ADU Building Process

When it comes to building Accessory Dwelling Units, it is not hard for homeowners to understand whether or not they actually need one. The most complicated part is related to the construction process itself, which is why clients usually delay the whole project.

However, once they learn that there is nothing to be afraid of as long as they have a team of professional contractors behind their backs, all the worries fall away.

And if you are one of such homeowners that want to know more about the construction process of an ADU, then you might want to keep reading this article further, as we will provide you with a step-by-step guide!

ADU Construction Steps

First of all, you need to decide for yourself what kind of Accessory Dwelling Unit you would like to create on your property lands so that when you would come to a construction company like ADUBUILDERSUSA, you can give them at least some information about the project that they could improve.

You might want to think about whether you would like to build a detached ADU or an attached ADU, what size of a new living space you would want to create, what designs you prefer to be implemented, and so on.

And once you have created an overall idea of an ADU project that you want to create, you could come to a construction company. Here is the list of all the steps that they are going to take you through:

  • Initial Consultation

Well-established companies like ADUBUILDERSUSA usually provide their new clients with a first free consultation, where they can get acquainted with each other, learn about the new construction project that a family wants to create, and provide the answers to all of the questions that the clients have.

The first consultation is always a win-win situation: homeowners could resolve their fears, and contractors could understand what kind of ADU projects a family wants them to make. If everybody is satisfied at the end of a consultation, then any further steps could be taken by them together.

  • Deciding on the Financing Options

Once the family has decided that they would like to continue working with this general contractor, they need to decide how they are going to finance the whole project. In case they have their own savings that could cover all the costs for an Accessory Dwelling Unit to be created, then the homeowners could simply skip this step.

However, in another case, third parties would need to be involved in the process. After your initial consultation with ADUBUILDERSUSA, you will not only receive a free estimate of the whole project but could also ask us to give you a list of lenders that we would recommend you to consider for an Accessory Dwelling Unit project to be implemented.

  • Signing the Proposal

The proposal of a general contractor gives you an overview of the entire project budgeting, including the fee schedule of the company and each step of the construction process that would take place on your land.

And as this is still an overview that is simply needed for you to understand the budget that you would need and the amount of time the project could take, it would not include the final pricing.

While working with professionals like ADUBUILDERSUSA, you will not have to worry about things like an interior electrical panel or construction of exterior walls; all will be stated in the proposal and taken care of for you!

  • Going through Feasibility Study

This step, in comparison with the previous, specifically allows us to create a final budget for the whole project, as we now could check your local required permits and the site conditions that your living space has.

For instance, we could estimate the condition of your existing utilities and see the land that we are going to work with so that the foundation footings could be updated if a clear and flat surface is not your case.

At the end of this step, you should receive the locked construction costs of your building plans.

  • Finalizing the Construction Documents

Once every detail is overseen by us and your approval is received, we can finalize all the construction documents together with our architectural drawings and submit them to receive building permits from your city authorities. If necessary, the same submittal package can be sent to your loan lenders.

And while the construction documents are going through a permitting process, you can finalize your choice of materials for the project so that all can be done faster. You can either choose one of our standard designs for your prefab ADU or create an entirely new design of a custom ADU with the help of our professionals.

There are lots of regulations placed in almost any city about building an ADU on your property. For instance, they can restrict you from building an ADU that is over two stories in height or tell you to place an additional parking lot near your own ADU.

What is more, your construction footings will also be inspected by the authorities, and they will look at the structural rebar, vapor barrier, and wire mesh that is placed in the foundation of a new house.

  • Permitting the Whole ADU Process

Once the construction documents are approved, and your design choices are established, we can create overall ADU plans that could be sent to the local authorities for a final inspection.

In this step, some additional fees would need to be paid by you to the city inspector for the full evaluation of the project proposal and the permits that would be received by you afterward.

As you can see, building an ADU is not an easy process, which is why you should always rely on your team of professional contractors like ADUBUILDERSUSA to do the whole job: homeowners do not know all the peculiarities that appear while they are building an ADU, which is why a lot of rookie and expensive mistakes could be made.

  • Building an Accessory Dwelling Unit

Once the permits are received by us, we can finally start to build an ADU for you! During this process, little to no collaboration with you is needed, as it all will be taken care of by your general contractor. Once the guest house construction has started, you can simply relax and wait for your team to finish the process.

It usually takes us around 4 to 6 months to create a custom ADU for you, but the exact amount can vary quite drastically depending on the amount of work to be done and the jurisdiction that is placed in your place of residence.

After that, you can take a final look at your own Accessory Dwelling Unit and accept the job made by us!


Now that you know all the steps that should be taken by a remodeling company during the project implementation, you could start to search for the perfect team that would help you throughout each of the steps.

You might want to consider ADUBUILDERSUSA for a new ADU project to be implemented near your main house, and here are some reasons why other people prefer to hire us for their custom or prefab ADUs:

  • ADUBUILDERSUSA has been on the construction market for many years, which means that the company has a lot of experience dealing with standard ADU plans that include an evaluation of your local building code as well. Therefore, no matter whether you would want to make a garage conversion ADU or a detached, independent housing, we are a team that could help you with that!
  • The portfolio of the company is filled with many successful projects and is always available for the clients to look through. In there, you would find projects of various complexity: from simple garage conversions that do not need their own water supply lines or a foundation slab to detached ADUs with a separate floor plan and underground utilities;
  • The company takes its projects seriously, which is why you can rely on us to do the whole job from the beginning to the end. However, we can also provide you with some separate services that you might need, such as rough electrical or rough framing plans, interior painting, tree removal, and so on.

Give ADUBUILDERSUSA a call today, schedule your first appointment with us, and receive answers to all your questions!

Frequently Asked Questions — FAQ

What’s one drawback of an ADU?

The amount of time spent planning it. While a new ADU or ADU conversion could be built within 4-6 months, it takes additional six months to create a construction plan for every square foot of your ADU, taking into account your plumbing lines, electrical wiring, and lots of other things that should be documented in order to submit plans to the authorities and receive permits from them. Even the exterior paint of your project could matter.

How do I start with ADU?

Your first step should be related to your overall desires for an ADU that you want to make. For instance, whether you simply want to convert your already existing garage, increase your primary residence with the help of an attached ADU, or create a completely independent house in the form of a detached ADU. After this is decided, you need to find a proper construction company and contact them for a further discussion of the physical characteristics that your main residence has.

Do I need a permit to build an ADU in California?

Yes, you do, and the regulation can vary from one part of the state to another. Collaborating with a professional contractor will save you from the need to investigate your local regulations so that you can get your project pre-approved and start construction of your garage conversion ADU or any other ADU much faster!

How long does it take to build an ADU in California?

The whole process could take up to 18 months, and it will include not only the construction period but also the time that is necessary to design and permit your ADU projects. However, please remember that the time frame stated here is the one that is possible only when working with a professional contractor. In other cases, you will need much more time in order to create an ADU.

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