Southern California Property Tools: Hazard Map, Mello-Roos Payment Calculator & What Sold Nearby

How to read the hazard layers

Southern California sells sunshine, but its buyers inherit floodplains, brush-covered canyons and active faults. California law already requires sellers to disclose many of these zones in the Natural Hazard Disclosure statement, usually late in escrow. This map lets you see them before you write an offer, next to the planned density for the same land.

Flood zones

Blue areas are high-risk flood zones, land with at least a 1% chance of flooding in any year. Zones beginning with A are riverine or shallow flooding; VE, in violet, is the coastal zone hit by waves; the floodway, in bright cyan, is the channel that must stay open to carry floodwater. Pale blue marks the 0.2% annual-chance (“500-year”) area, and tan is Zone D, where flood risk has not been studied. A home in a high-risk flood zone with a federally backed mortgage will usually need flood insurance. Tap the map to see the zone and, where one is listed, the base flood elevation.

Fire hazard severity zones

Yellow, orange and red show Moderate, High and Very High Fire Hazard Severity Zones from government hazard maps. The popup tells you whether the area is in a State Responsibility Area or a Local Responsibility Area. These zones bring stricter building standards for new construction, defensible-space rules around the house, and a disclosure duty when you sell. They can also affect whether an insurer will write a policy and what it costs, so get an insurance quote before you remove contingencies.

Earthquake fault zones

Magenta bands follow state-mapped active fault zones. The concern is ground rupture: a fault breaking the surface under a building. New buildings for people generally need a geologic investigation before a permit, and sellers must disclose the zone. Being outside a zone does not mean a home will not shake; every part of Southern California does.

Liquefaction and landslide zones (Seismic Hazard Zones)

Lime green marks liquefaction zones, where loose, wet soil can behave like a liquid in strong shaking. Brown marks earthquake-induced landslide zones on steeper ground. Both are “zones of required investigation”: a site study is needed before most new development, and sellers must disclose them. The state has mapped these zones mainly in the urban parts of Los Angeles, Orange and Ventura counties and in parts of western Riverside and San Bernardino counties. Large areas, including San Diego County, have not been evaluated, so a blank map there means “not mapped,” not “no hazard.”

Tsunami hazard areas

Light-blue areas with dashed outlines along the coast are the state’s tsunami hazard areas, used for evacuation planning. They help you know where to go in a warning; they are not insurance or building maps.

What to do next: If a home sits in or near a zone, ask for the Natural Hazard Disclosure report early, get an insurance quote on the address, ask about elevation certificates, defensible space or retrofit work, and confirm with the city, county, or other official office. Sea-level-rise projections are not on this map yet; a public coastal sea-level viewer covers the coast.

Schools on the map: what the layer shows, and what it cannot

Screening only

For many families the school question comes before the house. The map above shows about 4,600 open public campuses across Orange, Los Angeles, Riverside, San Bernardino and San Diego counties, along with school district boundaries. Tap a school for its grades, district, charter or magnet status, enrollment, the share of students who are socioeconomically disadvantaged or learning English, Title I status, and links to its public report card and school directory page.

The catch: assignment. A school near a home is not necessarily the school a child at that address would attend. Attendance boundaries are drawn by each district and change with enrollment, new campuses and closures. Attendance areas, where shown, are historical and may not match current assignments; we show that layer off by default, labeled as historical. Everywhere else the map shows school locations and district lines only, and we do not guess at assignments.

How to confirm. Ask the district. Los Angeles Unified’s Resident School Identifier and San Diego Unified’s School Finder look up the assigned schools for an address; most other districts post a school locator or will confirm by phone through their enrollment office. Seats, transfers, magnet and charter lotteries, and boundaries for new subdivisions are set by the district, so put any school contingency in writing before you remove it.

Not a rating. We do not score or rank schools, and we do not use paid rating services. For outcomes, read each school’s report on the state’s free California School Dashboard, and visit the campus.

