door into the bathroom or in hallways that must be later beveled or ramped.” Source: NC State University Center for Universal Design, read 2026-11-02. “The floor structure must be reengineered to accommodate a “dropped” floor.” Source: NC State University Center for Universal Design, read 2026-11-02.

How far past the shower will the waterproofing go?

Ask for the membrane boundary to be drawn into the written scope, including the surrounding walls and adjacent bathroom floor. The waterproof membrane is the water barrier forming the bottom of the shower pan. NC State’s 2003 guide recommends extending it into those areas in both wood-frame and concrete-slab construction; that passage specifies no extension distance. “In both wood frame and concrete slab construction, a waterproof membrane should be used to form the bottom of the shower “pan” and should extend up into the surrounding walls and out into the floor area adjacent to the shower.” Source: NC State University Center for Universal Design, read 2026-11-02.

Linear drain or centre drain?

Choose the drain with its floor layout and position in mind. A linear drain can accept flat sloping planes toward its sides and ends; the waste pipe must suit that drain. TileLetter’s 2018 technical answer, discussing an outdoor shower near a wall, cautions that some round drains cannot sit close enough to a wall for waterproofing and drainage. Use that positioning distinction when discussing a centre-drain alternative; it is not a curbless-only rule. “With a linear drain, the floor of the shower can be uniformly sloped in one or more flat / properly sloped planes toward the sides and ends of the drain.” Source: National Tile Contractors Association / TileLetter, read 2026-11-02. “Having said this, the waste pipe needs to be carefully located and sized to accommodate the linear drain being used.” Source: National Tile Contractors Association / TileLetter, read 2026-11-02. “A typical round clamping ring drain and many round bonding flange drains may not be able to be positioned close enough to the wall to allow for proper waterproofing connections and/or slope to the drain.” Source: National Tile Contractors Association / TileLetter, read 2026-11-02. “While a threshold height up to ½″ (if properly beveled) is permitted, trench drains and other designs that allow a flush transition to the shower floor will provide easier access.” Source: U.S. Access Board, read 2026-11-02.

Do curbless showers work for aging in place?

The low entry can help someone walk or roll into the shower, but size also belongs in an accessibility plan. As a design reference, the 2010 Americans with Disabilities Act (ADA) Standards specify a standard roll-in compartment at least 30 inches wide by 60 inches deep, with a 60-inch entry. These are requirements for facilities covered by those Standards, rather than a universal private-home specification. “These showers feature a very low or no threshold at all so users may easily walk or roll into the unit.” Source: NC State University Center for Universal Design, read 2026-11-02. “Standard roll-in type shower compartments shall be 30 inches (760 mm) wide minimum by 60 inches (1525 mm) deep minimum clear inside dimensions measured at center points of opposing sides and shall have a 60 inches (1525 mm) wide minimum entry on the face of the shower compartment.” Source: U.S. Access Board, read 2026-11-02.

Can accessible shower compartments have doors instead of curtains?

A door may be possible, but its movement and opening must preserve access. The Access Board says a door on an alternate roll-in shower may work with at least 36 inches of clear opening when open 90 degrees. Its ADA guide also cautions that doors on standard roll-in and transfer compartments typically obstruct required access. Apply this guidance within its accessibility scope. “Shower enclosures, including doors, cannot obstruct controls, faucets, shower spray units, or transfer from wheelchairs to transfer seats (§608.8).” Source: U.S. Access Board, read 2026-11-02. “Shower doors on transfer compartments and standard roll-in compartments will typically fail this test.” Source: U.S. Access Board, read 2026-11-02. “A door may be possible on an alternate roll-in shower if the shower opening provides a clear width of at least 36″ minimum when the door is open 90 degrees.” Source: U.S. Access Board, read 2026-11-02.

Sources

Curbless Showers: An Installation Guide — NC State University Center for Universal Design; published 2003; read 2026-11-02.
Guide to the ADA Accessibility Standards: Bathing Rooms — U.S. Access Board; read 2026-11-02.
2010 ADA Standards: Shower Compartments — U.S. Access Board; published 2010; read 2026-11-02.
Round drain or linear drain — National Tile Contractors Association / TileLetter; published 2018-12-15; read 2026-11-02.