Governor Newsom signed the 2026 housing bills on September 27 and 29, 2026. Seven of them change what a California homeowner can build, what a city can charge, or how long a permit can be held up. All seven are ordinary, non-urgency statutes, so they take effect on January 1, 2027. This page summarises each one from the chaptered bill text on the Legislature's website, says who it helps, and flags what it does not do.
Two of the seven bills amend the ADU statute itself. Two speed up building-permit review for housing generally. Two are about factory-built homes, which is how most prefab ADUs are regulated. One concerns electrical service connections. None of them changes the size, height or setback guarantees that homeowners already rely on.
| Bill | What changes on January 1, 2027 | Who it matters to |
|---|---|---|
| AB 956 Quirk-Silva · Ch. 791 | Cities must approve two detached, new-construction ADUs on a lot with a single-family home, up from one. | Owners with room for a second backyard unit |
| SB 1117 Cervantes · Ch. 809 | On an ADU larger than 750 sq ft, impact fees apply only to the area above 750 sq ft, for the first two ADUs on a lot. | Anyone building larger than 750 sq ft |
| AB 1621 Wilson · Ch. 780 | No more than two plan-check rounds on a building permit application; faster appeal deadlines. | Anyone stuck in repeated corrections |
| SB 1014 Grayson · Ch. 806 | On request, an estimate of required improvements within 30 business days, and an itemised list once a permit application is complete. | Projects facing surprise street, sewer or utility work |
| AB 1815 Wicks · Ch. 782 | Cities cannot apply local building standards to factory-built housing that exceed or differ from the state code. | Prefab and modular ADU buyers |
| AB 2058 Harabedian · Ch. 783 | Local inspection and permitting fees for factory-built housing are capped at 50% of the site-built equivalent unless the city documents its costs. | Prefab and modular ADU buyers |
| SB 1196 McNerney · Ch. 684 | The Public Utilities Commission must set timelines for small electrical service connections by September 30, 2027. | Anyone waiting on a utility to energise a finished unit |
Until now, the by-right list in Government Code section 66323 guaranteed one detached, new-construction ADU on a lot with a single-family home. AB 956 changes "one" to "two". From January 1, 2027 a city or county must approve, ministerially and without a hearing, two detached, new-construction ADUs that keep four-foot side and rear setbacks on a lot with a proposed or existing single-family dwelling. The same section separately covers an ADU or junior ADU created within existing space; that part is unchanged.
Two limits stay in the text. A city may cap each detached unit at 800 square feet of livable space and apply the state height limits. And a city is not required to also approve a junior ADU on a lot where two detached ADUs have been built under this provision.
AB 956 also widens the rule that voids HOA covenants and deed restrictions which block ADUs. Civil Code sections 714.3 and 4751 used to protect lots "zoned for single-family residential use". They now protect lots "zoned to allow single-family residential use", which reaches lots in zones that permit houses alongside other uses.
What it does not do: it does not raise the 800 square foot guarantee or change setbacks, and it does not stop a city from allowing more. Under Government Code section 66316, a local ADU ordinance that does not meet the state requirements is void and the city must apply the state standards until it adopts a compliant one, so the two-unit rule does not depend on your city amending its own text. Planning counters may still take time to catch up; ask how yours is handling applications around January 1.
The full text, the limits and what to ask your city: AB 956 in detail.
Impact fees are the one-off charges for parks, roads, and other infrastructure. Existing law already bars any impact fee on an ADU of 750 square feet or less. The catch was the cliff: at 751 square feet the whole unit became chargeable, in proportion to the size of the main house. Adding one square foot could add thousands of dollars in fees.
SB 1117 removes the cliff. Under amended Government Code section 66311.5, for up to two ADUs on a lot, impact fees on an ADU larger than 750 square feet are still charged proportionately to the primary dwelling, but "only on the area in excess of 750 square feet of interior livable space". A 1,000 square foot ADU is charged on the 250 square feet above the threshold rather than on all 1,000.
Three limits. The rule covers the first two ADUs on a lot; a lot with more than two keeps the old whole-unit method. "Impact fee" does not include utility connection fees or capacity charges, which have their own rules in the same section. And agencies will each have to work out how they apply the proportional formula to the excess area, so ask for the fee calculation in writing before you size the unit.
The full text, the limits and what to ask your city: SB 1117 in detail.
Plan check is where projects stall. The building department returns corrections, the designer resubmits, and new comments appear on the third and fourth round. AB 1621 amends Government Code section 65913.3 so that a local or state agency "shall not require or request more than two plan check and specification reviews in connection with an application for a building permit". After two rounds the agency may deny an application that still does not comply; further resubmittals happen at the applicant's request, not the agency's.
The bill also restricts an agency from using a site inspection to demand a change that departs from plans it has already approved, subject to exceptions in the statute. And it shortens the deadline for deciding an appeal of an "incomplete" or "non-compliant" finding to 30 business days for projects of 25 units or fewer.
Does it cover a single ADU? The statute is written for "postentitlement phase permits", defined to include building permits for development that is at least two-thirds residential, and its deadlines are framed around housing development projects. A stand-alone ADU building permit appears to fit that language, and ADUs keep their own 60-day decision deadline under the ADU statute either way. Because the bill does not mention ADUs by name, ask your building department in writing how it will apply the two-review limit to your application.
