Toto Home Additions & ADU Nationwide

Toto Home Additions & ADU: The San Jose Owner’s Guide

We stock and install Toto-compatible fixtures for home additions and ADU projects across San Jose. A full home addition with Toto fixtures typically runs $53,100 – $153,400 installed, while a standalone ADU with Toto plumbing runs $106,200 – $259,600. You’ll usually discover a failed Toto part the hard way: a fill valve that won’t stop running, a flush tower gasket that started weeping at 2 a.m., or a skirt bolt that stripped during an attempted DIY repair. We carry the common Toto replacement parts on our trucks, so if you’re in Willow Glen, Almaden Valley, or Evergreen, we can often get you sorted in a single visit. Penhallow Remodeling San Jose is an independent service provider and not affiliated with Toto, but we’ve installed and repaired enough of their products across San Jose to know exactly which parts fail and which ones hold up.

Call (669) 274-2362

Which Toto Models This Applies To

Toto’s parts are not one-size-fits-all, and that’s the first compatibility gotcha most San Jose homeowners run into. The flush valve tower on a Drake II is not the same height as the one in an Ultramax II, and the fill valve diaphragm for the original Drake with the 3-inch canister is a different animal from the 2-inch flapper setup in an older Toto Promenade. Before you order anything, flip the tank lid and look for a model number stamped inside the tank, usually starting with an “ST” prefix or “CST” followed by three digits. The other identifier worth checking is the fill valve brand: newer Toto bowls ship with a TSU-series valve, while older units may have a Korky or Fluidmaster retrofit already installed by a previous plumber. We always match OEM Toto parts where the spec matters (flush towers, gaskets, trip levers), but honest aftermarket equivalents from Korky work fine for fill valves and flapper-style applications. The one area we never substitute aftermarket: the G-Max and Dynamax tower assemblies. The tolerances there are tight enough that a generic copy causes ghost flushing or a slow leak into the bowl within a few months.

Signs Your Toto Home Additions & ADU Is Failing

• Constant hissing or running water. The fill valve diaphragm has worn out or debris from San Jose’s hard water has lodged in the seat. Toto’s TSU-series fill valves are rebuildable, but the retaining clip usually snaps after year seven or eight of mineral buildup, and that’s when you replace the whole valve.
• Ghost flushing in the middle of the night. The flush tower gasket has developed a slow leak. Water seeps past it until the level in the tank drops low enough to trigger the fill valve, which then makes you think the toilet is haunted. It’s the gasket, every time.
• Water weeping around the tank-to-bowl junction. The tank gasket has compressed or cracked, often after a decade of heat cycling in a San Jose garage ADU or uninsulated wall cavity. If you see corrosion on the bolts, the gasket has been failing for a while.
• Weak or incomplete flush. This usually points to clogged rim jets or a worn flapper/tower that isn’t lifting fully. Hard water scale from San Jose’s municipal supply can choke the rim jets faster than you’d expect, especially on models without Toto’s CEFIONTECT glaze.
• Condensation puddling on the floor. A cracked or pinholed overflow tube inside the tank can leak invisibly. You’ll see water on the floor, assume it’s the wax ring, and find out after replacing the ring that the tank internals were the culprit all along.

Replacement Cost & What’s Included

For a Toto fixture replacement or repair inside an existing San Jose bathroom, expect to pay $300 – $900 for a fill valve, flush tower, and gasket replacement, labor included. If you’re adding a full bathroom to a new home addition, the Toto fixture line-item runs $1,000 – $2,500 per toilet depending on model, and a complete bathroom addition with Toto fixtures lands in the $10,620 – $33,040 range. The difference usually comes down to access: if we’re opening a wall to replace a rough-in valve during an addition, we’re already there, so labor overlaps. If we’re swapping a fixture in a finished bathroom, we’re protecting floors, working around existing finish lines, and sometimes cutting tile, which drives the number up. Every installation comes with our written price before work starts, and our 365-Day Done Right Promise covers the workmanship. If the fixture fails inside that guarantee window, we come back and fix it at no charge. That’s in writing, on every job.

DIY or Call Us?

Most Toto toilet internals are genuinely DIY-friendly, and we’ll tell you that straight. A fill valve swap is a fifteen-minute job with a sponge and a bucket. What goes wrong is when an owner starts removing tank bolts without knowing the porcelain has hairline cracks, or cross-threads a plastic shank bolt on a skirted Toto and turns a $12 part into a cracked tank that costs $400 to replace. The other honest wrinkle: Toto’s skirted models hide the bolts under a plastic skirt, and if that skirt’s been snapped on for a decade in a San Jose garage that hits 90 degrees every August, it’s brittle. We’ve seen too many cracked skirts from well-meaning DIY jobs. Give me the real problem and I’ll give you the real number. If you’re not sure what’s actually failing, call us at (669) 274-2362 and describe the symptom. We’ll tell you over the phone whether it’s worth your time to do it yourself or whether it’s time for us to come out. Either way, you’ll get a straight answer.