Licensed Design-Build Contractor
Engineered for your exact lot, permitted through the City of Sunnyvale. Studios to full three-bedroom homes, designed around the shape of your property and the house already standing on it.
Custom detached ADUs from $165,000 · CSLB #1130783
Our 1,000 sq ft three-bedroom model. In Sunnyvale a new construction ADU above 800 sq ft goes through a Miscellaneous Plan Permit before the building permit, which is a path we handle routinely.
Sunnyvale recognises four kinds of accessory dwelling unit, and which one you are building decides how the City reviews it, how big it can be, and how long it takes to get approved. Most homeowners find that out after they have paid for a design.
A standalone unit built in your yard. Full independence from the main house, the highest rental value, and the most design freedom because you are not working around an existing structure. All six of our ADU models are detached new construction.
New square footage built onto the existing house, sharing at least one wall. Useful on lots too tight for a detached unit, though it comes with its own size limits tied to the primary dwelling and less separation between households.
Existing space turned into a dwelling. A garage, a rear structure, or part of the house. Usually the least expensive route because the shell exists, though you give up the garage and inherit whatever the original construction left behind.
Up to 500 sq ft created by converting part of the existing or proposed single-family home, with its own entrance and an efficiency kitchen. The smallest and simplest option, and it can sit alongside a full ADU on the same property.
Our six models are all detached new construction. Sunnyvale allows the other three types, and we build them, but attached units, conversions and JADUs follow different design and permitting rules and are quoted as custom projects rather than from the model line.
This is the part that matters most for an ADU builder Sunnyvale homeowners are choosing between, because it changes your timeline before anything is drawn.
New construction ADUs up to 800 sq ft on a single-family lot. Also covers all new construction ADUs on multifamily lots, conversion ADUs, JADUs, and ADUs entirely within a new basement.
No Planning permit required. You go straight to the building permit.
A new ADU larger than 800 sq ft on a single-family lot. You apply for a Miscellaneous Plan Permit first, and the Planning Division reviews it to confirm the project meets City standards.
Only after the MPP is approved can the building permit be submitted. It is a real step with its own review, and it belongs in the schedule from week one.
| Standard | Sunnyvale Requirement |
|---|---|
| Units on a single-family lot | Up to three: one new construction ADU, one conversion ADU, and one JADU |
| One combination not allowed | A lot cannot have both a conversion ADU inside the main building and an attached new construction ADU |
| JADU exception | Not permitted on lots with two or more detached single units |
| Streamlined size threshold | 800 sq ft for new construction on a single-family lot |
| Attached ADU | Cannot exceed 50% of the existing primary dwelling |
| Junior ADU (JADU) | 500 sq ft maximum, converted from the existing or proposed home |
| Side and rear setbacks | Four feet minimum for new construction |
| Conversion setbacks | Less than four feet allowed where the unit stays in the same location and dimensions as the existing structure |
| Detached height | 16 feet, measured from average finished grade within five feet of the structure |
| Second story ADU | Only permitted above the primary dwelling |
| Front yard | Detached ADUs are not permitted in the front yard |
| Parking | None required for a new ADU. Replacement parking not required when a garage is converted |
| Owner occupancy | Not required |
| Rentals | Long term only. Short-term rental is not permitted |
You may be allowed three units, not one. On an eligible single-family lot Sunnyvale permits a new construction ADU, a conversion ADU and a JADU. Most homeowners assume the limit is one, and plan the property around a ceiling that is not actually there.
The 800 sq ft line is a schedule decision, not just a size one. Going to 1,000 sq ft is entirely buildable, but it moves you onto the Miscellaneous Plan Permit path and adds a Planning review ahead of the building permit. Worth deciding deliberately rather than discovering at submittal.
Entrances cannot share a wall plane facing the street. The ADU needs separate independent exterior access, and its entrance and the primary dwelling's entrance cannot sit on the same street-facing plane. That is a siting constraint, and it is far easier to design around than to fix.
Standards published by the City of Sunnyvale — Accessory Dwelling Units, with the full regulations in Chapter 19.79 of the Sunnyvale Municipal Code. Requirements change and depend on your zoning district and property conditions, so we confirm what applies to your specific parcel before design begins.
