Everything You Need To Know About Home Additions in Los Angeles [Updated for 2024]

If you’re a Los Angeles or Southern California homeowner and you need more space in your home, one option is buying a larger house. Alternatively, you can build a home addition in order to create more living space. A one or two-story home addition is a good opportunity to increase your enjoyment of your home and add value to the property when you decide to sell it.

One Story Home Addition

Here at GreatBuildz, we speak with clients every day who are considering a home addition project. GreatBuildz is a free service that connects homeowners with reliable, pre-screened home addition contractors, then provides ongoing project support to ensure a stress-free experience.


In this blog, we’ll share some ideas, costs, and tips about adding different types of additions to your home and finding the best contractors for your project.

How much does a home addition cost? 

You can expect an average home addition to cost anywhere from $200 to $400 per square foot.

Home additions can vary substantially depending on what you want to do to your home. They can span from a small bathroom addition all the way up to a full second-story addition. Let me discuss the most popular types of additions to a home and their average costs. Please keep in mind building costs vary significantly by graphic region, so the costs below pertain specifically to Los Angeles and Southern California homeowners.

Costs for a Master Suite Addition

The price for a master suite addition in Los Angeles and Southern California will range from $150,000-$200,000

Home Addition Closet

A common average cost and a good budget to start with is $150,000. A master suite floorplan can be as small as 300sf on the small end, but most additions are 400-500sf or even larger.  A common size for a master addition is 20x20ft or 20x25ft but it can easily be any unique dimension. Prices are similar for a full guest suite or in-law suite. This price assumes a single-story addition.

Bathroom Addition Costs

Building a bathroom addition to your existing home will cost you between $50-100k.

The price of a new bathroom will depend on its size and amenities. Clearly, a half-bath with only a toilet and sink will be less expensive than a full bathroom with a tub or shower. Finally, a luxurious, master bathroom will come with the biggest budget. The average cost will also depend on the location of your addition and how far it is from the nearest plumbing connections/etc.  

How much does a kitchen addition cost?

Home Addition Floral Kitchen

A kitchen addition will range in costs from $100,000 – $120,000 on average.

A kitchen addition is really a kitchen expansion or relocation, but it still requires the demolition of the old space and the creation of a new kitchen in the additional or expanded space. Generally, a kitchen is an expensive space to renovate by itself because of cabinets, countertops & appliances. Plus, a kitchen addition/expansion requires new plumbing, electrical, gas, etc.  

Bedroom Addition Costs

Home Addition Bedroom

A simple room addition should cost $40-60k and is the simplest room to build.

Whether you’re building a bonus room, guest room, office, or other space, this room addition is the lowest cost because it requires no plumbing and no gas connections (it’s a dry room). Of course, the cost will depend on the size and would increase if you include enhanced details like built-in cabinetry or closet cabinetry, etc.

Cost of a Second-Story Addition

Home Addition Two Story Home

A second-story addition will cost at least $100/sf more than a traditional single-story addition, so typically range from $400 – $500 per square foot.

A second-story addition will always cost more because of the extra work required to support the extra weight of the new second story.  This might include reinforcing the foundation of the home, adding structural support to the first floor walls and structure, adding beams, etc.

Other extra costs include tearing off the first-floor roof and rebuilding a roof on top of the second-floor additional rooms. You’ll also need to build a new stairway up to the second floor and do some potential reconfigurations of the electrical, plumbing, and HVAC systems. Finally, most people find that they have to do some demolition and reconfiguration of the first-floor layout just to accommodate the stairway and second-story space.

Please keep in mind that although you can start your budgeting research with a basic cost calculator above, the best way to get real, accurate cost figures is to discuss your project and/or plans with a few good general contractors.     

How to start planning a home addition?

Home Addition Purple Living Room

Once you have some idea of the cost and budget for the addition you want to add to your home, the next step is starting to plan the possibilities. After doing some research, you’ll want to make some general decisions about the size and location of the future space you want to add to your home.

Think about how it will function for you now and into the future; As well as whether the space will be valuable to a future buyer of your home. If the room addition is functional and well-built, it will add significantly to your resale value. But, you don’t want to create a house that’s ‘overbuilt’ for the neighborhood by size or bedroom count. 

You’ll need to understand the zoning in your area and determine whether you have the room in your on your property to build the addition that you desire. There are two good ways to figure out your options for a room addition.

First, you can go down to your city building department and ask them to provide you with guidance in terms of the zoning and requirements. Alternatively, you can contact a local architect or designer and ask them to come to your home to review the possibility of creating a home addition on your property. A good local contractor can also help guide your decisions at this early stage and also inform you about realistic budgets from their recent projects. 

