Everything you need to build an ADU in Mountain View — lot eligibility, size limits (850–1,000 sqft), the ePermitsMV permit process, utility requirements, and a full cost breakdown. No planning permit needed. All sourced from official City records.
Data verified 2026-08-18 · City of Mountain View · Mountain View Zoning Code Chapter 36 · CA HCD
Lot Eligibility
ADUs are permitted on all residential lots in Mountain View under California state law — with no planning permit required. Select your ADU type and zone below for results using verified City rules.
Mountain View Advantage: No Planning Permit Required
Unlike many Bay Area cities, Mountain View does not require a Planning Permit for ADUs. You go straight to a Building Permit — skipping weeks or months of discretionary planning review. This significantly reduces both timeline and cost compared to cities like Palo Alto or San Jose.
Instant eligibility check — Mountain View rules as of 2026-08-18
ADUs are allowed in R-1, R-2, R-3 zones and mixed-use zones where residential use is permitted. No minimum lot size. Both single-family and multi-family properties qualify.
California state law allows one detached ADU plus one JADU on the same single-family lot — giving you up to 2 additional dwelling units. No owner-occupancy required for the ADU (JADU requires owner-occupancy of primary or JADU unit).
Mountain View requires separate water, sewer, and gas connections for all ADUs, placed underground. Individual meters are advisable. Confirm property utility capacity before finalizing ADU design. Contact Building Division at (650) 903-6313 or Planning at (650) 903-6306 before finalizing your design.
ADU Types & Sizes
Mountain View allows four ADU types. Detached ADU size varies by bedroom count — 850 sqft for studio/1-bedroom, 1,000 sqft for 2+ bedrooms. State law guarantees a minimum of 800 sqft for attached ADUs the city cannot go below.
| Rule | Mountain View | Source |
|---|---|---|
| Max size — studio/1-bedroom ADU | 850 sqft | Mountain View Zoning Code |
| Max size — 2+ bedroom ADU | 1000 sqft | Mountain View Zoning Code |
| Side & rear setback (detached) | 4 ft minimum | CA Gov. Code §66332 |
| Separation from existing structures | 6 ft | Mountain View Zoning Code |
| Height — standard | 16 ft | Mountain View Zoning Code |
| Height — two-story (SB 897) | 28 ft | CA SB 897 (2022) |
| Planning permit required | None — Building Permit only | Mountain View ADU Program |
| Parking required | None | CA Gov. Code §66333 |
| School fee exemption | ≤500 sqft | CA SB 543 (Jan 2026) |
Permit Process
Permits are submitted online through ePermitsMV . Standard review runs 8–16 weeks; the pre-approved plan program targets ~30 days for qualifying plan sets. No Planning Permit is required.
No Planning Permit — Building Permit Only
Mountain View does not require a Planning Permit for ADUs — you go straight to a Building Permit. This skips weeks of discretionary planning review and makes Mountain View one of the most streamlined cities in the Bay Area for ADU permitting.
#1: Incomplete or inconsistent plan set
Misalignment between architectural, structural, and MEP sheets — or missing specifications — triggers multiple plan check correction cycles. A clean, coordinated first submission is the fastest path through ePermitsMV.
#2: Utility coordination not resolved early
Mountain View requires all ADUs to have separate utility connections (sewer, water, gas) placed underground. Inadequate utility capacity evaluation or plans that don't match existing infrastructure cause surprises mid-review.
Feasibility & Zone Check
Confirm residential zoning (R-1, R-2, R-3), setbacks (4 ft side/rear, 6 ft from existing structures on the lot), and lot coverage. No Planning Permit is required for ADUs in Mountain View — only a Building Permit. This is one of Mountain View's key advantages over other Bay Area cities.
Evaluate Pre-Approved ADU Plans
Mountain View's AB 1332 pre-approved plan program targets a ~30-day review. Visit https://developmentpermits.mountainview.gov/residential/accessory-dwelling-units/preapproved-adu-s to see available designs. If a pre-approved plan fits your lot, zHeight assembles the site-specific permit package around it — adding structural engineering, Title 24 CF1R, and utility plans.
Design & Engineering
Full permit-ready plan set: architectural drawings, site-specific structural calculations, separate utility connection plans (water, sewer, gas — all underground), and Title 24 CF1R energy compliance. Mountain View requires all ADUs to have separate utility connections, so these must be included in the submitted plan set.
Utility Capacity Verification
Mountain View requires all ADUs to have separate utility connections placed underground. Confirm sewer, water, and gas capacity for your property before finalizing plans — infrastructure surprises are a common delay cause. Individual meters are advisable for practical long-term management of both units.
Utility capacity issues are the #2 cause of permit delays in Mountain View. Verify before finalizing your ADU design.
Submit via ePermitsMV
Submit online at https://developmentpermits.mountainview.gov/. Track plan check status at https://epermits.mountainview.gov/pc.aspx. Standard: 2-week initial review, 2 weeks per resubmittal cycle — typically 8–16 weeks total. Pre-approved plans: ~30 days. zHeight handles the submission and monitors the portal for review status updates.
Permit Issued — Build
Pay permit fees, receive your building permit, and schedule required inspections (foundation, framing, rough MEP, insulation, final) through ePermitsMV. Building Division: (650) 903-6313. State approval clock: 60 days (ministerial — city cannot extend).
Mountain View requires separate water, sewer, and gas connections for all ADUs, placed underground. Individual meters are advisable. Confirm property utility capacity before finalizing ADU design.
