Selling a Duplex or Small Apartment Building in Alameda County

A duplex, triplex or small apartment building sells differently from a single-family home. Who can buy it depends on how many units it has, and its price depends heavily on the rents already in place. In Oakland and Berkeley, larger wood-frame buildings also come with seismic retrofit rules. This guide is for Alameda County owners of small multi-unit properties who are thinking about selling, whether they live in one of the units or not.

Two to four units vs. five or more

Lenders draw a hard line at four units, and it shapes who can buy your property.

Two to four units count as residential. Buyers can use the same kinds of mortgages they’d use for a house, including FHA loans if they’ll live in one of the units. Fannie Mae allows as little as 5% down on some 2–4 unit purchases when the buyer will live there (larger high-balance loans need more), and part of the rent from the other units can help the buyer qualify. For three- and four-unit properties, FHA also requires the property’s projected rents, minus an allowance for vacancy and maintenance, to cover the full mortgage payment.
Five or more units are multifamily properties. Loans for them are underwritten mainly on the building’s own income: the lender compares its net cash flow with the loan payments.

A 2–4 unit property can draw owner-occupants, who are buying a home plus rental income, as well as investors. A building with five or more units sells almost entirely to investors, who price it on what it earns.

An owner-occupant buyer needs an empty unit

A buyer who plans to live in the property needs a unit to live in. That means a unit that’s vacant at closing, or ending a tenancy after the purchase for owner move-in, which brings just-cause rules, notice periods and relocation payments. A vacant unit when you list can widen the pool of buyers for a duplex or triplex. If every unit is occupied, expect most of your interest to come from investors.

If you live in one half of a duplex, it may be exempt from the statewide rent cap and just-cause rules (AB 1482), but only while you keep living there. The exemption applies to tenancies that began while you lived in the other unit, so it won’t carry over to a buyer.

How rent control shapes the price

Investors start with the rents in place. Long-term tenants paying well below market mean less income and a lower price, even for a building in good condition.

In Alameda County, rent limits come from several layers. AB 1482 caps increases on most units more than 15 years old at 5% plus inflation, never more than 10% a year. Oakland, Berkeley, Alameda and Hayward add tighter caps on many older apartment buildings, and in Oakland, increases an owner banked but never took generally can’t pass to a buyer. San Leandro’s new limits on most apartments built by February 1, 1995 start January 1, 2027, and rents above the July 1, 2025 level plus the allowed increase will have to come down. The state Costa-Hawkins Act limits how far those local rules reach: units with a certificate of occupancy issued after February 1, 1995, and separately sellable single-family homes and condos, are exempt from local rent caps, and owners can generally set a new rent when a unit turns over, with some exceptions.

So a building is priced on today’s rents, with some value for the chance to raise them as units turn over. Recent turnover, accurate registrations with the city and clean records of past increases all help a buyer trust the numbers.

The paperwork buyers will ask for

Gather these before you list or ask for offers:

a rent roll showing each unit’s tenant, move-in date, current rent, deposit and last increase
copies of every lease, amendment and side agreement
tenant estoppel certificates, in which each tenant confirms their rent, deposit and terms
records from the city’s rent program, such as registrations and past rent increase notices
12 months of income and expenses, plus utility, insurance and property tax bills
permits, any notices of violation and the building’s soft-story status, if it applies

Deposits move with the sale. California requires you to transfer each one to the buyer, with written notice to the tenant, or return it to the tenant. Our guide to selling a rental property walks through deposits, showings and the tax side.

Soft-story retrofit rules in Oakland and Berkeley

Both cities require seismic retrofits of certain wood-frame apartment buildings with five or more units and a weak ground floor, often one with tuck-under parking or open storefronts.

Oakland covers buildings built or permitted before January 1, 1991. All of the ordinance’s base deadlines have passed, the last in February 2025, though the city can grant one-year extensions. The ordinance says a sale doesn’t change any deadline. The city publishes a list of potential subject buildings with their compliance status and reports each building’s status to the County Clerk-Recorder every six months.
Berkeley covers buildings whose original building permit was applied for before January 1, 1978. Most buildings on its list have already been retrofitted. If an unretrofitted building is sold, the owner must apply for a retrofit permit within six months and finish within 18 months of applying. Berkeley also records a certificate with the County Recorder for each covered building and requires tenant notices and an earthquake warning sign until the building comes off the list.

Buyers and lenders can look these lists up. An unfinished retrofit doesn’t stop a sale, but expect it to be priced in.

Taxes in brief

If you live in one unit of a duplex, the IRS treats your unit as your home and the other as a rental. Gain on your unit may qualify for the home-sale exclusion, while gain on the rental side generally doesn’t unless you lived in that part too. Depreciation on the rental portion is taxed when you sell, and a 1031 exchange can defer tax on investment property. A tax professional can split the numbers before you sign.

Selling as-is, with tenants in place

If you’d rather not empty units, chase estoppels or finish a retrofit before selling, a direct sale is an option. EZ Home Offer buys across Alameda County as-is, and we can buy with tenants in place. We usually make a written cash offer within 24 hours, charge no fees or commissions, cover typical closing costs and can close in as little as 3 days once title is clear. Our offer will be below what a fully leased, updated building might bring, which is the trade for skipping the work. See our page on selling a rental with tenants, or our Oakland page if your building is there.

Sources

General information about California rules as of October 3, 2026, not legal, tax or financial advice. Laws change and every situation is different, so check the details with an attorney, CPA or other professional.