Six floor plans, each one a starting point we customize to your lot. All six are detached new construction. Every price below is a real starting number, not a teaser rate that climbs once you are committed.
Every model comes in two exterior styles with the identical floor plan. Which one belongs on your property usually comes down to your existing home, because a Sunnyvale Eichler and a postwar ranch call for very different treatments. The ADU should read as part of the property rather than something dropped behind it.
Our most efficient unit, and the fastest route to rental income on a tight Sunnyvale lot. Well under the 800 sq ft streamlined threshold and under the 500 sq ft school fee line.
Floor Plan & Details
A true one-bedroom with French doors to the yard. Deliberately held under 500 sq ft, which keeps it clear of the school impact fee threshold entirely.
Floor Plan & Details
Two bedrooms without going full size. Stays under 750 sq ft, which keeps it clear of the transportation impact fee while still renting as a two-bedroom.
Floor Plan & Details
Two bedrooms, two full baths, one ensuite. The largest model that still clears Sunnyvale's streamlined path, which makes it the sweet spot on most lots here.
Floor Plan & Details
Three bedrooms, and it lives like a house rather than an add-on. Above 800 sq ft, so it goes through a Miscellaneous Plan Permit before the building permit.
Floor Plan & Details
Our largest model, with a primary suite and private patio. Also on the plan permit path, and worth confirming against your lot's zoning and coverage before design.
Floor Plan & DetailsWant a size that is not on this list? We draw it custom. These plans exist because they cover what most Sunnyvale lots need, not because they are the only thing we build. For the full regional picture, see our ADU builder Bay Area page and the complete ADU cost breakdown.
Straight talk on pricing. Our starting-from numbers cover far more than the build itself, and everything outside them is named here, before you sign, rather than discovered in month four.
Through our showroom partners across the Bay Area, we help you select every finish material, flooring, cabinets, countertops, tile and fixtures, and have it delivered directly to your project on our construction schedule. All the choice, none of the logistics.
Every item above is broken out in a line-item proposal before you sign anything. You will know exactly what you are paying for and where it goes, in writing, before a single wall goes up.
Most Sunnyvale homeowners financing an ADU hit the same problem. A standard home equity loan lends against what your property is worth today, not what it will be worth with a second permitted dwelling on it. That gap is what stops good projects before they start.
We partner with RenoFi, which lends against your home's after-renovation value, so your borrowing power reflects the finished property rather than the current one. It works across everything we build, from a Sunnyvale kitchen remodel to a bathroom remodel to a custom ADU.
Check If You QualifyBuilding more than one space? Beyond ADUs we handle kitchen remodels, bathroom remodels, home additions and whole home remodeling throughout Sunnyvale. Browse the full range of design-build services.
Permit and impact fees go directly to the City of Sunnyvale and the applicable districts. We never mark them up and we never take a cut. What we do is tell you which ones apply to your project before you commit to a size.
Charged by the City based on the size and type of the ADU. A 350 sq ft studio and a 1,200 sq ft three-bedroom are not the same permit, and neither are a conversion and new construction. This is the base charge before anything else applies.
Applies only to new construction ADUs above 800 sq ft on a single-family lot. It is a separate Planning application with its own fee, submitted and approved before the building permit can go in.
Water, sewer and electrical. Whether the ADU needs its own meter, how far the connections have to run, and whether any work falls in the public right-of-way all change this number. It is the line that moves most between two otherwise identical projects.
Included in the City's permit charges rather than billed separately, but worth knowing they cover multiple review rounds and every inspection through final sign-off.
New construction ADUs of 500 sq ft or more are subject to school impact fees. These are set and collected by the school district serving your property, not by the City, and proof of payment is generally required before a building permit is issued.
ADUs above 750 sq ft are subject to a transportation impact fee. State law exempts ADUs under 750 sq ft from local impact fees, which is exactly why that threshold exists and why it is worth knowing before you settle on a size.
