Permit guides

ADU Permits in Martinez: a Homeowner's Guide

Martinez gives away pre-approved ADU plans with reduced fees — and now allows up to four ADUs on a single-family lot.

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

Who handles your permit

ADU permits in Martinez run through the Community Development Department, Planning Division. The city's standout offering is its Pre-Approved ADU Plans Program: free downloadable plans with expedited review and reduced permit and plan-check fees. In September 2026 the council also adopted an urgency ordinance aligning local rules with state guidance — including up to four ADUs on a single-family lot.

What you can build

Martinez's headline numbers:

FREEPre-approved ADU plans, downloadable

ReducedPermit and plan-check fees on pre-approved plans

Up to 4ADUs allowed on a single-family lot (2026 ordinance)

1,200 sq ftMax for a detached ADU

16 ftHeight limit for most detached ADUs

4 ftMinimum rear and side setbacks

The four-unit allowance combines a local ADU, a state ADU, a JADU, and a detached state ADU per recent HCD interpretation adopted by the council.

Free plans, reduced fees — with conditions

The Pre-Approved ADU Plans Program covers the architectural plans, structural plans, and Title 24 energy forms — you handle the site plan, grading plan, contractor, materials, permit application, outside agency approvals, and inspections. Solar PV, utilities, and fire sprinklers (if required) go in as deferred submittals.

The catch: if you modify the plans, you lose the expedited review and reduced fees and fall back to standard plan check. Site-specific conditions that the stock plans can't meet mean hiring a design professional.

Use them unmodified or go custom. The fee and time savings only survive if the pre-approved plans stay exactly as drawn.

What goes into the submittal

For the pre-approved track:

Download and select the free pre-approved plan
ADU Checklist and Building Permit Application
Site plan and grading plan (homeowner's responsibility)
Deferred submittals: solar PV, utilities, fire sprinklers if required
Outside agency approvals as applicable

Where applications usually get stuck

Modified plans. Any modification voids expedited review and reduced fees.
Site fit. Slopes, easements, or odd lots can make stock plans unworkable — get a professional opinion first.
Outside agencies. Their approvals aren't covered by the program and run separately.
Four-unit complexity. The new allowance is powerful but each unit still needs its own compliant design.

Not sure where to start? That's the part we do. We look at your property, map the requirements, coordinate the plans and specialists, and manage the submittal 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