Short answer: If you want the lowest entry and the best cash flow, Westminster wins. If you want the biggest lots and a 1,200 sq ft ADU with county pre-approved plans, Midway City wins. It’s an unincorporated pocket with 8,000+ sq ft lots near $1.1 million. If you want top schools and the strongest resale, Fountain Valley wins, but it costs about $175,000 more, caps a 2-bed ADU at 1,000 sq ft and needs closer to 50% down to cash flow.
These three areas touch each other in west Orange County, between Garden Grove, Huntington Beach and Costa Mesa. Midway City sits inside Westminster on the map, but it isn’t part of the city. The County of Orange approves its permits. That one detail changes the rules more than most buyers expect. Below is how the three compare on price, lots, ADU rules, rents and the monthly payment.
Last updated: October 2026. Dylan Serna, The ADU Realtor.
Fountain Valley vs. Midway City vs. Westminster at a Glance
| Fountain Valley | Midway City | Westminster | |
|---|---|---|---|
| Who approves the ADU | City of Fountain Valley | County of Orange (unincorporated) | City of Westminster |
| Typical value, all homes (Zillow) | About $1,377,000 (Sept. 2026) | Few sales; houses listed $1.05M to $1.4M | About $1,093,000 (Sept. 2026) |
| Realistic price, 3-bed house with ADU room | About $1,250,000 | About $1,100,000 | About $1,075,000 |
| Typical lot | 6,000 to 7,500 sq ft | About 8,100 sq ft on many streets | 6,000 to 7,500 sq ft; RV-access corners in 92683 |
| Max detached ADU | 850 sq ft (studio/1 bed), 1,000 sq ft (2+ bed) | 1,200 sq ft | 1,200 sq ft |
| Separation from house | 10 ft, rear yard only | State baseline | 6 ft |
| New 2-bed ADU rent | About $3,000 | About $2,900 | About $2,800 to $3,000 |
| Rule that trips up buyers | Design and entry rules; an outdated owner-occupancy line | County permit counter, not city hall | Unit-count wording in the city code |
Sources: Fountain Valley ADU rules (FVMC 21.08.055), the city’s ADU standards handout, Westminster Municipal Code 17.400.135, OC Development Services ADU page, Zillow, Rentometer and CRMLS. Rules change, so confirm any parcel with the agency that permits it before you write an offer.
What It Costs to Get In
- Westminster is the cheapest of the three. Zillow’s typical value is about $1,093,000, up 5.5% in a year, and homes go pending in about 19 days. The best ADU lots I see are 7,000 sq ft RV-access corners in 92683 near the Huntington Beach line, which I priced out in Westminster RV corner lots: the ADU numbers. This fall, overpriced Westminster homes took big cuts, so there’s room to negotiate.
- Midway City is tiny, so sales are rare and the medians bounce around. What matters is the lots. Recent single-family listings sat on 8,100 sq ft parcels: 14772 Jefferson St asked $1,050,000 for a 2-bed, and 14641 Harper St asked $1,399,200 for a 3-bed. That’s 1,000 to 2,000 sq ft more dirt than most Westminster and Fountain Valley tracts.
- Fountain Valley is the priciest. Zillow’s typical value is about $1,377,000, up 6% in a year, and homes go pending in 13 days. You’re paying for the schools (Fountain Valley High and Los Amigos), a planned-city layout and low crime. A 3-bed house with room for a backyard unit runs about $1,200,000 to $1,300,000.
ADU Rules Compared
All three follow state ADU law: 4-foot side and rear setbacks, a 60-day ministerial approval, no impact fees at 750 sq ft or less and a 30-day minimum rental. The state baseline is on California HCD’s ADU page. The differences are size, placement and who you’re dealing with.
Fountain Valley: smaller cap, more design rules
Fountain Valley caps a detached ADU at 850 sq ft for a studio or 1-bed and 1,000 sq ft for 2+ bedrooms. That fits a 2-bed, 2-bath but not a full 3-bed. The city handout adds rules the other two don’t have:
- Rear yard and 10 feet. A detached ADU goes in the rear yard, at least 10 feet from the house.
- Matching design and hidden entries. The ADU has to match the house’s materials and roof, and its entrance can’t face the street.
- Two stale requirements. The handout says ADUs built after 2025 must be owner-occupied, and the code requires a recorded covenant. State law bars owner-occupancy for an ADU (Government Code 66315), and in December 2024 HCD told the city the covenant has to go. Get Planning’s answer in writing before you close.
Midway City: county rules and pre-approved plans
Because Midway City is unincorporated, your ADU goes through OC Development Services under County Zoning Code 7-9-90, not Westminster City Hall. Three things I like about that:
- 1,200 sq ft detached. On an 8,100 sq ft lot, that’s a real 3-bed, 2-bath.
- Three units on one lot. The county allows one conversion ADU, one JADU and one new detached ADU, applied for online through myOCeServices.
- Pre-approved ADU plans. The county offers standard plans that skip most of the design cost and plan-check back-and-forth.
One heads-up: Midway City mailing addresses sometimes read “Westminster.” Pull the parcel on the county assessor map to confirm which agency permits it.
Westminster: 1,200 sq ft and a short separation
Westminster allows a detached ADU up to 1,200 sq ft with only 6 feet of separation from the house, the shortest of the three. That’s why RV-access lots work so well here. Two things to check: the city code’s wording on combining an ADU and a JADU is narrower than state law, and the City Engineer can restrict ADUs where sewer or water is limited. I cover both in Garden Grove vs. Westminster vs. Santa Ana.