This is where model selection stops being about layout. Our 499 sq ft one-bedroom clears both thresholds. The 650 sq ft two-bedroom owes school fees but stays under the transportation line. The 800 sq ft two-bedroom owes both, and above it you add the Plan Permit as well. None of that makes a bigger ADU the wrong choice. It just belongs in the conversation before you pick one, not after.
Sunnyvale offers a free ADU Calculator that gives a rough estimate of costs, fees and rents for your property. It is a genuinely useful starting point, and we would rather you run it than take any contractor's word for a number, ours included.
Sunnyvale does not publish a single all-in ADU permit price, because there is not one. The building permit depends on size and type, the Plan Permit applies only above 800 sq ft, the school fee starts at 500, the transportation fee starts at 750, and utility connection costs depend on your property.
That is why we never fold permits into a headline price. You would have no way to tell what you were actually paying for. Instead we identify every fee that applies to your specific project during the free consultation and put them in the proposal as separate line items, at cost.
Permit paths and ADU types published by the City of Sunnyvale, which also publishes an ADU Toolkit covering the process end to end. Fees are set by the City, the applicable school district and other agencies, and are subject to change. School impact fees are set by the school district serving your address, not by the City. We confirm current figures for your property before your budget is finalised. For how Sunnyvale compares regionally, see our ADU builder Bay Area page and the Bay Area ADU cost guide.
This is the whole reason most Sunnyvale homeowners build. An ADU is not extra space, it is an income-producing asset on land you already own, in one of the strongest rental markets in the country.
The left column is the Sunnyvale apartment market as of September 2026. The right column is what we would actually plan around for a detached backyard ADU, and it sits deliberately below the apartment number.
| Unit | Sunnyvale apartment average | ADU planning range |
|---|---|---|
| Studio | $2,773 / month | $2,300–$2,600 |
| 1 Bedroom | $3,188 / month | $2,700–$3,000 |
| 2 Bedroom | $4,065 / month | $3,300–$3,700 |
| 3 Bedroom | $4,876 / month | $3,900–$4,400 |
Why the ADU number is lower. A detached backyard unit has no gym, no pool, no parking structure and it shares a lot with the main house. It still commands a premium in Sunnyvale because of where it sits, but planning around the apartment average would be planning around the wrong number. Actual rent depends on unit size, finish level, privacy, parking and your specific block, and we pull live comps for your address during the consultation.
Read that honestly. It is gross yield on build cost alone. It does not account for permit and impact fees, financing costs, property tax on the new square footage, vacancy or maintenance, all of which are real. Net returns land meaningfully lower. What the number shows is the scale: roughly $39,000 a year against land you already own, which is why an ADU competes with almost any other use of the same capital.
A legal, inspected ADU adds documented living area to your property. That is square footage an appraiser counts and a buyer pays for. Unpermitted work does the opposite and can block a sale outright.
Monthly rent while you hold it, and a higher number when you sell. Most improvements give you one or the other. An ADU is among the few that reliably gives you both in a market like this one.
Not every homeowner builds for a tenant. Plenty of the ADUs we build house a parent who wants to stay close, or an adult child priced out of the local market. The financial case still holds. You are housing family at zero rent instead of paying Sunnyvale rates elsewhere, and the property value is there either way.
Apartment averages reflect Sunnyvale market rents as of September 2026. ADU planning ranges are set below them because a detached backyard unit is not a full-amenity apartment building. Rental markets move, and we verify against live listings for your address. The City of Sunnyvale also publishes a free ADU Calculator that estimates rents alongside costs and fees.
What decides your timeline is not the City's speed. It is how complete your submittal is when it goes in, and whether your project needs a Planning permit before the building permit.
California law requires a permitting agency to approve or deny a completed ADU application within 60 days. That protection is real and worth knowing.
But the clock only starts when the submittal is complete, and 60 days is the statutory limit on review rather than the total time to permit. Sunnyvale's own ADU Toolkit puts the overall permitting phase at roughly one to six months depending on complexity and how many reviews a project needs.
We publish the range rather than the statute, because the range is what you should budget around.
Before anything is drawn we walk the property, confirm setbacks and height against your parcel, check where the unit can physically sit, and determine whether your project clears Sunnyvale's streamlined path or needs a Miscellaneous Plan Permit. That single answer shapes the entire schedule.
