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Kickstarting Your ADU Project: Budgets, Timelines, and Site Prep

Building an Accessory Dwelling Unit (ADU) can be an exciting venture, offering not only an additional living space but also a potential source of income or a place for loved ones. However, kicking off your ADU project requires careful planning and understanding of budgets, timelines, and site preparation. In this blog post, we’ll guide you through these initial but crucial steps of the ADU creation process with BuildHers Blueprint. 


Setting Your Budget

The first and perhaps most important step in your ADU project is establishing a realistic budget. The cost of building an ADU can vary significantly based on size, location, materials, and labor rates. To avoid any financial surprises, consider the following:


1.     Construction Costs: Get multiple quotes from contractors and ensure they include all aspects of building, from foundation to finishes.

Cost Per Square Foot: To gauge the potential size of your ADU, take your maximum budget and divide it by at least $275. This gives you a realistic perspective on the size of the ADU you can afford. For example, if your budget is $110,000, dividing by $275 would suggest you could afford to build a 400 square foot ADU.

2.      Design and Permitting Fees: Account for the cost of architectural designs, engineering, and permits which can be a significant portion of your budget. These fees are not static and can escalate depending on the size of your ADU:

Size-Dependent Fees: Be prepared for the possibility that permit fees may increase with the size of your ADU. Particularly, if your unit exceeds 750 square feet, you might cross a threshold that triggers additional costs.

Impact Fees: For larger ADUs, local municipalities may charge impact fees. These are meant to offset the additional public services your new unit will require.

Educational and Recreational Fees: Furthermore, building a sizeable ADU could mean paying school fees, contributing to the funding of local educational infrastructure, and parks and recreation fees, which support community leisure spaces.

When planning the size of your ADU, remember that the larger the footprint, the higher the potential for increased fees. These extra costs, such as impact, school, and parks and recreation fees, are essential to consider in your overall budget as they can add up and affect your financial planning.


3.      Utility Connections: Navigating utility connections for your ADU project is an area that can significantly impact your budget, depending on what your local regulations dictate:

a.     Utility Connections: The expense of connecting to municipal water and sewer systems can add a considerable amount to your costs, especially if linking to your main home’s utilities isn’t feasible. In some cases, establishing a new connection can run into the thousands and will need to be assessed by a professional engineer.

b.     Existing Plumbing Integration: While many ADUs can integrate with the existing plumbing of the primary residence, this may not always be the best route, particularly if you intend to rent out the unit.

c.     Separate Meters: For rental purposes, it might be wise to install separate meters for gas, electricity, and water. This allows for easier billing and can make the unit more autonomous, which could be appealing to potential renters and add value to your property.

4.      Landscaping and Exterior Work: When budgeting for your ADU, it's essential to remember that the exterior elements are just as important as the interior. While most construction cost estimates focus on the building itself, they often do not account for landscaping or yard work. Here are some key points to keep in mind:

a.     Landscaping Costs: Be aware that the quoted price per square foot for your ADU typically excludes landscaping. However, the construction process can significantly alter your existing yard, potentially necessitating additional work.

b.     Construction Impact: The yard may be subject to trenching and other disruptions. Construction machinery and material storage will likely affect your current landscaping, and you may need to repair or reconfigure outdoor spaces once the ADU is completed.

c.     Budgeting for Outdoor Spaces: It is wise to allocate a separate budget for the design and restoration of the outdoor areas surrounding your ADU. This includes not only the aesthetic aspects but also the practical repairs from any impact due to construction.

5.      Contingency Fund: It’s recommended to allocate at least 10-20% of your total project budget to this fund. For example, if your ADU project is estimated to cost $100,000, setting aside $10,000 to $20,000 for unforeseen expenses would be a wise choice.

a.     Flexibility for Upgrades: As construction progresses, you may decide to upgrade certain materials or finishes. Having a contingency fund allows you the flexibility to make these enhancements without financial strain.

b.     Covering Unforeseen Requirements: Construction can be full of surprises – from hitting a rock bed during excavation to discovering outdated wiring that needs replacing. These unforeseen requirements can quickly escalate costs, and your contingency fund becomes essential in managing these additional expenses without derailing your project.

 Understanding Timelines: Patience is key when building an ADU. It’s a process that takes time, often more than you might expect:


1.      Design and Planning: The design and planning stage of building an ADU is a critical phase that requires a meticulous approach and can often be time-consuming. Here are strategies to ensure efficiency and accuracy during this phase:

a.     Work With Integrated Teams: Collaborating with a contractor who provides both a designer and an architect under one roof can be advantageous. This integrated approach ensures that all team members are on the same page from the outset, leading to a more cohesive plan.

b.     Early Selection of Finishes: Choosing finishes during the planning and blueprint creation phase is more than just a matter of taste—it’s a strategic move. Deciding on fixtures, finishes, and equipment (FF&E) early on can influence the overall design and might affect structural decisions or inspection criteria.

c.     Impact on Inspections: Be aware that some finishes you select could impact inspection approvals. For instance, certain materials might require specific installation methods or additional safety features. Your design team should be aware of these details to ensure that all aspects of the design comply with local codes.

d.     Finalized FF&E: Having a finalized list of fixtures, furniture, and equipment at the time of plan submission is not just about aesthetics; it solidifies your budget and helps prevent last-minute changes that could delay your project. This clarity can also provide peace of mind, knowing that every component has been accounted for and there are no loose ends.