What changes in 2027
Starting January 1, 2027, AB 956 lets many single-family lots add two detached ADUs. That’s where Midway City’s 8,100 sq ft lots pull ahead. A second detached unit is much easier to fit on 8,100 sq ft than on 6,000.
What ADUs Rent For
| Unit | Fountain Valley | Midway City | Westminster |
|---|---|---|---|
| 1 bed ADU | About $2,300 | About $2,100 | About $2,100 |
| 2 bed ADU, newer | About $3,000 | About $2,900 | $2,800 to $3,000 |
| 3 bed ADU, 1,100+ sq ft | Doesn’t fit the 1,000 sq ft cap | About $3,400 | About $3,400 |
| Main house, 3 bed | About $4,400 | About $4,200 | $4,200 to $4,400 |
Fountain Valley figures are based on Rentometer’s October 2026 averages ($2,315 for 1-bed, $2,994 for 2-bed, $4,443 for 3-bed). Westminster figures come from my lease comps in what a Westminster ADU can rent for. Midway City has too few rentals for its own data, so I use Westminster comps.
The Payment Math: Buy a House, Build a 2-Bedroom ADU
I keep this simple: total monthly payment (principal, interest, taxes and insurance) against total rent. Same plan everywhere: buy a 3-bed house, pay cash for a 1,000 sq ft, 2-bed detached ADU at about $330,000 all-in, then rent both. 1,000 sq ft fits all three caps.
Assumptions: 7.75% on a 30-year investment loan (Freddie Mac’s weekly survey had the owner-occupied rate at 7.32% on October 22, and investor loans price higher), property tax at 1.15% of price plus build cost, and $200 a month for insurance.
| Fountain Valley | Midway City | Westminster | |
|---|---|---|---|
| Purchase price | $1,250,000 | $1,100,000 | $1,075,000 |
| Main house rent + ADU rent | $4,400 + $3,000 = $7,400 | $4,200 + $2,900 = $7,100 | $4,200 + $2,900 = $7,100 |
| 25% down: cash in (down + build) | $642,500 | $605,000 | $598,750 |
| Monthly PITI | About $8,430 | About $7,480 | About $7,320 |
| Rent minus PITI | About -$1,030 | About -$380 | About -$220 |
| 50% down: cash in (down + build) | $955,000 | $880,000 | $867,500 |
| Monthly PITI | About $6,190 | About $5,510 | About $5,400 |
| Rent minus PITI | About +$1,210 | About +$1,590 | About +$1,700 |
Before vacancy, repairs and management. Set aside 5% to 10% of rent for those.
How I read this table:
- None of the three cash flow at 25% down. That’s normal in Orange County. Westminster comes closest, about $220 a month short.
- Midway City’s real edge is the second unit. On the same plan it trails Westminster by about $160 a month. Build a 1,200 sq ft 3-bed instead and rent rises about $500. Add a second detached ADU in 2027 and no Fountain Valley lot can match it.
- Fountain Valley is a 50%-down hold. It’s about $1,000 a month short at 25% down. You buy it for schools, tenant quality and resale. A break-even property in a neighborhood like this can still be a good hold.
Which One Fits Your Plan?
Choose Westminster if…
- You want the lowest price and the best cash flow of the three.
- You can find an RV-access or corner lot with a clear path to the back.
- You want room for a 1,200 sq ft, 3-bed unit.
Choose Midway City if…
- Lot size is your priority, especially for two detached ADUs in 2027.
- You’d like to use county pre-approved plans.
- You’re patient. Only a handful of houses sell each year.
Choose Fountain Valley if…
- You can put about 50% down and plan a long hold.
- Schools and resale matter more than first-year cash flow.
- A 1,000 sq ft, 2-bed ADU is enough for your plan.
Comparing more of west and coastal OC? See Huntington Beach vs. Costa Mesa vs. Irvine, or browse my Garden Grove and Costa Mesa ADU homes pages next door.
Frequently Asked Questions
Is Midway City part of Westminster?
No. Midway City is an unincorporated community surrounded by Westminster. The County of Orange, not the city, approves ADU permits there.
How big can an ADU be in Fountain Valley?
850 sq ft for a studio or 1-bed and 1,000 sq ft for 2+ bedrooms, detached, in the rear yard and at least 10 feet from the house.
How big can an ADU be in Westminster and Midway City?
Up to 1,200 sq ft detached in both. Westminster requires 6 feet of separation from the house.
Which is cheapest for an ADU investment?
Westminster. A 3-bed house with ADU room runs about $1,075,000, compared with about $1,100,000 in Midway City and $1,250,000 in Fountain Valley.
Do I have to live on the property to build an ADU in Fountain Valley?
State law says no for an ADU; owner-occupancy can apply only to a JADU. The city’s handout still lists an owner-occupancy line, so confirm with Planning in writing.
Find the Right Lot in West OC
Midway City lots rarely hit the market, and the good Westminster corners go fast. Tell me your budget and goal, and I’ll watch all three areas for lots that fit, with ADU size, rent and build cost for each one. You can also browse ADU homes for sale now.
👉 Book a buyer ADU consult call to go through your options with Dylan
Prefer to talk now? Call Dylan Serna, ADU Realtor at 714-860-2868.
Dylan Serna | The ADU Realtor | eXp Realty | DRE #02217359
This post is general information, not legal, tax or financial advice. Prices, rents and payments are estimates based on 2026 Zillow, Rentometer, Redfin and CRMLS data. Confirm ADU rules for any specific property with the City of Fountain Valley, the City of Westminster or OC Development Services.
