Fast, Reliable Bathroom Remodeling Across Los Serranos
A bathroom remodel in Los Serranos, CA typically runs $18,000 – $48,000 for a full gut-and-rebuild, with shower-only or guest-bath refreshes landing between $9,000 and $16,000 depending on the fixtures and waterproofing scope. Our crews work throughout the 91709 ZIP, from the neighborhoods around Los Serranos Country Club to the ranch-era parcels along Butterfield Ranch Road, and we scope every job with county-level permitting requirements baked in before quoting. If you own one of the 1970s – 1990s single-story ranch homes that define this pocket of unincorporated San Bernardino County, call (833) 863-7015 for a free, line-item estimate.
Why Guest House ADU Builders Is Los Serranos’s Preferred Bathroom Remodeling Company
Most of the bathrooms we remodel in Los Serranos sit inside homes built before modern plumbing and venting codes, which means the real work starts behind the tile. Our Bathroom Remodeling team has spent enough time in 91709 to know what’s behind those 1970s and 1980s ranch walls: galvanized supply lines, cast-iron drains, original panel wiring, and the occasional slab foundation that fights every new drain location. Homeowners here don’t call us for a simple fixture swap. They call us because adding a second bath or relocating a toilet on county land triggers a different review chain than the same project three hundred feet west in Chino Hills.
Nate Calloway built Guest House ADU Builders around a simple idea: the contractor who understands how a property actually works, including its septic capacity, county fire-access rules, and roofline venting constraints, is the one who gives you an honest number. That applied expertise shows up in the remodels we finish near the Country Club and the older horse-property lots off Butterfield Ranch Road. We do not treat your bathroom as a city permit job and hope nobody notices. We check the county requirements first, then price the tile.
Our reputation in Los Serranos rests on showing up with a plan that survives county inspection. That is the whole ballgame for unincorporated parcels. When the plumber, the tile setter, and the inspector all see the same scope in the same order, the job finishes on time. We are not a general remodeler doing a bathroom between kitchen jobs. We remap the plumbing, venting, and waterproofing to the actual conditions of a 91709 property, and we stand behind the workmanship warranty in writing.
Our Bathroom Remodeling Services in Los Serranos
Detached-ADU Bathroom Rough-In and Finish
A bathroom inside a detached ADU on a Los Serranos lot is a different animal from a main-house remodel. The county will review the connection to your existing septic system or sewer stub, the setback from the property line, and the fire-access route to the unit itself. We rough in the drainage, venting, and supply lines to meet San Bernardino County standards on the first pass, then finish with materials that hold up to inland foothill heat and Santa Ana wind events. If you are adding an ADU behind a ranch home near the Country Club, this scope often runs $14,000 – $28,000 depending on how far the trench has to travel.
Garage-Conversion Bathroom Build-Out
Converting a garage into living space with a new bath is a common pathway on Los Serranos lots where the main house sits on a slab and a detached structure already exists. The county reviews the conversion as a change of occupancy, which means the bath’s plumbing, ventilation, and fire separation get scrutinized. We handle the rough framing, the wet-wall plumbing, the waterproofing, and the exhaust venting with ember-resistant caps that pass fire-district inspection. A garage-conversion bath with shower, toilet, and vanity typically lands between $11,000 and $22,000 in 91709.
Second-Story or Addition Bath Tie-In Over Existing Low-Pitch Roofs
Many Los Serranos ranch homes have flat or very low-pitch roofs, which makes venting a new or relocated bath something you plan for, not something you improvise. We specify roof penetration details that survive wind-driven rain and ember exposure, and we size the exhaust fan to the duct run so the fan actually moves air instead of making noise. When we tie a new upstairs bath into a 1980s Mediterranean-style tract home, we also check the existing DWV stack and water pressure before demo starts, because older lines here were not sized for a second full bath. That pre-check has saved our clients from surprise change orders more times than we can count.
Full Hall-Bath or Primary-Bath Gut Renovation
The classic Los Serranos full bathroom is a 5×8 hall bath with a cast-iron tub, a single vanity, and a fan that has not moved air in years. We gut it to the studs, replace every supply and drain line, re-frame for a walk-in shower or a freestanding tub if the layout allows, and rebuild with waterproofing systems rated for the temperature swings this inland foothill climate dishes out. A full hall-bath renovation with mid-grade fixtures runs $16,000 – $26,000 on most 91709 ranch homes, with primary baths going higher when the scope includes a double vanity, curbless shower, and heated flooring.
What happens when you call
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A real person answersNo phone trees — you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Los Serranos
We work with plumbing fixture and waterproofing lines that are available locally and serviced by nearby supply houses, so Los Serranos homeowners are never waiting on a backordered valve or an obscure trim kit. In our bathroom remodels we regularly install Moen and Delta plumbing fixtures, Schluter and Wedi waterproofing systems, and James Hardie backer materials where exterior walls are involved. For ADU-adjacent work, we can coordinate the bathroom scope with a prefab shell from Mighty Buildings, Plant Prefab, or Tuff Shed, so the plumbing rough-in, the shower pan, and the finish work all line up with the manufacturer’s dimensions. That coordination is what keeps a prefab ADU’s bathroom from becoming an afterthought.