You’ll also want to consider whether you can continue living in your home while the home addition is under construction. If the additional area is separate from your main house you might be able to live through it. However, something like a major or second-story addition would be very challenging or impossible to stay in the house. Building a major addition might be disruptive to your life, so it makes sense to plan ahead for your living arrangements.  

Room Addition Ideas

Kitchen additions (& expansions):

Home Addition Kitchen

For many homeowners, the kitchen is the heart of the home. But in many older homes, the kitchen is small and closed off – this is extremely common among the classically small LA homes. With today’s trend of large open kitchens for entertaining family and friend gatherings, people are deciding to expand their kitchens by adding space.

By building a kitchen addition/expansion, you can create a large elegant space with room for things like an island or walk-in pantry. You’ll probably need an architect or designer to help draft a home addition plan to create a functional new kitchen layout.

Bathroom additions:

It’s not unusual for older homes to have a limited number of bathrooms and therefore a new bathroom addition is a common project. Adding a bathroom to your home can help solve the practical problem of too many people sharing too few bathrooms, but it can also greatly improve resale value. Many homeowners and homebuyers want to see a sufficient number of bathrooms so that adults, kids, and guests don’t need to share them.

Bathroom remodels can be as simple as adding a powder room for guests or significant projects like large, elegant master bathrooms. The average cost for a bathroom will always be more than a bedroom because of the need to run water pipes and waste lines.

Bedroom or home office addition:

Home Addition Office Space

Many Los Angeles and Southern California homeowners find that their family needs outgrew the number of bedrooms in their home. If they don’t want to move, they can simply add more space to their home, assuming they have the room to do so. Adding one or more bedrooms will add to the practical use of the home as well as its resale value.

Simple spaces like a bedroom can also function as a home office, guest room, or other use. Ideally, any such space should be planned with a closet so that future buyers are willing to pay for the higher bedroom ‘count’.  Unlike a bathroom or kitchen, this is the simplest and cheapest addition to build because there is no need for water & waste lines. 

Master bedroom suite addition:

Home Addition Master Suite

Many older homes were built without a true master bedroom suite. So, adults might have to share a bathroom with the kids (not fun).

Although this was the case many years ago, lots of homeowners today want to have their own private master bedroom suite and its own elegant, private bathroom and walk-in closet. Therefore, the master suite addition is a common home improvement project, even though it may come with a substantial cost due to its size. Sometimes, people even decide to add a 2nd story addition to accommodate a private master suite.  

Addition above a garage:

Garage Home Addition

Sometimes it’s possible to add space to your existing home. Depending on the location of your garage, you may be able to add living space over your existing garage. Creating an addition over a detached garage is sometimes known as a granny flat or Accessory Dwelling Unit, which is very popular recently after the law changes in California.

Although the first-level garage structure may need to be strengthened or ‘braced’ for the extra load on the second floor, this added living space can be added without losing any of your lot areas. 

Attached ADU addition:

With the new laws regarding ADUs in California, many homeowners are choosing this sort of addition for their property. An attached ADU is essentially a second home or full living unit that’s attached to your main home. It got its own separate entrance and all the comforts of a small house with its own kitchen, bathroom, sleeping area, etc.

Many ADUs ranges in size from 250sf all the way up to 1,200sf.  They can be used in a multitude of ways including housing families, seniors, post-college age kids, or as a rental home for additional income. 

An attached garage conversion into a JADU is another option. Its not exactly an addition, because you already have an attached garage and are converting it into living space. But, that’s actually a pretty major benefit and leads to cost savings. A JADU (junior ADU) can be up to 500sf in size and is intended to be its own separate living unit with a bathroom and small kitchen. Essentially a garage conversion to a JADU will be 350-400 studio ‘apartment’ that’s ideal for a single person or a couple without children.

Living room, family room, or bonus room addition:

Home Addition Living Room

Much like a bedroom addition, adding a living room or family room is on the cheaper side of building on to your home because it doesn’t require water or waste-lines like a bathroom. Simply put, these types of rooms are essentially four walls and a roof. You will still want to consider decorative items like lighting, built-in cabinetry, as well as HVAC vents in these rooms.

It’s important to research the right size for your desired use because these types of rooms can range greatly in size. You don’t want to end up with a room that’s too large or too small compared to the rest of the house.

What To Consider When Planning a Single-Story Home Addition

When you’re planning to add a one-story addition to your home, the likely location for it is in the back or the front of the home (usually not enough room on the side). That means you need to have space in your front yard or your backyard to build the new addition. Plus, most cities require a ‘setback’ from your front or rear property line (an area you cannot build).  So, step one is to understand if you have the room within your yard to create the desired additional living space.  