3D design, full blueprints and elevations, Title 24 energy calculations, CALGreen documentation, structural engineering and property survey. Everything is dimensioned against the review path we identified in step one, so the drawings, the calculations and the site plan all say the same thing when they reach a reviewer.
If your ADU is larger than 800 sq ft on a single-family lot, this comes first. The Planning Division reviews the application to confirm the project meets City standards, and only once it is approved can the building permit be submitted. Projects at or under 800 sq ft skip this step entirely.
Plans are uploaded through the City's online permit system. Building, Fire and Public Works each review. Comments come back, we respond and resubmit. A clean, complete set clears in far fewer cycles than an incomplete one, and this is the part we are paid to get right the first time.
Privacy fencing, portable restroom, dumpster, and a walk of the property with you first to see what landscaping is worth saving. Utility coordination runs in parallel, including any separate metering the project requires.
Foundation through finishes, with a City inspector signing off at every stage. If your project requires fire or Public Works inspections, those are run separately by each department. Your dedicated project manager coordinates all of it.
The building permit is finaled and occupancy granted once construction is complete and the final inspection passes. We bring in a professional crew for a full clean inside and out, then walk the finished ADU with you.
From first consultation to keys, for a new construction ADU in Sunnyvale. A conversion runs shorter, and a project above 800 sq ft runs longer because of the Plan Permit ahead of it. This is our own estimate built on the City's published review guidance and our construction schedules, not an optimistic number designed to win the job.
The variable you control is how many review cycles your submittal takes. A set drawn by someone unfamiliar with this city routinely goes through four or five rounds, and each one is weeks you do not get back. A complete, correctly dimensioned first submittal is the single biggest time saving available on an ADU.
The other variable has nothing to do with drawings. It is the supporting paperwork, the Title 24 calculations, the CALGreen documentation, the owner declarations. An incomplete package does not slow your review down, it stops it from starting. We request those in week one rather than week ten.
And if you are deciding between 800 and 1,000 square feet, the Plan Permit belongs in that conversation. Going bigger is entirely reasonable and we build it often. It just adds a review step ahead of everything else, and you should choose it knowing that rather than find out at submittal.
Permitting phase guidance published in the City of Sunnyvale ADU Toolkit and on the City's Accessory Dwelling Units page. The 60-day approval requirement is set in California Government Code §66317. Actual timelines vary with project scope, site conditions and how many review cycles an application requires.
A boutique, owner-led design-build firm based in San Jose, a short drive from Sunnyvale. You work directly with the people responsible for your ADU, from the first walk of your lot to the day we hand you the keys.
You deal directly with the owners, the same people from your first conversation to your final walkthrough. No handoff to a crew you have never met.
One point of contact who knows your project inside out, from first sketch to final punch list. No call centers, no explaining your job to a stranger every time you call.
Architect, engineer, permit submittal and construction all in-house. When something needs solving there is nobody to point at, and nobody charging you twice for a redesign that came back over budget.
We design and build on your lot, around your existing home. Every model is a starting point adjusted to your parcel, your setbacks and the review path that applies, not a factory box dropped in the yard.
The 800 sq ft streamlined threshold, the Plan Permit path above it, the school and transportation fee lines, the siting constraints. The reason those are published on this page is that we work with them.
A detailed proposal before you sign anything, with every item priced. The only thing that moves the number is a change you request or something genuinely unexpected, and either way you get a written change order first.
Your payment schedule is tied to completed construction, not our cash flow. California law caps what a contractor can collect before work begins and we follow it.
Professional clean inside and out, final inspection passed, occupancy granted, then we walk the finished ADU with you. Keys to a completed home, not a punch list to chase across four trades.
A fully licensed California general contractor. We are happy to provide our license and insurance documentation before you sign anything, and frankly you should ask that of every contractor you are considering. Verify any license in about thirty seconds at cslb.ca.gov. An ADU is permanent construction on your property, and the paperwork matters as much as the craftsmanship.
See the work rather than the claims. Our completed projects include ADUs, kitchens, bathrooms and whole home renovations across the Bay Area, and our homeowner testimonials come from the people who lived through the build. If you want to know who you would actually be working with, start with our story.
