Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Granite Bay
Most home additions and ADU projects in Granite Bay run between $45,000 and $130,000, with detached ADUs typically landing higher once you factor in the granite that sits just under the topsoil east of Auburn Folsom Road. We’re Barrett & Sons Construction, and we’ve been helping Granite Bay homeowners plan and build room additions, second-story expansions, garage conversions, and detached ADUs that actually pencil out against the local excavation and permit realities. Tom Barrett and his sons run our crews, and they know what happens when a foundation dig in this community hits solid rock at 24 inches. Call (877) 610-1318 and we’ll give you an honest read on your property before you spend a dollar.
Why Barrett & Sons Construction Is Granite Bay’s Preferred Home Additions & ADU Company
We’re not a franchise and we’re not a sales office that hands your job to whoever answers the phone that week. Barrett & Sons Construction was founded in 1998, and Tom Barrett’s name, address, and license number are published and verifiable. Ask anyone on your street, or look up the license number yourself.
Granite Bay homeowners tend to be thorough. They ask about change orders, they ask about allowances, they ask what happens when the county inspector finds something behind the drywall. We like that. Every scope, every allowance, and every price change on a Granite Bay addition or ADU arrives as a written change order before work happens. The allowance that isn’t on paper is a surprise waiting for a date, and we don’t do surprises at the final invoice.
Our crews are Tom’s sons and their teams, background-checked and uniformed on every visit. A live person answers our phone 24 hours a day, seven days a week. When you call about your Granite Bay ADU, you’re not leaving a voicemail for an out-of-state call center.
Our Home Additions & ADU Services in Granite Bay
We serve Granite Bay homeowners who need more square footage without moving. Here’s what we handle most often, and how the local terrain affects each one.
ADU Design & Permitting
Our Home Additions & ADU team handles the full design and permit package for Granite Bay accessory dwelling units. Since Granite Bay sits in unincorporated Placer County, every permit runs through the county building department rather than a city hall. That adds a review layer most regional contractors don’t plan for, and it means your drawings need to be right the first time. We pull permits on every eligible job, because the permit inspector works for you, not for me, and that’s why I like him.
Garage Conversion ADU
Granite Bay’s housing stock leans heavily toward custom estates built from the mid-1980s through the 2000s, and a lot of those homes have detached garages or oversized workshops that convert beautifully into living space. A typical garage conversion ADU in Granite Bay runs $30,000 to $80,000. The catch: converting a 1990s garage into a legal dwelling means bringing the wiring, insulation, and egress up to current Placer County code - and we handle that with inspection first, then a written plan, then a written price.
New Detached ADU
A new detached ADU in Granite Bay typically costs $90,000 to $220,000, and excavation is the wildcard that doesn’t exist in Roseville or Rocklin. On the established streets east of Auburn Folsom Road, our crews routinely hit granite ledge at 18 to 36 inches. That turns a one-day foundation dig into a multi-day rock-breaking operation, and we carry that contingency as a line item in every Granite Bay ADU proposal - not as a surprise later. We also manage ADU site prep and utilities, including trenching for water, sewer, and power where rock needs to be broken through.
Junior ADU & Interior Conversion
Junior ADUs - typically a bedroom with a small kitchenette carved out of an existing floor plan - are the fastest and least expensive way to add rentable or family space in Granite Bay. Interior conversions don’t face the same granite excavation costs as detached builds, but they do trigger the same county permit review and the same requirement for egress, ventilation, and fire separation we bring up to code before drywall goes back on. Second-story additions fall into this category too, and Granite Bay’s large stucco-and-tile estates often have the structural capacity for a second floor if the load path is checked by an engineer first.
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 Granite Bay
We don’t install mystery brands off a van. On Granite Bay additions and ADUs, we build with materials you can look up: GAF roofing underlayment and shingles for any new roof sections, Schluter waterproofing systems in ADU bathrooms and kitchens, and Grohe fixtures where the spec calls for them. We keep a working inventory of the parts and trims that Granite Bay remodels and ADU builds use most, so we’re not waiting on a freight truck when your shower rough-in or roof tie-in is ready to close up.
Common Home Additions & ADU Problems We See in Granite Bay Homes
We’ve worked on enough Granite Bay properties to know what hides behind the walls of a 1990s custom build. Here’s what we find most often.
- Cloth-wrapped wiring that won’t carry a modern ADU load. Older Granite Bay custom homes often have original branch wiring that predates today’s panel demand. When we tie in an ADU, the county inspector checks the whole path, not just the new wires.
- Framing that was never designed for a second story. Granite Bay estates look substantial, but some truss systems were sized for a single-story footprint. Before any second-story addition, we bring in a structural engineer to check the load path and write the fix into the allowance if one is needed.
