Whether you’re building a new home or considering an addition, one thing is for sure: You need to know how big the home can be. But finding that out is neither fun nor fast. Zoning analysis takes a ton of time, effort, and mathematical wizardry.

That’s where UnderBuilt comes in—you enter an address or APN number into our search bar and we provide an instant report detailing a home’s zone, along with property and size allowances.

Trust us, you don’t want to crank this stuff out yourself. To prove it to you, let’s go over the process of figuring out max build size.

New House Build

Zoning analysis basically means comparing existing conditions with allowable conditions. The end result reveals the expandable or buildable area of your home on any given lot, or as we like to say, its maximum property potential.

You’ll need these two items to figure out how big your home can be:

  • Property Survey
  • Zoning Map

Property Survey

The existing conditions of your home are pretty straightforward. These are found in your lot’s official property survey, which details land placement and property lines. Often, a property survey comes bundled with all the other paperwork you get when buying a home. If it didn’t, tracking one down can be a pain and usually involves time consuming visits to your local zoning offices. And it must be current; if your home has a feature like a deck, garage, or patio that’s not included in the survey, you’ll need to hire a property surveyor to create an updated survey.

Zoning Map

Los Angeles Zoning Map

A zoning map clearly defines the boundaries of a given district, and you’ll need to look at one to find which zone your property falls in. Zones are grouped by their shared rules and regulations. For residential properties, zones are designated by the letter “R” followed by some numbers and/or letters. For example, “R1” could be a zone containing typical single-family suburban homes with a moderately sized structure, a yard, and a few trees. Although the exact regulations for a specific zone vary from city to city, an R1 property generally has one free-standing main residence that cannot exceed a maximum height, must be set back a minimum distance from the street and neighbors, and must include a driveway or garage. Other zones, like R2, R3, and RE, all have different requirements and rules.

You may be able to access a zoning map online; for example, the Los Angeles Department of City Planning provides the online tool ZIMAS. But sometimes you’ll have to visit your local zoning office to buy a map.

Putting the Two Together

Once you know what zone your home is in, you’ll need to apply the current regulations, rules, and requirements (a.k.a.. zoning ordinances) for your area. Since zoning codes constantly change, a home that once met all the requirements of the zone may find itself left out in the cold. Those now-defunct existing conditions will mean that any new additions or builds may not be possible. For example, if your home falls inside a recently instituted setback requirement, you may not be able to build a second story over that area.

Or maybe you’re looking to extend the front of your home, but because the structure has to be a certain distance from the street the current ordinance won’t let you build as big as you wanted. This is where the existing conditions laid out by the property survey and the allowable conditions figured out by the zoning maps come into play. Together the two help determine how big your home can be.

A Third Option

You could go through all these steps, take a trip to your local city planning department, hire a surveyor, click your way through screen after screen of confusing numbers, have a sit down with your friendly resident zoning officer, and try to wrap your head around all the regulations while taking into account the most recent changes such as the major ones just implemented by the city of Los Angeles.

Or, you could use a secret weapon: UnderBuilt. 

The choice is yours! 

UnderBuilt Mobiel Report