Housing Element sites, ADUs and SB 9: what you can add, and what your city plans

Screening only, not a permit determination

Every California city and county must show the state that it has room for its share of new homes, its Regional Housing Needs Allocation. It does that in the housing element of its general plan, with a parcel-by-parcel inventory of sites zoned, or promised to be rezoned, for housing. Those inventories are public records. The map’s Housing Element sites layer, in teal, shows sites from public planning inventories, so you can see where your city expects apartments, townhomes or mixed-use buildings, and how many homes at which income levels it counted on each site.

What a site listing means. It means the city told the state the land can hold housing during the planning period, usually through 2029. It is not a permit, a project or a promise that anything will be built, and capacity numbers are planning estimates. If you are buying next to a listed site, read the city’s housing element and ask the planning department what is proposed. If you own a listed site, the listing alone does not give you new rights; the zoning does.

Coverage

Some cities and unincorporated areas are not shown on the map; those gaps are listed below. A missing city does not mean it has no housing sites, only that we do not have that inventory on this map. Check that city’s own housing element or planning department.

ADUs: the rules the state sets

Accessory dwelling units, the backyard cottages and garage conversions also called granny flats, are governed by California law, which cities can loosen but not tighten past certain floors. In general, a city must act on a complete ADU application within 60 days, without a hearing; it must allow at least an 800-square-foot ADU with four-foot side and rear setbacks; detached ADUs get at least 16 feet of height, more near transit; ADUs of 750 square feet or less pay no impact fees; and cities cannot require the owner to live on the property for an ADU. A junior ADU of up to 500 square feet can be carved out of the house, and needs an owner on site only if it shares a bathroom with the main home. Local rules on design, utilities, coastal permits and fire access still apply.

Several cities and counties in Orange, Los Angeles, Riverside, San Bernardino and San Diego publish free, pre-approved or permit-ready ADU plan sets. A site plan, Title 24 energy documents, soils work and fees are often still required, and the plans must be submitted to that city or county. Confirm the current version and site-specific requirements with the city. Official links are on our free pre-approved ADU plans list.

SB 9: two homes, or a lot split

Senate Bill 9 generally requires streamlined approval of up to two primary homes on a lot in a single-family zone, a split of that lot into two, or both, for up to four units in all when ADUs are counted. The usual limits: it applies only in single-family zones; it can be blocked on sites with certain fire, flood or earthquake hazards, farmland, wetlands or habitat; it cannot demolish rent-restricted or rent-controlled housing or a home occupied by a tenant in the past three years; historic districts and landmarks are out; and a lot can be split only once, with the owner generally signing an affidavit to live in one unit for three years. Cities must allow units of at least 800 square feet and cannot require side or rear setbacks over four feet.

Why we do not color lots “eligible.” ADU and SB 9 eligibility turns on zoning, lot size, existing tenants, historic status, easements, utilities and hazard exceptions that no public map on this site captures parcel by parcel. The map’s zoning colors and the fire, flood and fault layers above can flag obvious issues for a first look, but only the city or county planning department can tell you what a specific lot allows.

Property tax, Prop 13 and Mello-Roos in plain English

The 1% base. Under Proposition 13, the general property tax is 1% of the assessed value, and the assessed value resets to the purchase price when you buy. After that it can rise no more than 2% a year while you own the home, unless you add on or remodel. Voter-approved school and water bonds and fixed charges for things like lighting or vector control are added to the bill, which is why most Southern California tax rates land between about 1.1% and 1.3%.

The supplemental bill. Your first regular tax bill may still reflect the seller’s lower value. The county then sends one or two supplemental bills for the difference between the old value and your purchase price, prorated for the rest of the fiscal year. Many buyers are surprised by it, and it is usually not paid through the lender’s impound account, so set the money aside.

The homeowners’ exemption. If the home is your main residence, file a claim with the county assessor and $7,000 comes off the assessed value, about $70 a year off the bill. Many counties mail the form after a sale; file it promptly to get the full year.

Mello-Roos. A Community Facilities District can levy a special tax to pay for the streets, schools, parks and services that newer communities needed. It is a fixed dollar amount set by a formula, not a percentage of value, and many district formulas let it rise each year. On a new home it can add several hundred dollars a month, so it belongs in the payment, not a footnote. Ask for the Notice of Special Tax and the per-lot tax sheet, and enter each CFD in the calculator. Our Ontario Ranch guide walks through a real City of Ontario example.