Common Bathroom Remodeling Problems We See in Los Serranos Homes
- Galvanized supply lines and cast-iron drains that have been patched repeatedly. The 1970s and 1980s ranch stock in 91709 often still has original plumbing. We replace everything back to the trunk line rather than patching over corrosion, because a new shower valve on a rusted galvanized stub is a callback waiting to happen.
- Septic and leach field capacity ignored until county review forces a change order. On unincorporated county lots, moving a toilet or adding a second bath can trigger a septic review. We verify tank size and leach field condition before demo, so the scope you sign is the scope that gets built.
- Bath exhaust fans vented into attics or through unrated roof caps. Los Serranos sits in a wildfire-risk zone with real Santa Ana wind loading. A cheap plastic roof cap fails, lets embers in, and rots the sheathing. We use ember-resistant vent assemblies and rigid duct on every remodel.
- Slab foundations that fight every new drain location. Many ranch homes here sit on slabs, so moving a toilet more than a few feet means cutting concrete. We map the drain paths and give you a hard number for slab work before you pick out the tile, not after the jackhammer shows up.
Pricing for Bathroom Remodeling in Los Serranos, CA
A guest-bath refresh with a new tub, surround, toilet, and vanity in Los Serranos runs $9,000 – $16,000. A full hall-bath gut with a walk-in shower conversion lands between $16,000 and $26,000. A primary-bath remodel with a curbless shower, double vanity, and heated floors starts around $28,000 and goes to $48,000 or more when the job includes moving walls or relocating the drain stack. The biggest cost drivers in 91709 are not the tile choices. They are the slab cutting, the septic review when you move a fixture, and the fire-rated venting and waterproofing the county requires. That is why our estimates are line-item and fixed. You will see every dollar before we start, and the number does not move unless the scope changes with your written sign-off. Call (833) 863-7015 for a free estimate on your Los Serranos bathroom.
We Also Serve Cities Near Los Serranos
While most of our bathroom remodels happen right here in Los Serranos, our crews also run jobs in Chino, Yorba Linda, Montclair, and Pomona. The county-level permitting process in 91709 is not something we have to learn on your dime. If you are just over the line in Chino or Montclair, the review process changes, and we adjust the scope accordingly.
Serving Los Serranos, CA — Our Local Coverage Area
We’re based in the Los Serranos area and know this community well. Use the map below to see our service coverage — if you’re nearby, we can almost certainly help.
FAQs – Bathroom Remodeling in Los Serranos
Yes. Los Serranos is unincorporated San Bernardino County land, so a bathroom remodel that changes the footprint, adds a fixture, moves a drain, or touches the septic connection goes through county review rather than a Chino Hills city permit. A simple like-for-like fixture swap on existing rough plumbing may only need a plumbing permit, but any change to the drainage or water supply lines gets county eyes on it. We route every remodel through the correct agency before work starts and handle the inspection scheduling for you. Call (833) 863-7015 and we will tell you exactly which review your project triggers.
You can, and many of those large ranch-era lots have the space to do it well, but the county will review your septic tank capacity and leach field condition before signing off on a second bathroom. On older parcels off Butterfield Ranch Road, the existing septic may have been permitted for a two-bedroom house and never upgraded. We pull that record, verify the tank and field, and get the county sign-off before we cut into any slab. That up-front verification is what keeps a second-bath addition from becoming a mid-demo surprise. Call (833) 863-7015 for a scope and price on your lot.
Because Los Serranos sits in an inland foothill fire-risk zone with real Santa Ana wind loading, the roof penetration and vent assembly have to meet a tougher standard than a coastal county would require. We use ember-resistant caps, rigid duct, and heat-rated fan housings rated for the attic temperatures this area sees in August. On older low-pitch roofs, we also add a site-fabricated curb and flashing detail that a standard off-the-shelf cap will not pass. It is an extra few hundred dollars on most jobs, and it is the difference between a bath fan that works for twenty years and one that fails at year three.
We rough in the bathroom to county plumbing and fire-access standards, and we coordinate the drain and vent paths with the unit’s footprint before the walls close. For a detached ADU on a Los Serranos parcel, the county checks the setback, the septic or sewer connection, and the fire apparatus access route to the unit, so the bath plumbing has to be planned around those constraints, not after the shell is up. When the unit is a prefab from one of the brands we work with, the bathroom rough-in gets matched to the factory dimensions so the finish work is clean. Call (833) 863-7015 for a detailed breakdown on your ADU or garage-conversion bath.
Expect galvanized supply lines, a cast-iron drain that has been patched at least once, and original wiring that is not GFCI-protected by modern standards. On a typical 1970s ranch home near Los Serranos Country Club, the original waterproofing behind the tub surround is often drywall with a plastic sheet, not a modern cement board and membrane system. None of that is a reason to avoid the remodel. It just means the quote has to include replacement of those systems, not a cosmetic overlay. We show you what we found with photos and give you a revised line item before we proceed, never after the work is done.
Written by Nate Calloway, Owner at Guest House ADU Builders, serving Los Serranos and the surrounding unincorporated San Bernardino County foothill communities.