Second Dwellings on AE‑20: Investor Playbook

Looking at AE-20 land in the Burrell district and wondering if you can add a second home for income or family use? You are not alone. Investors love the big acreage and price points, but the rules and rural infrastructure can be tricky. In this guide, you will learn the difference between an ADU and a second principal residence, what permits you need, the site checks that make or break a project, and a step-by-step playbook to underwrite your deal with confidence. Let’s dive in.

AE-20 basics and your two paths

AE-20 means Exclusive Agricultural with a 20-acre minimum lot size. It prioritizes farming while allowing limited residential uses. Always start by reviewing Fresno County’s current zoning rules for AE-20 to confirm what is allowed on your parcel in Burrell or Riverdale. You can access the county’s zoning ordinance portal for the latest language and updates. Review Fresno County’s Zoning Ordinance.

There are two very different ways to add a second dwelling:

• Accessory Dwelling Unit, or ADU. This is a secondary unit on the same lot as a primary home. ADUs are covered by state ADU law and are reviewed ministerially under set timelines and standards. Start with the state’s ADU Handbook for rules, timelines, and fee limits. See HCD’s ADU guidance.
• Second principal residence. On AE-20, this often requires a discretionary county approval such as a Director Review or Conditional Use Permit. Recent county cases show conditions like owner occupancy or size caps. Review current examples to understand common conditions. Check Fresno County Project Review notices.

One crucial difference affects investors. State law permanently removed owner-occupancy requirements for ADUs, which expands rental flexibility. That change does not automatically apply to second principal residences approved through county discretion. Read the AB 976 text.

Permitting routes in unincorporated Fresno County

ADU permitting at a glance

Fresno County offers ADU guidance and preapproved plan sets, which can shorten review time. State law sets a 60-day ministerial review for ADUs, and using a preapproved plan can reduce that timeline further once implemented locally. For local intake, submittal standards, and low water area notes, start here: Fresno County ADU resource page.

State rules also limit impact fees for ADUs. Units under 750 square feet are generally exempt from local impact fees, and larger ADUs must be charged proportionately. The HCD ADU Handbook summarizes timelines and fees in one place. Review HCD’s ADU standards.

Second principal residence approvals

A second principal residence on AE-20 typically requires a Director Review or CUP, public notice, and environmental review. Expect longer timelines and case-specific conditions that can include owner occupancy, size caps, or use limits. Review recent county postings to see current approval patterns. See Fresno County Project Review examples.

Site and infrastructure checks that make or break it

Water supply and SGMA

Water is the first gate in the Burrell and Riverdale area. Many AE-20 parcels rely on private wells and may fall under SGMA rules. Fresno County regulates well permits and notes that ADUs are not allowed in some low water areas. Before you buy, confirm well capacity, depth, and GSA constraints. Start with the county’s Well Permitting Program and the Fresno County ADU page for low water notes.

Septic feasibility

If you do not have public sewer, you will likely need a new or expanded septic system. That means perc testing, setbacks, and space for a new leach field. If the soils or lot configuration do not support a second system, your project may not pencil. Check Environmental Health’s septic guidance.

Utilities and access

Rural service runs add cost. Allow for panel upgrades, trenching, and a potential new transformer for a detached unit. Broadband availability can influence rental demand. Fire access standards, driveway width, turnouts, and water supply can also add line items, so engage the fire authority early.

Williamson Act and special designations

Many agricultural parcels in Fresno County are under Williamson Act contracts that lower taxes but restrict nonagricultural development. If your parcel is under contract, you may need compatibility findings or other steps before adding a residence. Review the Williamson Act program. Also check county GIS and FEMA maps for floodplains or habitat that could add cost or delay. Use the zoning ordinance portal for references.

Cost, rent, and return modeling in Riverdale

ADU costs vary by type and site. Central Valley ranges often run from about $150 to $350 per square foot for new detached ADUs, with prefab options sometimes lowering schedule and certain costs. Garage conversions can be less. Always get multiple contractor bids. See a cost overview for ADUs.

Rents in Riverdale are modest compared with big metro areas and data can be thin in small towns. Your cash flow hinges on realistic rent comps, vacancy assumptions, and build costs. Model conservatively, and remember new construction creates a supplemental property tax assessment. For financing, check whether a CalHFA ADU Grant or an ADU loan product is available, especially if you will occupy the property. Explore CalHFA’s ADU programs.

Step-by-step investor playbook

1. Confirm zoning and overlays

• Verify the parcel is AE-20 and read the current code language. Ask planning about any special overlays that affect second dwellings. Check the zoning ordinance.

2. Choose your path: ADU or second residence

• If your plan is a rental unit, aim for an ADU if setbacks, water, and septic allow it. It is faster and more predictable. See Fresno County’s ADU page and HCD’s ADU guidance for standards and timelines.

3. Run water and septic feasibility first

• Pull the well log, confirm yield, and ask which GSA covers the parcel. Order a perc test and septic design review. If either fails, the deal likely does not work. Well Permitting Program and Septic guidance.

4. Price out utilities and site work

• Get service letters and estimates for electrical, gas if applicable, and internet. Budget driveway, grading, foundation, and fire-access improvements. Secure at least two build bids or a prefab quote. ADU cost overview.

5. Check Williamson Act status

• Confirm whether the parcel is under a Williamson Act contract and how that affects adding a residence. Williamson Act program.

6. Validate fees, taxes, and timelines

• For ADUs under 750 square feet, impact fees are typically exempt. Larger ADUs pay proportionate fees. Confirm county processing timelines and plan on a supplemental assessment after completion. HCD’s ADU standards.

7. If discretionary, learn the conditions

• For second principal residences, review recent AE-20 approvals to see common conditions such as owner occupancy or size limits. Fresno County Project Review notices and AB 976 to understand how ADUs differ on occupancy rules.

8. Line up financing

• If eligible, see whether CalHFA’s ADU Grant or lender products are available. Otherwise, compare HELOC, cash-out refi, and construction loan options for rural builds. CalHFA ADU programs.

When you want a second income stream on AE-20 land, a clean feasibility path beats a hopeful pro forma. If the ADU route fits your site and water and septic check out, you can often reach permits in 30 to 60 days using preapproved plans. If the site needs a second principal residence, expect a longer runway and plan for conditions.

Ready to pressure-test a specific parcel or map the best path to a second dwelling in Burrell or Riverdale? Tap a Central Valley advisor who blends transaction know-how with build and permitting insight. Connect with Ruben Olguin to review your options and build a clear, step-by-step plan.

FAQs

Can you add a rental ADU on any AE-20 parcel in Burrell?

• Not always. ADUs are allowed under state law in many cases, but local low water restrictions, well yield, septic feasibility, and land conservation status can block an ADU. Start with county ADU guidance and confirm water and septic first.

What is the difference between an ADU and a second principal residence?

• An ADU is accessory to an existing home and receives ministerial review under state law. A second principal residence is a separate home that typically needs a Director Review or CUP with public notice and possible conditions.

Are owner-occupancy rules required for new ADUs?

• No. State law removed owner-occupancy requirements for ADUs, but the county can still impose conditions on second principal residences approved through discretionary permits.

What site issues most often derail second dwellings in Riverdale?

• Well capacity and septic feasibility are the top deal breakers, followed by long utility runs, fire-access standards, and Williamson Act restrictions.

How long does permitting take for a second unit on AE-20?

• A ministerial ADU can often be permitted in 30 to 60 days when using preapproved plans. A second principal residence typically takes several months or more due to environmental review and hearings.