Water
Separate connection required underground. Confirm capacity with Mountain View water provider before finalizing design.
Sewer
Separate sewer lateral required underground. Capacity confirmation needed — older properties may require infrastructure upgrades.
Gas
Separate gas connection required underground. Individual meters advisable for independent billing and management of both units.
This is the #2 cause of permit delays in Mountain View. Utility capacity evaluation and plans must be submitted with your Building Permit application. zHeight includes separate utility connection plans in every Mountain View permit package.
Cost Guide
ADU costs break into three buckets. City permit fees are valuation-based — verify current amounts with Building Division before budgeting. Impact fees: exempt under 750 sqft (state law); school fees exempt under 500 sqft (SB 543, Jan 2026).
$7,000 – $16,000+
zHeight flat-fee or custom quote. Includes architectural plans, site-specific structural calculations, separate utility connection plans, and Title 24 CF1R. Separate utility connections (required in Mountain View) are included in our scope.
Valuation-based
Mountain View uses a valuation-based permit fee table. Verify current amounts at https://developmentpermits.mountainview.gov/ or call Building Division at (650) 903-6313 before budgeting. ADUs under 750 sqft are exempt from general impact fees; ADUs 500 sqft or less are also exempt from school fees (SB 543, Jan 2026).
$300 – $500+ / sqft
Paid to your licensed general contractor — not zHeight. Detached ADUs typically run $200K–$500K+ total. Utility connection costs vary by property infrastructure. Get contractor bids after permit approval.
Fee Exemption Strategy for Mountain View
Build at 749 sqft or less to eliminate general impact fees statewide (CA Gov. Code §66324). Build at 499 sqft or less to also eliminate school impact fees (CA SB 543, effective Jan 1, 2026). Garage conversions with no new utility infrastructure required are exempt from all impact and connection fees. Verify current amounts at https://developmentpermits.mountainview.gov/ .
Verify Permit Fees Before Budgeting
The City of Mountain View uses a valuation-based permit fee table. Full details are available at the ePermitsMV portal. Call Building Division at (650) 903-6313 or Planning at (650) 903-6306 for current figures before you finalize your budget.
Want a cost estimate for your specific lot and ADU type?
Get a Free Project EstimateWhy zHeight
Mountain View's AB 1332 pre-approved ADU plan program is a genuine head start — targeting ~30-day review. Here's exactly what pre-approved plans include and what still requires site-specific work before ePermitsMV will accept your submission.
Pre-approved plans are a real option. Mountain View's AB 1332 pre-approved ADU plan program offers reviewed designs that qualify for the ~30-day fast-track review. Visit the pre-approved ADU page to see available designs. If a pre-approved plan fits your lot, zHeight can assemble the site-specific permit package around it — adding structural engineering, utility connection plans with in-house Title 24 CF1R included, and ePermitsMV submission — rather than starting from scratch.
| What you need | Pre-Approved Plans | zHeight Package |
|---|---|---|
| Plan drawings | Generic templates reviewed for a typical lot | Drawn specifically for your lot, setbacks, and configuration |
| Structural engineering | Generic calcs — may not match your soil or foundation | Site-specific structural calcs stamped by a licensed engineer |
| Utility connection plans | Not included — required for all Mountain View ADUs | Included — separate water, sewer, gas plans for ePermitsMV |
| Title 24 CF1R | Not included — required separately before permit is issued | Included in every permit package |
| ePermitsMV submission | You submit and monitor yourself | zHeight handles submission and portal monitoring |
| Plan check corrections | You respond to City correction letters | zHeight responds to all corrections until permit is issued |
The #1 cause of permit delays is an incomplete plan set at intake. zHeight's organized, City-compliant submission — all required sheets, utility connection plans, Title 24 CF1R included — avoids rejection before review even begins. Mountain View's separate utility requirement makes a complete submission especially critical.
zHeight provides architectural drawings, structural engineering, utility connection plans, Title 24 compliance, and permit processing. We coordinate with your chosen licensed General Contractor throughout — we do not perform construction or contracting.
FAQ
Common questions about ADU eligibility, zoning, setbacks, utility requirements, the ePermitsMV portal, and costs in Mountain View.
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Our Services
From a kitchen remodel to a full ADU build, zHeight handles the design, planning, and permitting. We work alongside your contractor — we are not the builder.
Design & permitting only. zHeight provides architectural drawings, structural engineering, utility connection plans, Title 24 compliance, and permit processing via ePermitsMV. We do not provide construction or contracting services. We coordinate with your chosen builder throughout the process.
Detached ADU, attached ADU, JADU, and garage conversion plans — permit-ready and ePermitsMV-compliant for Mountain View. Includes separate utility connection plans.
Layout changes, kitchen and bath redesigns, wall removals, and structural updates. We draw the plans — you hire the contractor.
New rooms, bedroom additions, second stories, and square footage expansions — fully permitted and code-compliant.
Ground-up home builds and whole-home designs. Full plan set from concept to permit approval.
zHeight — Mountain View
We handle the complete permit package — architectural drawings, structural engineering, separate utility connection plans with in-house Title 24 CF1R included, ePermitsMV submission, and correction response. No planning permit needed in Mountain View — just a building permit.
All regulatory data verified 2026-08-18 against City of Mountain View, Mountain View Zoning Code Chapter 36, ePermitsMV, CA HCD, and CA Gov. Code §66310–66342. Fee amounts should be confirmed with Building Division at (650) 903-6313 before budgeting.