San Diego County's most experienced ADU plumbing contractor. 67 ADUs, custom homes, and remodels completed since 2024 — full rough-in to final inspection. Family-owned since 2008. CA Lic #926629.
San Diego's ADU boom is real — and so is the shortage of plumbing contractors who can keep up with it. Since 2024, Tri Express Plumbing has completed 67 ADU plumbing projects across San Diego County, plus custom homes and major remodels — totaling 80+ new construction and renovation scopes. We bring construction-phase experience, permit knowledge, and GC-ready reliability to every project — from Chula Vista to Rancho Santa Fe.
Detached units, garage conversions, and JADUs — more ADU plumbing volume than most San Diego plumbers complete in a decade.
Full custom home plumbing systems from the ground up, plus complex remodels — we understand every phase of construction from foundation to final.
Working directly with a homeowner? We pull all required plumbing permits and handle inspections. Working with a GC? We coordinate under your permit — no friction either way.
We work to your build schedule, coordinate with other trades, and communicate proactively. We don't need managing.
Underground rough-in, top-out, gas lines, water heater, fixture trim, and final walkthrough — one contractor, zero handoffs.
Same license, same crew, same accountability on every ADU plumbing San Diego project. CA Lic #926629.
Every ADU is different. The plumbing scope depends on unit type, site conditions, existing utility locations, and your local jurisdiction's requirements. Here's what our team handles on every project type.
Full system from ground up — underground sewer lateral, water supply, gas line, interior rough-in, vent stack, drain, water heater, and fixture trim. All permits and inspections handled in-house.
Bathroom rough-in, kitchen/kitchenette connections, tie-in to existing sewer and water lines. We assess existing stub-outs before any work begins. Full permit handling included.
We work from your architectural plans to design the most efficient rough-in layout and connect to existing drain, waste, and vent systems where code allows. Permits handled.
Junior ADUs require a private bathroom plus an efficiency kitchenette. Built within the existing home footprint — still requires full permits and inspection in every SD County jurisdiction.
Separate water meter ($3K–$10K) and gas meter separation ($1.5K–$5K). We coordinate with SDG&E, Otay Water District, and Sweetwater Authority for full utility splits.
Properties on private septic may need capacity assessment before the County approves ADU permits. We assess, provide written reports, and refer to trusted septic partners when needed.
ADU plumbing typically represents 10–15% of total ADU build cost. All prices include labor, materials, and permit fees. Final price confirmed in writing before any work begins.
| ADU Type | Scope | Starting Price |
|---|---|---|
| JADU (within existing home) | Bath rough-in + kitchenette | From $3,500 |
| Garage Conversion — 1 Bath | Rough-in + tie-in + fixtures | From $8,500 |
| Detached ADU — Studio / 1 Bath | Full rough-in + underground + fixtures | From $10,000 |
| Detached ADU — 1 Bed / 1 Bath | Full rough-in + underground + fixtures | From $12,000 |
| Detached ADU — 2 Bed / 2 Bath | Full rough-in + underground + fixtures | From $16,000 |
| Utility Separation — Water | Separate meter + new service | From $3,000 |
| Utility Separation — Gas | Separate meter coordination | From $1,500 |
| Septic Assessment | On-site visit + written report | From $295 |
* Prices include labor, materials, and permit fees. Final price confirmed after on-site assessment. SDG&E rebates may apply on qualifying high-efficiency water heater installations.
Every ADU site is different. Here are the six factors that most commonly drive final price — and what to ask your plumber before accepting a quote.
The farther your ADU sits from the existing sewer lateral and water main, the more trenching and pipe is required. We map utilities during the on-site estimate before pricing.
Each bathroom adds a toilet, sink, shower or tub, and associated drain, vent, and supply lines. Two-bath ADUs require significantly more rough-in labor than studios.
City of San Diego, City of Chula Vista, and unincorporated County all have different permit fee schedules and inspection requirements. We know each one and price accordingly.
Rocky or clay soil in eastern SD County increases excavation time and cost. Sloped lots require careful planning for drain slope compliance. Both assessed during your site visit.
Separate meters for water or gas — required for some rental setups and ADU financing programs — add $3,000–$15,000. We manage the full coordination process with utilities.
Corroded cast iron, undersized gas lines, or aging copper supply may need upgrading before ADU connections can meet current code. We inspect and report before any work begins.
Whether you're a homeowner on your first ADU build or a GC running a production schedule — here's exactly how we work.
Tell us your ADU type, location, and what your plans show for plumbing. We assess the scope and give you a realistic ballpark — no charge, no obligation.
We visit the property, locate existing sewer and water utilities, walk the ADU footprint, and provide a detailed written scope with fixed pricing.
Homeowner projects: We pull all required plumbing permits from the correct jurisdiction — City of San Diego, City of Chula Vista, or SD County — and handle all paperwork.
GC projects: You pull the project permit. We coordinate our plumbing scope under it and schedule all required plumbing inspections.
Sewer lateral connection, water supply trench, and gas line rough-in before slab pour or backfill. Coordinated with your GC so underground inspection clears on schedule.
After framing: interior drain, waste, and vent rough-in; supply lines; water heater location prep. We're on-site when your framing schedule calls for it — not when it's convenient for us.
We schedule and attend the plumbing rough-in inspection. Any corrections addressed immediately — your project doesn't wait on us.
After drywall: water heater, fixture trim, supply connections, final testing. Every fixture, every valve, every connection verified before we leave the site.
We walk the completed ADU, confirm full permit sign-off, and hand over all documentation. Done right, fully documented, and ready for occupancy.
If you build ADUs in San Diego County, you already know the problem. Most plumbing subs are built for service work. Tri Express is built for construction. We completed ADU plumbing on 80+ units in 2024 — we know the phases, the sequencing, and what happens when underground inspection slips a day.
We pull permits and complete ADU plumbing throughout all San Diego County jurisdictions. No extra charges for any area within our service zone. Each jurisdiction has its own permit office, fee schedule, and inspection process — we know them all.
Real answers from our family team — based on 80+ ADU plumbing projects across San Diego County.
