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Toto Home Additions & ADU: The Thousand Oaks Owner’s Guide
If you’re planning a Toto-equipped addition or ADU in Thousand Oaks, expect to invest between $45,000 and $130,000 for a home addition, and $90,000 to $220,000 for a full ADU build, depending on square footage, site conditions, and finish level. We’re Mason Remodeling Co Thousand Oaks, and we spec Toto fixtures into these projects every month, from Toto toilets and bidet seats to basins and tubs. We’re an independent contractor, not a Toto dealer or subsidiary, which means we install what actually works for your space and budget, not what a corporate program tells us to push.
Most Thousand Oaks homeowners call us when the layout stops working: aging parents need a ground-floor suite, a growing family needs a second bathroom, or an existing garage is dead space and an ADU would cover the mortgage. The Toto part matters because these projects put plumbing under real demand. A toilet that runs constantly or a poorly seated wax ring in a new addition means drywall work and a callback nobody wants. We plan the rough-in so the finish fixtures, including Toto, land exactly where the drawings say they will.
Which Toto Models This Applies To

Toto makes a broad line, and not every model fits every rough-in. This catches more than a few homeowners off guard. The Drake and Drake II toilets use a standard 12-inch rough-in, which fits most Thousand Oaks homes built after 1990. The Toto Ultramax II and Aquia IV, however, use a 10-inch or 14-inch rough-in depending on the model, and if your plumber set the flange at 12 inches based on the old toilet, the new Toto won’t sit right without moving the drain. That’s a $900 to $1,800 correction in a remodel, and it’s the kind of thing we check before drywall ever goes up.
For ADU builds, the Toto wall-hung models, like the Aquia and Nexus lines, need an in-wall carrier system installed during framing, not after tile. If you’re dreaming of a floating Toto in a new ADU bathroom, tell us before concrete or framing, because retrofitting the carrier later means opening the wall. For bidet seats, Toto’s Washlet line requires a dedicated GFCI outlet within three feet of the toilet. Older Thousand Oaks bathrooms rarely have one, which is one more reason the pre-construction walkthrough matters. When it comes to OEM versus aftermarket, Toto’s genuine parts, particularly fill valves and flappers, outlast generic equivalents by years. We stock genuine Toto parts on the truck whenever possible, and we’ll tell you plainly when an aftermarket part will do the same job for less.
Styles & brands we work with







Signs Your Toto Home Additions & ADU Is Failing
- Water running intermittently with no one using the fixture. This usually points to a failing fill valve or a flapper that’s lost its seal. In hard-water areas of Thousand Oaks, mineral buildup accelerates this. The fix is often under $200 in parts and labor if caught early.
- Wobbly toilet that rocks when you sit. The flange is likely cracked or the subfloor has softened. In a new addition, this can signal the ring was set on an uneven surface. Ignoring it leads to a slow leak under the tile.
- Constant hissing from the tank after flushing. The fill valve isn’t shutting off completely. It’s wasting water daily and will eventually fail at the worst possible time. A replacement takes about 30 minutes.
- Caulk line around the base turning dark or separating. Moisture is escaping the wax ring or the bowl-to-floor seal. That slow leak, left for months, rots subfloor and invites mold. We’ve cut into more than one Thousand Oaks bathroom floor and found the joist was still salvageable only because the owner called early.
- Bidet seat not heating or cycling off. Toto Washlet seats have a service life in California that tracks with power quality. Surges and outages in the Conejo Valley can shorten the control board’s life. Before replacing the seat, we test the outlet and the dedicated circuit.
See the difference
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After
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AfterReplacement Cost & What’s Included

For a Toto fixture swap inside a masonry or addition project, the installed price ranges from $800 to $3,000 depending on the fixture. That includes the unit, wax ring or gasket, supply line, angle stop if needed, and disposal of the old fixture. If we’re setting a Toto into a new addition or ADU rough-in, the fixture cost is rolled into the larger project scope, but we’ll always line-item it so you see exactly what the Toto costs versus the plumbing labor.
What drives the range is the rough-in correction. A 12-inch rough-in with a standard Drake installs fast. A 10-inch or 14-inch rough-in, or a wall-hung model needing a carrier, adds labor and sometimes a plaster repair. In Thousand Oaks, where many homes sit on post-tension slabs, moving a drain line can be more involved than in a crawlspace home. We deliver a written price before any work starts. That price includes parts, labor, and our 365-Day Done Right Promise: if the work isn’t right within a year of completion, we make it right at no cost to you.
DIY or Call Us?
If you’re swapping a fill valve or flapper on a Toto that’s already working but running, that’s a reasonable DIY job. Turn off the angle stop, drain the tank, and follow the instructions. Toto parts are well-engineered, and the aftermarket alternatives are easy to match. Where it goes wrong is with the bowl-to-floor connection. Setting a toilet wrong, even by a quarter inch, creates a leak that won’t show for months, and by then the subfloor is wet. That’s not a lesson worth learning on a new $90,000 ADU bathroom.
Also not DIY: wall-hung carriers, anything involving moving a flange, and any project where the floor isn’t perfectly level. If you’re unsure whether your Thousand Oaks floor can handle a Toto without rocking, call us at (805) 309-3386. We’ll come out, check the flange height and the rough-in, and tell you exactly what it costs to do it right.
FAQs

A well-maintained Toto toilet lasts 15 to 25 years, with the fill valve and flapper needing replacement every 5 to 8 years in Thousand Oaks’ hard-water areas. The ceramic itself rarely fails; it’s the moving parts that wear. Call (805) 309-3386 for a free estimate on Toto replacement or repair.
Yes, most Toto failures are repairable. A running toilet is almost always a $25 to $60 part. Cracks, a rocking flange, or a bowl that’s scaled beyond cleaning point toward replacement. We’ll tell you honestly which way to go and put the price in writing before any work starts.
A straightforward Toto swap in Thousand Oaks takes about 2 to 3 hours from shutoff to haul-away, including disposal of the old fixture. If the rough-in needs correction or the floor needs leveling, plan for a full day. Call (805) 309-3386 for a written quote.
Yes, our Thousand Oaks crews carry Toto fill valves, flappers, gaskets, and supply lines as standard stock. For specific Washlet parts or less common models, we order genuine Toto parts and schedule the repair once they arrive. You’ll know the timeline before you commit.
Tell me what you need done. We’ll tell you what it costs and how long it takes, then we’ll do exactly that. Call Mason Remodeling Co Thousand Oaks at (805) 309-3386 for a free estimate on your Toto home addition or ADU project. Isaac Pruett and our crew have been serving Thousand Oaks for years, from whole-home renovations near Lang Ranch to smaller kitchen and bath builds, and we stock professional-grade Toto, Kohler, Moen, Grohe, KraftMaid, Cambria, and Silestone products for every job.
Written by Isaac Pruett, Owner, Mason Remodeling Co – Thousand Oaks, CA at Mason Remodeling Co Thousand Oaks, serving Thousand Oaks and nearby areas.