2.     Permitting: When it comes to obtaining permits for your ADU, the time frame can vary widely depending on your specific location. Here's what you should generally expect during the permit phase:

a.     Initial Review Period: Typically, the first round of reviews for your ADU permits will take about 14 business days following a week dedicated to plan checks. This is a standard initial period where the city or governing body will assess your submitted plans for any issues or discrepancies.

b.     Revisions and Resubmission: If there are any revisions requested by the city, plan for an additional review time of around 10 business days. This is for the city to verify that all their feedback has been incorporated correctly into the plans.

c.     Architect's Revision Time: On top of the city's review time, allocate 1-2 weeks for your architect to make the necessary revisions. It’s essential to account for this time in your overall timeline to maintain realistic expectations.

`The Value of a Proficient Architect

Efficiency in Revisions: A knowledgeable and experienced architect is invaluable during this process. They will understand the intricacies of local building codes and can often anticipate potential issues before submission, which can save time on revisions.

Timely Processing: An architect familiar with the local permitting process can be crucial for timely processing. They can often navigate the bureaucracy more effectively and ensure that submissions are complete and compliant, reducing the likelihood of extended delays.

Expert Guidance: An expert architect can provide guidance on how to expedite the permitting process, potentially avoiding common pitfalls that cause delays. Their expertise becomes a critical asset in keeping your ADU project on schedule.

3.     Construction: Embarking on the construction of your ADU is a substantial commitment, and understanding the process is key to managing expectations. The construction phase is typically segmented into several distinct stages:

a.     Phase 1 - The Foundation and Underground Work: This initial phase involves laying the groundwork for your ADU. It includes excavation, setting the foundation, and handling all underground utilities. This sets the stage for a stable and well-integrated structure.

b.     Phase 2 - Framing and Rough-In: Once the foundation is set, the project moves into the rough-in stage. This is where the structure begins to take shape with framing, and key systems such as plumbing, electrical, and HVAC are installed in their preliminary form.

c.     Phase 3 - Layers and Layout: This phase sees the addition of insulation, drywall, and the initial layout of interior spaces. It's where the ADU starts to look more like a home, with rooms becoming clearly defined.

d.     Phase 4 - Finishes and Completion: The final phase is all about the details that transform the construction into a livable space. This includes painting, installing fixtures, and adding all the finishing touches that contribute to the ADU’s aesthetics and functionality.

4.     Inspections and Approvals: Inspections are a critical part of the construction process, ensuring that each phase of work complies with local codes and standards. To ensure a smooth process and to protect your investment, consider the following payment strategy:

a.     Staged Payments: It’s sensible to structure your payment schedule with your contractor around the successful completion and official sign-off of inspection milestones. This means you pay for each stage of work only after it has passed the necessary inspections.

b.     Advantages of This Approach: This payment strategy can offer you peace of mind by linking payments to the verified completion of work. It ensures that you are not paying out large sums upfront without tangible progress and that the work is executed to a standard that meets official requirements.

c.     Building Trust: Paying upon inspection approval also fosters a sense of trust and accountability with your contractor. It ensures that the contractor is motivated to meet the quality and safety standards required to pass inspections.

Considerations for Payment and Inspections

d.      Clear Agreements: Ensure that payment terms and conditions related to inspections are clearly laid out and agreed upon in the contract with your builder.

e.     Anticipate Delays: Be prepared for potential delays if issues arise during inspections. Although this can be frustrating, it’s an important part of maintaining the integrity and safety of your ADU.

f.      Quality Assurance: Ultimately, this method helps to assure quality. You want to be certain that you're investing in an ADU that is safe, well-built, and compliant with all regulations.

Tip: Always add buffer time to your projected timeline to account for delays.


Preparing Your Site

Before construction can begin, the site must be properly prepared:


1.      Surveying: Have your property surveyed to identify any potential issues such as property lines, easements, or grade problems.

2.      Clearing, Demolition, and Excavation: The site will need to be cleared of debris and vegetation. Excavation is necessary to lay a proper foundation. 

3.     Utilities: Ensure that all utility lines and connections are mapped and planned for. This might include water, electricity, gas, and sewer or septic systems.

4.     Access: Consider how construction equipment will access the site. This might involve temporary road construction or coordination with neighbors.

Final Thoughts

Starting your ADU project is an intricate process that requires due diligence and careful planning. BuildHers Blueprint is here to guide you every step of the way.


While this section has been quite comprehensive, it is my hope that it has equipped you with a solid understanding of the many facets involved in kicking off your ADU project. Setting proper expectations from the outset is crucial for navigating through the journey of building an ADU. From budgeting for unforeseen costs to understanding the stages of construction and the importance of aligning payments with inspections, each element plays a vital role in the overall process.


Remember, patience and preparation are your best allies in this endeavor. Armed with the right knowledge and expectations, you’re now better positioned to manage your project effectively, making informed decisions every step of the way. As you move forward, may this guide serve as a valuable resource to help bring your vision to life with confidence and clarity.


Stay tuned for our next post. Until then, happy planning!


A’mia Michele

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