Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
American Standard Home Additions & ADU: The San Diego Owner’s Guide
American Standard home additions and ADU construction in San Diego typically runs $53,100 to $153,400 for a permitted addition, and $106,200 to $259,600 for a fully permitted accessory dwelling unit. Most homeowners discover they need this work when their family outgrows the floorplan, an aging parent needs to move closer, or rental income becomes necessary to offset a San Diego mortgage. The part that “fails” here isn’t a single component: it’s the house itself, no longer matching what your life requires.
At Mason Remodeling Co San Diego, we handle the full scope of American Standard-compatible home additions and ADUs, from foundation to finish. That means one written price before any work starts, a named crew with photo ID at your door, and a 365-day Done Right Promise on the finished build. Tell me what’s broken. I’ll tell you what it takes.
Which American Standard Models This Applies To
American Standard doesn’t make “home addition” components the way they make faucets or water heaters, but their plumbing fixtures, HVAC equipment, and water heating systems are the most common names we encounter inside San Diego additions and ADUs. When we build an addition or ADU, we spec American Standard-compatible rough-ins and finishes throughout: their Cadet and Champion toilet lines, their colony and Portsmouth tubs, and their gas and electric water heaters all require specific framing dimensions and valve types that differ from Kohler or Moen equivalents.
The compatibility gotcha most homeowners don’t know: American Standard toilets use a 12-inch rough-in on most models, but their compact elongated models need a 10-inch rough-in. If your addition’s framing is set at standard 12 inches before the fixture is chosen, you’ll be moving walls or swapping models late in the job. We check this during the framing walkthrough, not after drywall. For ADUs specifically, San Diego code requires a separate water shutoff for the secondary unit. That’s not a preference: it’s a permit condition, and it changes how we plumb the American Standard fixtures from day one.
OEM versus aftermarket: for American Standard fixtures, we always install OEM valves and internal components. The aftermarket equivalents for their ceramic disc cartridges and flush valves are inconsistent, and a $45 aftermarket cartridge that fails in a new ADU isn’t a savings. It’s a callback you shouldn’t have to deal with.
Styles & brands we work with
Signs Your American Standard Home Additions & ADU Is Failing
- You’re paying San Diego rent for space you don’t have. A two-bedroom rental in Clairemont or North Park now costs more per month than the payment on a properly financed ADU construction loan. When the numbers cross, the house has failed its purpose.
- Your plumbing stack can’t handle another bathroom. Older San Diego homes, especially in Mission Hills and Kensington, were built with 3-inch cast iron or even galvanized waste lines. Adding a second full bath without upsizing the stack leads to slow drains and sewer gas. This is a real constraint we diagnose before pricing the addition.
- Your electrical panel is maxed out. A 100-amp panel can’t support an ADU with electric range, mini-split HVAC, washer/dryer, and water heater. We see this weekly in Clairemont and Normal Heights homes from the 1950s and 1960s. The panel upgrade becomes part of the honest price.
- Slab or foundation movement shows in new cracks. San Diego’s expansive clay soils in areas like Rancho Peñasquitos and Scripps Ranch shift with seasonal moisture. If you’re planning an addition, we evaluate the existing slab first. Building on a moving foundation guarantees the new work moves too.
- Your setback and lot coverage limits the ADU. San Diego’s 2020 ADU ordinance relaxed some rules, but you can’t build a 1,200-square-foot unit on every lot. We calculate your actual buildable envelope before you spend money on plans that won’t pass plan check.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
In San Diego, a permitted home addition runs $53,100 to $153,400. ADU construction runs $106,200 to $259,600. These aren’t national averages. They’re what we see in this city after 20-plus years of San Diego County work, and they assume plan check fees, San Diego permit costs, and the seismic and energy code requirements specific to this region.
What drives the range within those numbers:
| Cost Driver | Low End | High End |
|---|---|---|
| Site prep and foundation (flat lot vs. sloped San Diego lot) | $3,500 | $18,000 |
| Plumbing rough-in (American Standard fixtures, separate ADU shutoff) | $4,000 | $12,000 |
| Electrical (subpanel or main panel upgrade) | $2,500 | $9,500 |
| HVAC (mini-split vs. ducted) | $4,000 | $14,000 |
| Interior finishes (flooring, drywall, paint, trim) | $18,000 | $60,000 |
| Permits, plan check, and school/impact fees | $6,000 | $25,000 |
Every Mason Remodeling Co San Diego addition and ADU gets a written price before any work starts. That price includes all labor, materials, permits, and the American Standard fixtures specified. If the number changes, it changes in writing, approved by you, before the change is made. No verbal handshakes, no surprise invoices at final walkthrough.
We also include a written guarantee on the entire build for 365 days from the completion date. If something we installed fails, we return and fix it free. That includes the American Standard plumbing fixtures, the drywall seams, the trim work, everything.
DIY or Call Us?
An addition or ADU is not a DIY project. There’s no honest split on this one. We’re talking about structural framing, electrical panels, gas line runs, and foundation work, all of which require San Diego County permits and inspections. A homeowner who frames a wall incorrectly creates a life-safety risk for everyone in the house. A homeowner who connects a gas water heater incorrectly creates a carbon monoxide hazard. These aren’t skills you pick up watching a weekend of videos.
What you can do before calling us: measure your lot and note your setbacks, check your current electrical panel amperage, find your water heater’s age and location, and write down what you actually need the space to do. Then call (619) 673-9302 and ask for a free estimate. We’ll walk the property, tell you what’s buildable, and put the number in writing.
We’re an independent San Diego general contractor. We are not affiliated with American Standard, but we install and service their fixtures in additions and ADUs across San Diego every week, alongside KraftMaid cabinetry and Cambria and Silestone surfaces when the job calls for them.
FAQs
A permitted home addition in San Diego typically takes 4 to 8 months from permit approval to final inspection; a detached ADU runs 6 to 12 months depending on site conditions, utility trenching, and plan check timelines. San Diego’s Development Services Department currently has longer plan check review times than pre-2020, so we factor that into every timeline we quote. Call (619) 673-9302 and we’ll give you a realistic schedule for your specific lot after a free site visit.
Yes, garage conversions are often the fastest ADU path in San Diego, running $35,400 to $94,400 depending on whether the slab, electrical, and roof structure are sound. Some San Diego garages from the 1940s and 1950s have unreinforced masonry walls or slab deterioration that makes conversion more expensive than new construction, and we’ll tell you which one you have before you commit. Call us for a free assessment.
Yes, Mason Remodeling Co San Diego pulls every permit for additions and ADUs we build in San Diego, and we schedule and pass every inspection with the city or county. The permit fees are included in your written price, and you get final inspection sign-off before we consider the job complete. If a permit is pulled under our name, we’re responsible for the result.
No. Your written price is your price. The only price changes on a Mason Remodeling Co San Diego project come from change orders you approve in writing, in advance, for scope you add. If we discover an unforeseen site condition, we show it to you, explain the cost, and get your written approval before touching it. That’s the way we’ve worked since 2004, and that’s the way it stays.
Written by Isaac Pruett, Owner, Mason Remodeling Co San Diego at Mason Remodeling Co San Diego, serving San Diego and nearby areas.