- Garage slabs poured without vapor barriers or proper depth. Converting a 1980s or 1990s Granite Bay garage into an ADU often means cutting the slab for plumbing and finding a 3-inch slab on uncontrolled fill. We plan for that in every garage conversion quote, not after the saw is running.
- Excavation being underestimated entirely. This is the big one in Granite Bay. A contractor who doesn’t know the bedrock under this town quotes a standard dig, hits granite at two feet, and stops work when the budget dies. We quote Granite Bay ADU and addition foundations with the rock factor already on paper, so your schedule doesn’t stall in the middle of the job.
On a detached ADU job in a Granite Bay neighborhood off Auburn Folsom Road, our crew opened the existing garage wall to tie in new electrical and found cloth-wrapped wiring and a subpanel rated for half the load the new ADU required. We brought the rough-in up to current Placer County code, added a dedicated panel and ground-fault protection, and wrote the upgrade into a written change order before any additional work - so the client approved the exact cost before we proceeded.
Pricing for Home Additions & ADU in Granite Bay, CA
Here’s what you can expect to budget for the most common Home Additions & ADU projects in Granite Bay, based on current local market conditions and the rock excavation realities of this community. These are real ranges we quote from, not bait numbers meant to get a salesperson in the door.
| Project Type | Typical Granite Bay Price Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion ADU | $30,000 - $80,000 |
| Room Additions | $45,000 - $130,000 |
The two factors that move a Granite Bay quote more than anything else are bedrock during excavation and what the permit triggers once walls are open. You can plan for both. We walk the property first, write the scope, write the allowances, and write the rock contingency before we ask you to sign. Call (877) 610-1318 to schedule your free estimate - every quote is in writing, and every number is broken down line by line.
We Also Serve Cities Near Granite Bay
Our Granite Bay crews work throughout the surrounding area, including Orangevale, Loomis, Folsom, and Rocklin. If you’re in one of those communities and planning a home addition or ADU, the same written change order policy, the same permit-first approach, and the same Barrett & Sons name on the truck applies. We dispatch and schedule from our Sacramento office, and our crews serve Granite Bay locally.
Serving Granite Bay, CA - Our Local Coverage Area
We’re based in the Granite Bay 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 - Home Additions & ADU in Granite Bay
In Granite Bay, granite ledge under the topsoil east of Auburn Folsom Road routinely sits at 18 to 36 inches deep, which means a standard ADU foundation trench or utility dig often turns into a multi-day rock-breaking operation that adds several thousand dollars to the job. A knowledgeable Granite Bay contractor quotes that as a written contingency before breaking ground. Call (877) 610-1318 and we’ll walk your lot and tell you what to expect before you commit to a design.
Granite Bay is unincorporated Placer County, so all building permits for additions, ADUs, and garage conversions run through Placer County’s building department rather than a local city hall. That adds plan-review steps and county inspection dates to your schedule, and it’s why we pull every permit and schedule every inspection before the work starts - not after the walls are open. Call (877) 610-1318 and we’ll map out the full county process for your specific project.
In Granite Bay homes from that era, we typically find one of three things: cloth-wrapped or undersized wiring that won’t carry a modern ADU load, framing that was never sized for a second-story addition, or garage slabs poured too thin and without vapor barriers for a legal conversion. We identify all three during the inspection phase and write any fix into the contract as an allowance before work starts. Call (877) 610-1318 for a free estimate that accounts for these conditions up front.
Yes. Granite Bay sits in a CAL FIRE High Fire Hazard Severity Zone, so new detached ADUs and any re-roofing that accompanies a home addition must comply with Wildland-Urban Interface (WUI) material and ember-resistance standards that go beyond what’s required down in the Sacramento Valley. We spec WUI-compliant roofing, ember-resistant vents, and defensible-space-compatible materials on every Granite Bay build. Call (877) 610-1318 and ask us to review your ADU design against the current WUI requirements.
Every change order is issued in writing before any scope change touches the job. If we open a Granite Bay wall and find wiring that won’t pass a county inspection, or dig a trench and hit granite ledge sooner than expected, we write the exact fix, the exact allowance, and the exact price on a change order, and you approve it before we proceed. Nothing is billed as a surprise at the end. Call (877) 610-1318 to discuss your addition or ADU, and we’ll show you exactly how that works on paper.
Get Your Granite Bay Home Addition or ADU Estimate in Writing
If you’re planning a home addition, second-story expansion, garage conversion, or detached ADU in Granite Bay, call Barrett & Sons Construction before you sign anything. We’ll walk the property, check the granite risk, review the Placer County permit path, and give you a free written estimate with every allowance and every rock contingency already on paper. Tom Barrett’s name is on the truck and on the contract, and our 90-Day Done Right Promise backs every job. Call (877) 610-1318 today to schedule your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Granite Bay since 1998.