Sinks

For Forum's purposes...

Kitchen/laundry/bar sinks:

• stainless steel 99% of the time

• standard kitchen sinks typically require min 36" base cabinet for installation

  • can be single bowl, double bowl (equal) or double bowl (offset)

  • can be drop-in, undermount or farmhouse style (apron front)

  • can be standard or accessible (shallower with drain hole offset to rear)

• laundry/bar/prep sinks are basically smaller single bowl kitchen sinks

  • can be drop-in or undermount

• there are also "trough sinks" that are long and narrow, usually without faucets, used as ice wells for bottled beverages (not for use in units)

Bathroom sinks are called lavatories (a subset of sinks):

• typically require min 27" or 30" vanity cabinet

  • can be stainless steel, porcelain, or synthetic material

  • can be drop-in (called "self-rimming"), undermount, or vessel style (raised)

  • can be almost any shape:

    • rectangular (most common)

    • oval

    • round

    • square

Reference Plane Offset for Sink Placement – 3 1/2" from Front of Countertop

• The 3 1/2" offset reference plane from the front edge of the countertop was established to ensure adequate clearance for sink mounting hardware. This spacing allows for proper installation of undermount or drop-in sinks by providing sufficient room within the countertop depth to accommodate mounting brackets, clips, and structural reinforcement without interference from the front edge or cabinetry face.

Justification for Rear Drain Placement:

4 Inches from the Back of Sink

• In accordance with ADA (Americans with Disabilities Act) Standards for Accessible Design, Forum has chosen to place the rear drain location 4 inches away from the interior back of the sink bowl. This decision aligns with both the spirit of ADA compliance and industry best practices, as detailed below.

ADA Standards and Compliance

• The ADA does not provide a specific measurement for the distance between the back of the sink and the drain location. Instead, it emphasizes clear knee and toe space under sinks (minimum 30" wide and 17"–25" deep) and the requirement that plumbing systems must not impede accessibility for wheelchair users. To protect this clearance, ADA guidance and the U.S. Access Board recommend rear-positioned drains and protected or insulated piping.

Manufacturer Standards and Industry Norms

• Upon researching several leading manufacturers of ADA-compliant sink systems, a pattern emerged regarding drain placement:

  • Elkay, DuPont Corian, and Truebro all recommend or manufacture products with rear drain configurations that maximize under-sink clearance.

  • Across technical specifications and product drawings from these manufacturers, rear drain placements between 3"–5" from the back of the interior portion of the sink bowl are most common. A 4-inch offset sits comfortably within this range and provides a balanced compromise between functionality and compliance.

Justification for ADA and Non-ADA Sink Bowl Depths: 5" and 8" Respectively

• Forum has standardized its sink bowl depths at 5 inches for ADA-compliant sinks and 8 inches for non-ADA sinks. This design decision was made after careful review of the ADA Accessibility Standards, coordination with manufacturing best practices, and consideration for user functionality and comfort.

ADA Sink Bowl Depth – 5 Inches

• The Americans with Disabilities Act (ADA) sets forth critical clearance requirements under sinks to ensure accessibility for individuals using wheelchairs. While the ADA does not specify an exact sink bowl depth, it does mandate:

  • A maximum sink height of 34" above the finished floor.

  • A minimum knee clearance of 27" from the floor to the underside of the sink.

  • Protection of under-sink plumbing to avoid contact.

  • Given these constraints, only 7 inches remain between the underside of the sink surface and the floor for the bowl and countertop combined. With standard countertop thicknesses typically ranging between 1"–1.5", Forum has chosen a 5-inch bowl depth to ensure compliance, comfort, and flexibility across a variety of installations.

• This decision:

  • Maximizes usable knee space for wheelchair users.

  • Avoids encroachment into required clearances, especially once plumbing components are installed.

  • Aligns with industry standards—manufacturers such as Ruvati and American Standard commonly offer 5"–6" ADA sinks.

Non-ADA Sink Bowl Depth – 8 Inches

• For non-ADA applications, where knee clearance and height restrictions are not a concern, Forum has chosen a deeper 8-inch bowl depth. This depth is a commonly accepted standard in residential and commercial sink design and provides:

  • Greater volume for washing large cookware or handling high-volume tasks.

  • Improved splash control due to the added vertical containment.

  • A comfortable working depth without excessive bending for most users.

• By distinguishing between the two depths—5 inches for ADA and 8 inches for non-ADA—Forum ensures both code compliance and functional performance, while also simplifying product standardization across projects.

Naming Strategy:

F.PlumbingFixtures.Sink.[Usage].[Form].[Mount].[Style].[Shape]

• Usage: Lavatory, Kitchen, or omit if universal

• Form: Single, Double, Double.Offset

• Mount: Dropin, Undermount, Vessel

• Style: Farmhouse, or leave blank if standard

• Shape (optional): Oval, Rectangle — used mostly for lavatories