Another important factor is to determine how this new addition space will ‘connect’ to the rest of the house. You want the floor plan of your enlarged home to flow and feel practical. You don’t want strange connections between rooms like adding a bedroom next to your kitchen, for example. Early on in the process, you’ll need to engage an architect to draw your existing house layout on a simple plan and then determine how an addition could connect with that layout.

It’s quite possible that areas in your existing home may have to be reconfigured to accommodate your desired addition. Keep that in mind when you’re budgeting…any reconfiguration of your existing home layout will be an added cost to the actual addition itself. 

What To Consider When Planning a 2nd Story Addition

Home Addition Staircase

Hiring a competent architect is imperative when you’re planning for a second-story addition. The architect will also need to bring in a structural engineer to determine the requirements to brace the first level for the added weight on top. A good architect will work with you to design a home addition plan that accommodates a staircase somewhere on the first floor while also keeping your first-level floor plan functional.  

A second-story addition is a major project that will take a significant amount of time and make it challenging for you to stay in your home during construction. Especially at the beginning, the contractor will need to tear off a portion of your roof and do some significant work on the first floor. Later in the project, once the framing and roof are complete, it may be easier to live inside the house during construction.

What’s the process to build a home addition?

Once you’ve decided to start working towards a home addition, it’s a really good idea to meet with both architects and contractors to find the right fit for you. Sometimes you might want to start by meeting contractors, and the one you select can bring in an architect with whom they have a relationship.

It’s not advisable to start by just hiring an architect to draw your home addition plans. You may find that when the plans are complete, the construction estimates you get from contractors will be higher than your budget; and you’ll need to redesign your plans to align with your budget.

In order to keep your home addition costs reasonable or affordable for you, always engage at least one contractor throughout the plan design process. I would not suggest relying on a home addition cost calculator you find online because every project is different and costs vary greatly depending on where you live.

A Few Home Addition Tips Before You Get Started

Home Addition Permit Costs

  1. Don’t forget to budget for the costs of city plan check, permit, and any other impact fees your city will charge to allow for this construction. 
  2. Always budget for a 10-20% contingency on top of your contractor’s estimate. If you don’t use it, you can be pleasantly surprised. But, in a majority of projects, things will come up that you didn’t envision that will add costs to your project.
  3. The more detailed you are upfront about your project scope and materials, the fewer changes will be necessary during construction. And changes are always expensive and cause delays.
  4. Don’t forget to add this additional space to your homeowner’s insurance policy when the project is complete. Also, let your insurance agent know when you’re starting to build to ensure you’re covered against any perils during construction.

How to finance a home addition?

Home Addition Financing

While some people have saved up enough money to pay for an addition from their own savings or investment account, the average cost of an addition is so high that you may need to seek financing. There are multiple options to consider when looking to get a home renovation loan for an addition project. Remodeling financing options include a construction loan, renovation loan, refinance, and others. Check out our blog all about renovation financing for details on all the various loan options.  

How do I find a home addition contractor near me?

Home Addition Contractor

There is only one type of contractor that is qualified to build a home addition and that’s a general contractor. No other type of contractor is licensed to qualified to do this complex construction project. And don’t even think of hiring an unlicensed or uninsured contractor to build your home addition.

The best way to find a great general contractor is to ask friends or family for a recommendation for someone that they know or have used in the past.  If your contact had a good experience with a general contractor, you can be relatively certain that this contractor will probably also do good work for you.

If you can’t get a good recommendation from friends or family, our staff at GreatBuildz can connect you to a few reputable, local general contractors that are capable of building a home addition in your area.

A home addition is a significant, costly and time consuming project. Therefore you’ll want to make 100% sure you’re working with a legitimate and reliable contractor. Before you decide on a contractor, check the CSLB site to ensure they have an active license without any complaints. Also, ask the contractor to provide you evidence of insurance, including both general liability insurance and workers compensation insurance. Ask their insurance broker to add you to the policy as ‘additional unsured’. On the topic of insurance, you might consider calling your home insurance agent and letting them know you are about to embark on a home addition so they can advise you on any insurance changes you will need to make before and after construction.

When it comes to planning and coordinating a home addition on your property, you shouldn’t have to go it alone – GreatBuildz can help simplify your renovation experience.

GreatBuildz is a free service that connects homeowners with reliable, thoroughly screened general contractors and provides project support from start to finish. Call now (818.317.3567) to chat with a real person about your next renovation project or visit our website for more information: www.greatbuildz.com.

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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