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AI drafting for plumbing risers

AI Plumbing Riser Diagram Drafting

A riser diagram restates the floor plans in another form, so every fixture, stack, and pipe size on the plans has to appear again, correctly, on the riser. Nomic drafts the waste, vent, and water risers and isometrics in CAD from your plumbing plans, tallies fixture units floor by floor, sizes pipe from the code tables your engineer selects, and flags every place the risers and the plans disagree.

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Last reviewed: November 2026

You send

  • Plumbing floor plans as DWG or PDF
  • The engineer's sizing tables and the code edition
  • The fixture schedule or cutsheets
  • Water service static pressure from a flow test or the utility
  • Past riser diagrams that show your house style

Nomic hands back

  • Sanitary and vent riser diagrams as DWG files
  • Domestic water riser diagrams with valves and pressure reducing valves
  • Fixture unit tallies in Excel
  • A list of riser and plan mismatches for the engineer of record
ROOFEL. 156'-0"LEVEL 4EL. 142'-0"WCLAV3/4" TO FIXTURESLEVEL 3EL. 128'-0"WCLAV3/4" TO FIXTURESLEVEL 2EL. 114'-0"WCLAV3/4" TO FIXTURESLEVEL 1EL. 100'-0"WCLAV3/4" TO FIXTURES4" SAN3" V2" CWVTR6" BUILDING DRAIN TO SITE SEWERBFP1APLUMBING RISER DIAGRAMSCALE: NONE1234CONSULTING ENGINEERSREVISIONS1ISSUED FOR REVIEWPROJECTWESTFIELD LABSSCALENONEDATE08/17/2026KEY PLANSHEET TITLEPLUMBING RISERDIAGRAMSHEET NUMBERP-501

On the sheet

Plumbing Riser Diagram, annotated

A riser diagram showing waste, vent, and water stacks through every level of the building.

  1. 1Waste stack through every floor
  2. 2Vent through roof
  3. 3Branch to the fixtures on each level
  4. 4Domestic water riser and backflow preventer

The problem

Risers fall out of step with the plans

On a six story apartment building, one sanitary stack might pick up a kitchen and a bathroom group on every floor, and the riser has to show each branch, the fixture units it carries, the stack size, the vent stack connection, and the cleanout at the base. Drafting that once takes careful counting, and redrafting it after the architect flips two unit types on Level 3 is where the errors come in.

Reviewers find the same problems on riser after riser: a stack that is 3 inches on the riser and 4 inches on the plan, a fixture unit total that still counts a deleted unit, a vent stack with no size, or a water riser that never shows the pressure reducing valve the static pressure calls for. Each one is a consistency error between two sheets that someone has to check line by line.

01 / Diagram

Risers drawn from the floor plans

Nomic reads the plumbing floor plans, finds every stack and riser, and draws the sanitary, vent, and domestic water risers with each floor branch in place. Fixture units come from the code table and fixture types you set, and pipe sizes come from the sizing tables your engineer selects.

  • Sanitary and vent risers with stack, branch, and vent sizes
  • Cold, hot, and hot water return risers with valves and pressure reducing valves
  • Isometrics for toilet room groups drawn in your house style
02 / Tally

Fixture units that trace back to a plan

Every fixture unit on the riser traces back to a fixture on a floor plan. Nomic writes the tally branch by branch, totals each stack, and marks any floor where the count on the riser and the count on the plan disagree.

  • Drainage fixture units per branch, per floor, and per stack
  • Water supply fixture units for the water riser and the service size
  • The full tally in Excel for the engineer's sizing review
03 / Check

Plans and risers checked against each other

Nomic compares the risers with the plans sheet by sheet and checks sizes against the code tables for the edition you name. Each mismatch is listed with both sheet numbers, and the final call on any size stays with your engineer.

  • Stack and branch sizes matched between plan and riser
  • A cleanout at the base of every stack
  • Static pressure checked against the threshold for a pressure reducing valve

Checked against

The code and documents behind every sheet

Name the editions the project is designed to and Nomic checks its own drawing against them before handing it back. Your engineer or architect of record makes the final call and stamps the set.

  • IPC Table 709.1 drainage fixture units
  • IPC Section 710 drainage pipe sizing
  • IPC Chapter 9 vents
  • IPC Appendix E water pipe sizing
  • Uniform Plumbing Code Chapters 6, 7, and 9
  • The project plumbing floor plans

How it works

From a sentence to a stamped set

  1. Step 1

    Ask for the drawing

    Say what the sheet needs to show and attach the backgrounds, markups, cutsheets, or photos. A sentence is enough to start.

  2. Step 2

    Nomic drafts it in CAD

    Nomic works in CAD on its own computer, on your layers and blocks, following how your firm drew the same thing before. It saves real DWG files to the project.

  3. Step 3

    Nomic checks its own work

    The drawing is checked against the code editions you name and the source documents. Everything Nomic drew is clouded, and open questions are listed.

  4. Step 4

    Your team reviews and stamps

    Your engineers and architects review the clouded changes, make the final call, and issue the set under their own stamp.

FAQ

Frequently asked questions

Yes. Nomic works in CAD on its own computer and saves riser diagrams as DWG files, drawn from your plumbing floor plans. Each stack and riser shows its branches, fixture units, pipe sizes, vents, cleanouts, and valves, and Nomic checks the riser against the plans before your engineer reviews it.

Nomic tallies drainage and water supply fixture units from the code table and edition you name, branch by branch and stack by stack, and exports the tally to Excel. Your engineer confirms the fixture types, picks the sizing table, and makes the final call on every size.

A riser diagram is a schematic elevation of the vertical stacks with each floor branch shown where it connects. An isometric shows the piping in three dimensions at 30 degrees, which is common for toilet room groups and water distribution. Nomic draws both in your firm's style.

No. Your engineer sets the sizing method and the tables, and Nomic sizes stacks, branches, and vents from them. Anything the criteria do not cover, such as a vent stack with an unusual developed length, goes on the open questions list.

No. Nomic works in CAD on its own computer and saves DWG files to your project, which open in AutoCAD or any DWG editor. If your plumbing is modeled in Revit, Nomic hands back DWGs and a change list your modeler links into the model.

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