Renting or buying: how to read the answer

For many Southern California families the first question is not which house but whether to buy at all. With a recent 30-year average near 7.11%, the first-year cost of owning a home usually runs well above the rent on a similar one. That gap is real money. But owning also pays down a loan and, if prices rise, builds equity, while rent keeps rising and builds nothing. The calculator weighs both over the years you expect to stay.

How it works. Month by month, it adds up what an owner pays (principal and interest, property tax, any Mello-Roos, HOA dues, insurance and upkeep) and what a renter pays. The renter keeps the down payment and closing costs and invests them; whichever side has the lower monthly cost invests the difference at the same return. At the end, the owner sells, pays selling costs and the loan balance, and keeps what is left plus any savings. The side with more money at the end comes out ahead. The tool also shows the year when buying overtakes renting under your inputs.

What moves the answer most. How long you stay matters most, because buying and selling cost several percent of the price each way. After that come your rate, the gap between the price and the rent, and how fast prices and rents grow. Property tax follows Proposition 13: the assessed value starts at your price and can rise no more than 2% a year. Rents are different. California’s statewide rent cap limits yearly increases on many covered units to 5% plus inflation, never more than 10%, but many single-family homes owned by individuals are exempt.

What it leaves out. Income-tax effects, mortgage insurance with less than 20% down, capital-gains tax and refinancing are not modeled. Investment returns are not guaranteed, and nobody knows what prices or rents will do. Treat the result as a way to test your own assumptions, then talk with a lender and a tax adviser about your situation.

Prop 19 in plain English: keeping a low tax base when you move

Proposition 13 keeps a long-time owner’s taxable value far below market. Proposition 19, approved by voters in November 2020, decides when that low value can follow you. Since April 1, 2021, a homeowner who is 55 or older, severely and permanently disabled, or whose home was damaged by wildfire or natural disaster can sell a principal residence and carry its taxable value to a replacement anywhere in California, up to three times for the age and disability groups, under California property tax rules.

The value test. The replacement must be bought or newly built within two years of the sale, before or after. If it costs no more than the original home’s value, the old taxable value moves over as is. The allowance is 100% of the original’s value if you buy first, 105% if you buy within a year after selling, and 110% in the second year. Anything above that is added to the transferred value. That is the worked example in the calculator: $600,000 − $420,000 = $180,000, plus the $100,000 taxable value, equals $280,000.

Filing. The relief is not automatic and does not go through escrow. File a claim with the assessor in the county where the new home is, within three years of buying it. If you buy before you sell, the new home is taxed at full value until the original sells. Expect a supplemental bill either way.

Parents and children. Prop 19 also narrowed the old Prop 58 exclusion. For transfers on or after February 16, 2021, only a family home that stays a principal residence keeps the parent’s value, and only up to the parent’s taxable value plus an amount that started at $1 million and is adjusted every two years, now $1,044,586 for transfers from February 16, 2025, through February 15, 2027. The child must file for the homeowners’ exemption within a year and file the family-transfer claim within three years. Rentals and second homes are reassessed.

Before you list or buy: ask the county assessor to confirm eligibility and the transferable value, and talk with a tax adviser. This calculator shows the arithmetic; the assessor decides the result. It leaves out supplemental bills, partial interests, new construction, and similar limits.

How the affordability estimate works

A lender looks at two ratios: the share of your gross monthly income that would go to housing (principal, interest, property tax, insurance, HOA dues and Mello-Roos), and the share that would go to housing plus your other monthly debts. Common published guidelines are about 28% and 36% for many conventional loans and about 31% and 43% for FHA-style manual underwriting. Automated findings can allow more, or less, depending on credit, reserves and the program.

The calculator takes the tighter of those two caps, subtracts the monthly insurance, HOA and Mello-Roos you entered, and solves for the highest price that still fits at your down payment, rate and tax rate. Mortgage insurance, which often applies with less than 20% down, is not included, so an FHA-style result can overstate the price you can support. The default interest rate is a recent national 30-year average, currently 7.11%, not a quote. Treat the result as a planning range and get a pre-approval.

