What is included in the plumbing plans for an ADU?

Our ADU plumbing plans are a permit-ready drawing set that documents every part of your unit's water, waste, venting, and (where applicable) gas systems — everything a plan checker needs to approve the build and a plumber needs to install it correctly the first time.

What the drawing set contains

• Water supply (potable) layout and sizing. Hot and cold distribution from the point of connection to every fixture, with pipe sizing based on the fixture-unit demand so the system delivers adequate pressure and flow under simultaneous use.
• Drain-Waste-Vent (DWV) plan. The full gravity drainage and venting network — branch drains at minimum 1/4 inch per foot slope, traps, and a code-compliant vent system — typically supported by a DWV isometric or riser diagram that shows how every fixture drains and vents in three dimensions.
• Plumbing fixture schedule. Each fixture listed with its make/model and CALGreen low-flow rating (1.28 gpf toilets, 1.8 GPM showerheads, 1.2 GPM lavatory faucets, 1.8 GPM kitchen faucets) so flow compliance is verifiable at a glance.
• Water heater details. Type (heat-pump, tankless, or tank), location, connections, and the seismic strapping detail required statewide.
• Sewer or septic connection point. The tie-in method, slope, and connection detail to your existing lateral, a new lateral, or an approved septic system.
• Gas piping plan and sizing with shutoffs and sediment traps — included whenever the design uses gas appliances.
• Plumbing notes and details: CALGreen conservation notes, hot-water pipe insulation, backflow/cross-connection provisions where required, and general code references.

How it fits the rest of your set

The plumbing sheets coordinate with your mechanical and electrical plans — for example, water-heating efficiency lines up with your Title 24 report, and condensate or recirculation pumps appear on the right trade's sheet. Most homeowners building a detached unit choose the Full MEP package so all three disciplines arrive together and consistent.

Exact sheet requirements vary by jurisdiction and by your water/sewer district — confirm submittal expectations with your local building department.

Single plumbing plans start from $995 (scaled by ADU size), and two revisions plus city corrections are always included. Start your order or see how it works.