How Big Can You Build On Your Residential Lot in Los Angeles?

A new home construction is one of the biggest steps you can take in your life. Most people, reasonably so, wish to fulfill their idea of a perfect home, and get as much value from the square footage as possible. It’s also reasonable that most people wish to build big, after all, if you have the resources for it, why would you not? 

The size of a building, however, is usually one of the first places future homeowners encounter obstacles. It’s hard to get the right information, and it’s often unclear where to look or who to ask. 

We prepared a list of basic guidelines for Los Angeles residential home size, but be aware that home size is subject to highly complicated rules. This article should help you get the right information and make informed decisions about planning your future home. 

To begin with, we should take a look at the legal building size restrictions in Los Angeles based on zoning code guidelines.


Los Angeles Zoning Explained

Zones define the type of buildings that can be constructed in the area, as well as their minimum and maximum size, usually relative to the size of the lot. Other important things defined by the zoning code include – building density, floor-area ratio, height, setbacks and parking regulation. 

The first step to planning a new building on your lot is to identify the zone the lot belongs to, so other regulations can be determined precisely. The Los Angeles zoning code defines land areas by their primary purpose, which can be residential, commercial, industrial, and other. Even these zone classes have subclasses too. In this case, since we are analysing home construction, let’s focus on the residential zone and it’s subzones, especially the R1 and its variable zones.


Residential Zones in Los Angeles

If you don’t know the exact zone your lot belongs to, you can find out more by visiting the Los Angeles Department of Building and Safety. As for residential zones, they are divided into single-family and multi-family zones. As the name implies, these zones dictate how many dwellings may be constructed on a single lot in that area. Naturally, single-family zones allow a single dwelling on the lot, regardless of its area, and multi-family zones allow multiple dwellings, one for each family occupying the lot. 


Single-family Residential Zones in Los Angeles

Most lots in Los Angeles belong to the single-family R1 residential zone. As discussed, this implies that a single dwelling may be constructed on them. Of course, in cases of big lots in the single family zone, it’s possible to divide them into smaller sections, and then build a family dwelling on each of them. This practice is commonly known as subdividing, and it’s how most of Los Angeles residential areas have been constructed in recent history. 

Odds are that your lot is also a residential single-family lot, belonging to the R1 category. Also, since 2017 Code Amendments in Los Angeles, a subset of zones was created inside the R1, known as R1 variable zones. Two very common variable zones are RA and RE, referring to residential agriculture, and residential estate zones. 

With zoning out of the way, let’s analyse the size requirements your building will need to comply with.


Single-family Zone Residential Building Requirements

The following are important square footage, setback, height, and other requirements, which may vary depending on zoning:


Residential Floor Area (RFA) Requirements

Floor area requirements are based on the percentage size ratio of your lot’s square footage. For the R1 zone, you may have up to 45% of your lot as your residential floor area. RFA varies for the variable zones, in the range of 20% up to 65%

The floor area also includes any attached accessory buildings, while detached ones are exempt as long as their total floor area doesn’t exceed 800 sq. feet and 16 feet in height. Outdoor spaces like porches and patios are also included, but only if they feature a solid roof. Keep in mind that under some circumstances, parking or driveway space will also be included in the RFA calculation. 


Building Height and Encroachment Plane Requirements

The maximum allowed building height depends greatly on the roof slope portion. Roof slope height is obtained by subtracting the encroachment plane from the total height of the building. 

Below is a summary of maximum height limits for different height categories of roof slope.

For R1, RS, and RE9 Zones:

  • Up to 28 feet when the roof slope doesn’t exceed 25% of the total height. 
  • Up to 33 feet when the roof slope portion is equal to, or greater than 25%

For RA, RE11, RE15, RE20, and RE40:

  • Up to 30 feet when the roof slope is less than 25%
  • Up to 36 feet when the roof slope is equal to, or greater than 25%

Front, Side and Rear Setback Requirements

By definition, a setback is the distance from a structure, or an area that may be constructed on, to the property line on the same side of the lot. Setbacks are dependent on the dimensions of your building, so to know the exact setbacks your building will require, you will need to have first established RFA calculations

Some universal rules that apply to Los Angeles residential homes are the following: 

A residential home in Los Angeles must have a front, side, and rear yard

  • The front yard must have a depth of at least 20 feet.
  • The side yard must have a minimum depth of 5 feet.
  • The rear yard must have a minimum depth of 15 feet

Each of these yards requires a setback based on the building size, as well as the size of the prevailing setback. The prevailing setback is one of the most common points of confusion for home construction, as it’s based entirely on the average setback of buildings in the surrounding area, such as the city block. In some cases it can be hard to properly establish the prevailing setback, as it’s not always set in stone. Professional help is key to establishing proper setback calculations, but for the purposes of this article, here are some simple guidelines.

  • The Front Yard setback must be at least 25 feet, or 20% of the lot’s depth, whichever is smaller. This holds true as long as it also complies with the prevailing setback of the area.
  • The Side Yard setback must at the minimum be 10 feet, if the building doesn’t exceed 18 feet in height. If it does exceed 18 feet, the setback must increase to compensate. The setback increases by 1 foot for each 10 feet of height the building has over the initial 18 feet.
  • The Back Yard setback is similar to the front yard setback, but with the difference that the prevailing setback is completely omitted from the calculation. 


Some guidelines of the potential maximum size of your future building are possible to establish without researching in-depth, but the permitting process is often full of obstacles. Without professional help, you are unlikely to properly assess the possibilities for your future home, and even less likely to take full advantage of your lot’s zone and area. 

Planning a big home construction is done on a case-by-case basis, and it’s unlikely that you will find the right information for your particular case online or over the phone. Not to mention that some aspects of planning, such as the prevailing setback, are entirely based on professional observation, and are not easy to identify. 


Contact a Professional and Get Precise Information 

Even the Los Angeles Department of Building and Safety may not give you ideal information on first contact, as there is a lot to process for each lot individually, including any unusual aspects or oddities. We recommend that you get professional help directly, and take advantage of Yakov Build’s extensive experience in new home construction. 

Yakov Build offers to complete the whole process of evaluation, planning and permitting for you, helping you get the maximum home square footage out of your lot. We enjoy building big too, so don’t hesitate to contact us via phone and discuss your plans with us further. 

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