The questions Sunnyvale homeowners actually ask before they hire anyone, answered the way we would answer them standing on your property.
More than most homeowners expect. On an eligible single-family lot Sunnyvale permits up to three: one new construction ADU, one conversion ADU, and one JADU.
Two limits apply. A JADU is not permitted on lots with two or more detached single units. And a lot cannot have both a conversion ADU inside the main building and an attached new construction ADU.
On multifamily properties the numbers work differently again, based on the existing number of units. We confirm what your specific parcel allows during the first walk.
Only if the ADU is larger than 800 square feet on a single-family lot. That is the line, and it decides your schedule more than anything else.
At or under 800 sq ft, you are on the streamlined path and go straight to a building permit with no Planning permit required. Conversion ADUs, JADUs, ADUs entirely within a new basement, and all new construction ADUs on multifamily lots are also streamlined.
Above 800 sq ft you apply for a Miscellaneous Plan Permit first. The Planning Division reviews it to confirm the project meets City standards, and only after that approval can the building permit go in. It is a real step, not a formality, and we build it into the schedule from week one.
Our starting prices run from $165,000 for a 350 sq ft studio to $540,000 for a 1,200 sq ft three-bedroom, delivered turnkey. Those numbers include labor, rough materials, 3D design, full blueprints, Title 24, structural engineering, property survey and utility trenching up to 20 feet.
Priced separately and named before you sign: City permit and impact fees, finish materials, appliances, soil report if your lot needs one, special inspections, and any site-specific work like grading.
Two square footage lines matter for fees. School impact fees apply to new construction ADUs of 500 sq ft or more, paid to the school district rather than the City. A transportation impact fee applies above 750 sq ft. The City also publishes a free ADU Calculator that gives a rough estimate for your property.
Roughly 9 to 14 months from first consultation to keys for a new construction ADU. That breaks down as one to two weeks of feasibility, six to eight weeks of design and engineering, the permitting phase, four to five months of construction, and a couple of weeks for final inspection and handover.
The City's own ADU Toolkit puts the permitting phase at roughly one to six months depending on complexity and how many reviews a project needs. If your ADU is above 800 sq ft, add two to four weeks for the Miscellaneous Plan Permit ahead of the building permit.
The variable you actually control is how many review cycles your submittal takes. A complete, correctly dimensioned first set clears in far fewer rounds than one drawn by somebody unfamiliar with this city.
California Bay Builders & Remodeling is a licensed, owner-led design-build general contractor, CSLB #1130783, building custom ADUs across Sunnyvale and the Bay Area. Design, structural engineering, permit submittal and construction all run through one team with one project manager.
We start by walking your property and confirming which review path applies, because whether your project clears Sunnyvale's 800 sq ft streamlined threshold changes your schedule before a single line is drawn. Then we handle the full package the City requires so your submittal goes in complete the first time.
We build custom rather than prefab, designed around your lot and your existing home, and we hand off turnkey with the final inspection passed and the site professionally cleaned. Over 100 five-star reviews across platforms, three Best of Houzz Service awards, verified NKBA member, BBB accredited, licensed, bonded and insured.
Every lot is different, and the best answers come from standing on the property. We will walk your parcel, confirm what Sunnyvale allows on it, and give you real numbers before you spend a dollar.
Book a Free ConsultationIf you have the lot, we can build the ADU. Designed around your property, permitted through the City of Sunnyvale, and delivered turnkey by one owner-led team.
The consultation is free and there is no obligation. We walk your lot, confirm which review path applies and what the City allows on your parcel, and tell you honestly what it will cost before you invest a dollar in design.
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Beyond custom ADUs, we handle kitchen remodels, bathroom remodels, home additions and whole home renovations throughout Sunnyvale and the Bay Area. See our full range of design-build services or browse the Bay Area ADU program.
Building accessory dwelling units across Sunnyvale and the wider Bay Area. If your city has its own ADU page, you can open it below for local permit information, project details, and what to expect.
Do not see your city linked yet? We may still serve your area. Tell us where the property is and we will let you know what your city requires.
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