Building an ADU sounds straightforward in theory, but in reality, it can be very challenging.
Problems can arise in each step, from issues with permits to delays in construction.
The overall time to complete an ADU project can vary significantly based on such factors. On average, it can take anywhere from 9 to 18 months, with some exceptions below and above that range.
Key Phases in ADU Construction
There are three main phases to ADU construction.
These include the initial planning and design phase, which is usually one of the most excising. After that comes the frustration of getting permits and approvals, which can be a bit of a headache, and then lastly construction which can either be a breeze or difficult depending on your contractor.
It isn’t just a case of starting construction right away, so let’s see what’s involved in each stage.
Planning and Design (1-3 Months)
The planning and design phase is where your ideas come to life.
It involves creating detailed architectural plans and ensuring the scope of the project is both reasonable but also realistic to actually build. Some people opt for pre-approved designs to speed this process up, but working with a custom ADU builder can help when it comes to adding your personality to the ADU.
- Site Assessment – This involves choosing the best location for the ADU to be built. b considering several things such as access, privacy, and other buildings.
- Design Development – Working with an architect to create detailed plans. This stage involves multiple iterations to balance homeowner preferences with regulatory constraints and budget considerations.
Permitting and Approvals (2-6 Months)
Obtaining permits and approvals can be one of the most time-consuming aspects of building an ADU.
This step is crucial though, without the correct permits and approvals your build will only be delayed even more.
- Zoning Approvals – Ensuring the project complies with local zoning laws. This may involve public hearings or variances if the proposed ADU does not conform to existing zoning rules.
- Building Permits – Acquiring necessary construction permits. This step verifies that the ADU design meets all safety and building standards.
- Utility Permits – Securing permits for electrical, plumbing, and other utilities. This ensures that the ADU will have adequate and safe utility connections.
Once these are in place, it’s time to actually start construction.
Luckily, this usually doesn’t take as long as building an entire house from scratch.
Construction (4-9 Months)
The construction phase includes site preparation, foundation work, building the structure, and installing utilities.
- Site Preparation – Clearing and leveling the site. This may include demolishing existing structures or landscaping that obstructs the new construction.
- Foundation Work – Laying the foundation. The type of foundation depends on the site conditions and design of the ADU, ranging from slab-on-grade to raised foundations.
- Building the Structure – Framing, roofing, and exterior work. This involves erecting the walls, installing windows and doors, and completing the exterior finishes.
- Utility Installation – Connecting water, electricity, and sewage. This phase ensures that the ADU has all necessary utilities, which may require trenching and coordination with local utility providers.
- Interior Finishing – Installing fixtures, flooring, and final touches. This includes everything from drywall and painting to installing kitchens and bathrooms.
This phase can be influenced by factors such as weather conditions, availability of materials, contractor schedules and much more.
4 Factors That Influence ADU Construction Time
These are the top 4 most common factors that influence the time it takes to build an ADU.
1. Local Regulations
Local building codes and zoning laws significantly impact the timeline.
Cities with streamlined ADU regulations, like Portland and Los Angeles, tend to have shorter approval times. Others might not be the same though, so be prepared to do some research and use your patience in this part of the process.
2. Design Complexity
The complexity of the ADU design obviously affects construction time.
Custom designs with unique features will naturally take much longer than a pre-approved, more standard design.
Also consider that JADUs will take much less time to construct as they are smaller, while DADUs often take longer.
3. Contractor Availability
The availability and efficiency of contractors play a crucial role in any ADU project.
If you choose a contractor who is trying to handle multiple projects at once, you may end up being delayed. There is clearly a balance here with choosing someone reputable, but also someone who has time for your project as well.
Choosing contractors with specific experience in ADU construction can also streamline the process, as they are familiar with the unique challenges and requirements of these projects.
4. Site Conditions
The last thing to keep in mind with the timeline of an ADU project is the site conditions.
If lots of pre-site work is required, like laying more challenging types of foundations to deal with steep slopes or dealing with poor-quality soil, this can add to the total time it will take to make your dream a reality.
Financing Options for ADUs
When it comes to financing an ADU, there are a few different routes you can explore.
We have a full guide on it here if you want more information, but the points below summarise the choices well.
Home Equity Loans
Homeowners can use the equity in their existing property to finance the construction of an ADU.
Home equity loans often offer lower interest rates compared to personal loans, making them a cost-effective financing option depending on your circumstances.
Government Grants and Incentives
Some local governments provide grants and incentives to encourage the development of ADUs, so always keep up to date with any new laws being introduced that might make your life easier.
For example, the California Housing Finance Agency provides grants of up to $40k to reimburse ‘pre-development and non-recurring closing costs associated with the construction of an ADU’
Tips for Expediting ADU Construction
If you want to build your ADU in a shorter timeframe, these tips will help.
Early Engagement with Local Authorities
Initiating discussions with local building departments early can clarify requirements and streamline the permitting process.
Understanding local regulations and potential hurdles beforehand allows for better planning and avoids last-minute surprises.
Leave The Hassle to The Pros
One of the best pieces of advice is to work with an ADU builder who has experience with custom ADU projects in your location.
This will mean they have experience with local regs, and will be able to make your dream become a reality with much less stress.
Using Pre-Approved Plans
Some municipalities offer pre-approved ADU plans that can expedite the design and permitting phases.
Utilizing these plans can significantly shorten the approval process and ensure compliance with local building codes. You can also use Presite to quickly generate ADU site plans, which can also help speed up this part of the process.