Permit guides

ADU Permits in Vacaville: a Homeowner's Guide

Pre-reviewed detached ADU plans, published review times, and the e-TRAKiT portal — how the Vacaville process works, in plain language.

Last updated October 2026. Rules change; always confirm current requirements with the city before you build.

Who handles your permit

In Vacaville, ADU permits go through the Building Division at 650 Merchant Street, with submittals via the city's e-TRAKiT portal. Vacaville publishes its service standards: a minimum of 15 business days for the first plan review, five business days for subsequent reviews, and a 60-day decision standard for complete ADU applications.

What you can build

1,200 sq ftMax for a detached ADU under state law

16 ftHeight limit for most detached ADUs

4 ftMinimum side and rear setbacks, detached ADUs

15 daysMinimum first plan review — subsequent rounds take 5

60 daysDecision standard for a complete ADU application

1 + 1One ADU plus one Junior ADU per single-family lot

Vacaville's pre-reviewed ADU plans

The city offers pre-reviewed detached ADU plans in four sizes — 375, 550, 743, and 908 sq ft — that shorten the review path for homeowners willing to use a stock design. Note the top size sits just under the 750 sq ft fee-exemption line, and the bottom two keep impact fees at zero.

The school fee form is a gate. Vacaville requires a school development fee form completed before permit issuance — the district and the city don't always move at the same speed, so get this paperwork started early rather than waiting for plan check to finish.

What goes into the submittal

Building permit application via e-TRAKiT
Site plan: lot lines, structures, setbacks, easements, utilities, drainage
Architectural plans: floor plans, elevations, sections
Structural plans and calculations, Title 24 energy documents
School development fee form (required before issuance)

Where applications usually get stuck

School fee paperwork. The form required before issuance is the classic last-week surprise.
Garage conversions and parking. Vacaville has specific garage-conversion parking rules — converting the garage without resolving replacement parking stalls the permit.
Corrections cycles. The 15-business-day first review is a minimum; each correction round adds five more, so complete first submittals matter.
Under-750 design drift. Creeping past 750 sq ft during design adds impact fees that the pre-reviewed sizes were designed to avoid.

Not sure where to start? That's the part we do. We check your property against Vacaville's requirements, compare the pre-reviewed and custom paths, and manage the submittal, school fee form, and corrections — one point of contact.

Tell us what you need help with.

Not sure where to start? That's what we're here for.

Send your project

Erik — (916) 540-8960 · Vall — (916) 956-8106
office@pcg-engineering.pro