How to read the closing-cost and net-sheet estimates

California county documentary transfer tax is generally $1.10 per $1,000 of the taxable amount (often the price, or the equity if a loan is assumed). Some cities add their own tax. This tool includes commonly published extras for the City of Los Angeles (including Measure ULA tiers on high-value sales), Culver City, Santa Monica, Redondo Beach and the City of Riverside, and it notes that Pasadena and San Diego typically do not add a net extra beyond the county rate. Thresholds and brackets change. Confirm with escrow.

Buyer costs here are a planning range: an illustrative band for escrow and title, a lender-fee assumption you can change, and any other amount you enter. Seller net starts with the price, then subtracts the commission you type, an escrow and title range, transfer taxes, the loan payoff and any other costs. Commission is not a set rate. Prepaid interest, property-tax impounds and homeowner’s insurance vary with the closing date and are only roughly allowed for. Your official Loan Estimate, Closing Disclosure and escrow statements control.

How a California supplemental tax bill is prorated

A purchase usually resets the assessed value to the price you paid. The regular tax roll may still show the seller’s value until the next July, so the county bills the difference as a supplemental assessment for the rest of the fiscal year (July 1 through June 30). If you close from January through May, a second bill often covers the entire following fiscal year, because that roll was already set. A June closing typically affects the next fiscal year only.

This estimator multiplies (new value minus prior value) by the tax rate you enter, then multiplies by the remaining months divided by 12. It is a planning estimate. Exemptions, escapes and the county’s exact month count can change the bill. Set the money aside; a supplemental bill is often not paid through the lender’s impound account.

How to use recorded sales

A recorded sale is a fact on public record: a deed was recorded and, in most cases, a price was reported. That makes it a useful check on asking prices, but it is not a comparable sale until someone confirms the details. Prices can include transfers between family members, partial interests, bulk or portfolio deals, and sales where furniture or credits were part of the deal. The newest sales take weeks to reach county files.

Riverside County recorded sales are included, covering sales from earlier in 2026, with lot and building details. Los Angeles County sales shown are historical and may not include recent transactions. Orange, San Bernardino and San Diego counties do not have sale prices in this tool, and we will not copy them from listing websites, so the tool links to each county assessor instead. For a current comparable-sales report on a specific home in any of the five counties, call or text us; it is free.

Coverage and limits

Maps and planning layers

• Hazard layers are simplified copies of public government hazard maps, for screening only. They are not an official flood, fire or earthquake determination.
• Schools: public school locations and district lines. Attendance areas, where shown, are historical and may not match current assignments. Confirm the assigned school with the district, for example with LAUSD’s Resident School Identifier or San Diego Unified’s School Finder. School reports: California School Dashboard.
• Housing Element sites come from public planning inventories. A listing is not a permit. Coverage gaps are listed in the housing section.
• Zoning density: see the zoning map guide. Basemap © OpenStreetMap contributors, tiles by OpenFreeMap. The commute map uses the same basemap; drive times are typical ranges, not live traffic.

Calculators

• The payment, buydown, rent-vs-buy, Prop 19, affordability, closing-cost and supplemental-tax tools are estimates only. They are not tax, legal, insurance or lending advice, and they are not a loan quote, net sheet or tax bill. Prop 19 leaves out supplemental bills, partial interests, new construction, and similar limits. Confirm taxes with the county assessor and payments with your lender or escrow officer.
• The default interest rate is a recent national average for 30-year fixed loans, currently 7.11%, not a quote. Starting examples follow our November 11, 2026 Ontario Ranch brief. Other defaults are stated planning assumptions.

Recorded sales

• Riverside County: public records of residential sales from earlier in 2026. Multi-parcel documents and transfers under $10,000 are left out. Look up a sale with the county assessor.
• Los Angeles County: historical public records that may not include recent transactions. Look up a sale with the county assessor.
• Orange, San Bernardino and San Diego counties do not have sale prices in this tool. Look up a property with the Orange County, San Bernardino County or San Diego County assessor.

Questions about a specific home? Call or text 833-THIS-BROKER (833-842-7465), text us, or request a call. Dr. Hamid Rowshan, Choice of America. DRE #02004794, company DRE #02240008.