The full text, the limits and what to ask your city: AB 1621 in detail.
SB 1014 adds Government Code section 65941.3. An applicant for a housing development project can ask for a preliminary estimate of the improvements a city or county will require, such as street, sidewalk, sewer, water or utility work, and the agency must provide it within 30 business days. Separately, within 30 business days of deeming a post-entitlement permit application complete, the agency must give the applicant an itemised list of every on-site and off-site improvement it will require in connection with that permit.
Like AB 1621, the bill is drafted around housing development projects rather than ADUs specifically, so confirm with your city whether it treats an ADU application as covered. Where it applies, it targets one of the most common budget shocks in an ADU project: off-site work that nobody priced at the start.
Factory-built housing is approved by the state at the factory. The local building department's role is the foundation, the utility connections and the installation. AB 1815 adds Health and Safety Code section 19993.1: a city, county or district "shall not impose or enforce local building standards applicable to a factory-built housing structure" that exceed or differ from the applicable mandatory standards in the California Building Standards Code, and may not enforce local energy-efficiency or green-building amendments on those structures that exceed the state's mandatory minimums. Changes justified by local climate, geology or topography remain possible if the city makes the required findings.
AB 2058 goes after cost and scheduling. A local agency's fee for inspecting the installation of factory-built housing, and its permitting fee for a factory-built housing structure, may not exceed 50 percent of the equivalent fee for site-built housing unless the agency adopts written findings with substantial evidence of its actual costs. Once the Department of Housing and Community Development adopts regulations, which the bill requires by January 1, 2029, a buyer can choose to have a state-approved quality assurance agency carry out the installation inspection, at the buyer's cost.
For a homeowner comparing a prefab unit with a site-built ADU, the practical effect is fewer city-specific surprises after the unit leaves the factory and lower local fees on the factory-built portion. Site work, foundations and utility trenching are untouched by either bill, and they remain a substantial part of what a prefab project costs.
A finished ADU that cannot get its electrical service energised cannot be occupied. SB 1196 amends the Powering Up Californians Act to require the Public Utilities Commission to set, by September 30, 2027, timelines for electrical corporations to respond to and process "small energization projects": connections that need no distribution or service line extension, or only a new meter.
Read it narrowly. The bill does not mention ADUs. Nothing changes on January 1: enforceable timelines arrive only when the Commission adopts them. And it is addressed to electrical corporations, the investor-owned utilities the Commission regulates. Publicly owned utilities such as LADWP and SMUD are a separate category under the Public Utilities Code and are not covered by these timelines.
Whether any of this affects your project depends on its timing and on your city. Four questions are worth asking.
For how long the build itself takes once the permit is issued, see our measured build times for California cities.
Every statement above was checked on October 5, 2026 against the bill's status and chaptered text on the California Legislature's website (leginfo.legislature.ca.gov). Each bill shows "Chaptered by Secretary of State" with the chapter number given in the table, and each is recorded as a non-urgency measure. Under the California Constitution a non-urgency statute enacted in the regular session takes effect on January 1 of the following year.
This is a plain-English summary for homeowners, not legal advice, and it does not cover every housing bill signed this year. Where a bill is drafted for housing development generally rather than for ADUs, we have said so instead of guessing how each city will apply it. If your project turns on one of these provisions, read the section itself and confirm with your planning or building department.
January 1, 2027. All seven bills were signed on September 27 or 29, 2026 as non-urgency statutes. Two pieces arrive later: the utility connection timelines under SB 1196 depend on the Public Utilities Commission, which has until September 30, 2027 to set them, and the third-party installation inspections under AB 2058 wait on state regulations due by January 1, 2029.
Generally yes, if the units meet the conditions in the statute. From January 1, 2027, AB 956 requires cities and counties to ministerially approve two detached, new-construction ADUs with four-foot side and rear setbacks on a lot with a single-family home, up from one. A city may cap each at 800 square feet of livable space and apply the state height limits, and it is not required to also approve a junior ADU on a lot where two detached ADUs have been built this way.
From January 1, 2027, only on the area above 750 square feet. Under SB 1117 this applies to the first two ADUs on a lot; the fee is still proportionate to the size of the main house. ADUs of 750 square feet or less remain exempt from impact fees. Utility connection fees and capacity charges are separate and are not covered by this rule.
Two, for a building permit application covered by Government Code section 65913.3 as amended by AB 1621. After that the agency may deny a non-compliant application, and further resubmittals happen only at the applicant's request. The statute is written for residential building permits generally and does not name ADUs, so confirm in writing how your building department applies it.
No. The 800 square foot guarantee, the four-foot side and rear setbacks and the state height limits are unchanged. The 2027 bills change how many detached units a single-family lot can have, how impact fees are calculated above 750 square feet, and how permits and factory-built units are processed.
Yes, in two ways. AB 1815 stops cities from applying local building standards to factory-built housing that exceed or differ from the state building code. AB 2058 caps local inspection and permitting fees for factory-built housing at 50 percent of the site-built equivalent unless the city documents its actual costs. Neither bill changes the cost of site work, foundations or utility connections.