As the demand for accessory dwelling units (ADUs) continues to rise, homeowners are exploring various construction options to meet their needs and budgets. One increasingly popular choice is the shell ADU, also known as white box construction or tape and texture. This type of ADU offers a partially completed structure, allowing homeowners to save on initial costs and customize the interior over time.
In this comprehensive guide, we will delve into the fundamentals of shell ADUs, the benefits they offer, the construction process, as well as provide insights on selecting the right contractor and evaluating whether a partially finished ADU is the right choice for you.
What is a Shell ADU?
A shell ADU, often referred to as “white box construction” in commercial real estate, is a type of accessory dwelling unit that is partially completed. The term “shell” implies that the ADU includes the essential structural components: foundation, framing, roofing, siding. It also includes interior work like electrical, plumbing, HVAC and insulation, all the way until drywall. This is why we at SnapADU call this option “tape and texture,” as in drywall finish. However, it leaves out the interior finishes like flooring, doors, cabinetry, and fixtures. This type of construction provides a blank slate for homeowners to customize the interior according to their preferences and budget.
The concept of a shell ADU differs significantly from a fully finished ADU, which is move-in ready upon completion. Fully finished turnkey ADUs include all interior finishes and fixtures, requiring no additional work from the homeowner post-construction.
What does a shell ADU build include?
A shell ADU project typically includes:
- Design & permitting
- Utilities & sitework
- Foundation & framing
- Roofing & exterior finishes
- Electrical & plumbing rough-in
- Insulation & drywall
A shell ADU project typically does not include:
- Exterior lighting & flatwork landings
- Interior doors & hardware
- Flooring
- Paint, trim, & shelving
- Light & plumbing fixtures
- Cabinets, countertops & appliances
For more details on what’s included in our shell builds, see our Tape and Texture home specifications.
Who Picks Shell ADUs? When Might It Be Right for Me?
DIY Types
For those who enjoy hands-on projects and have some experience in construction, finishing an ADU can be an exciting and rewarding endeavor. Homeowners who are budget-conscious and willing to invest their weekends in working on the ADU will find shell ADUs appealing. This approach allows for significant cost savings, as you will be assuming responsibility for ensuring the quality and durability of all the finish work. You could also choose to subcontract some or all of the labor, self-managing the rest of the project.
Investors with Existing Contractors
Investors who already have a reliable team of subcontractors but lack the expertise in ADU regulations, design, and permitting can benefit from choosing a shell ADU. By handling the initial construction and allowing their team to finish the interiors, investors can streamline the project while ensuring compliance with local laws.
Benefits of Choosing a Shell ADU
Cost Savings from Self-Managing
The biggest advantage of a shell ADU is the potential for cost savings. By opting for a partially finished unit, homeowners can save on the upfront construction costs associated with interior finishes, opting to complete them over time. This can be particularly beneficial for those who have a tight budget or prefer to spread out their expenses over time. However, it’s important to note that to obtain occupancy for the ADU, certain steps must be completed. This includes installing cabinetry, appliances, fixtures, and ensuring all electrical and plumbing work meets code requirements.
Customization Flexibility
Shell ADUs offer flexibility in customization. Homeowners have the freedom to choose their finishes, fixtures, and appliances, ensuring that the final product aligns perfectly with their tastes and needs. If you have a very specific vision in mind, completing the interior yourself could be a great option.
The Construction Process of Shell ADUs
Feasibility Studies and Design
The planning and design phase is crucial and can be challenging without the right expertise. This is why many people hire reputable ADU companies like SnapADU. The benefits of a design/build firm are numerous, including accountability, streamlined communication, cohesive design, and efficient project management.
A thorough site assessment and feasibility study are essential first steps. These studies evaluate the property’s suitability for an ADU and identify potential challenges, ensuring a smooth construction process.
Permitting and Regulatory Compliance
Navigating the permitting process and ensuring compliance with local ADU regulations is highly complex. We encounter novel challenges weekly, and we’ve been building ADUs for years. Reputable ADU companies have the experience and knowledge to handle regulatory tasks efficiently, advocating when needed, and saving homeowners time and stress.
Building the Shell
Building the shell of an ADU involves several key phases that provide the basic structure and essential elements, leaving the interior finishes for the homeowner to complete. The process begins with mobilization, where the ADU’s footprint is staked out on the property, and initial site work is carried out to prepare a stable base for construction. This includes removing any obstacles and ensuring the site is ready for the foundation.
Next, trenching and foundation work commence, involving digging trenches for utilities and laying the concrete foundation. Following this, the framing stage constructs the skeleton of the ADU, outlining the basic shape and structure. Once the framing is complete, rough mechanical, electrical, and plumbing (MEP) systems are integrated into the structure.
Exterior finishes, such as roofing, stucco or siding, windows, and exterior doors, are then installed to make the ADU “water tight,” protecting the interior from the elements. Finally, insulation and drywall are added, providing the basic interior walls and insulation needed to maintain a comfortable indoor environment.
For a detailed overview of the ADU building process, visit our full page on building an ADU.
Financial Considerations for Shell ADUs
The cost of constructing a Shell ADU includes all the essential structural elements but excludes interior finishes. This can result in significant upfront savings compared to a fully finished ADU.
Choosing the tape and texture option will reduce the overall ADU project cost by $40K-$90K+ (including both materials and labor) depending on the size of the ADU plan selected.
While the initial costs for a Shell ADU are lower, homeowners should budget for the additional labor and material expenses required to complete the interior finishes.
Lessons Learned from Shell ADU Builds
From establishing a clear scope to ensuring precise plans, there are many lessons to learn from previous Shell ADU projects.
Clearly Define Scope
Clearly defining who is responsible for each phase of the project, where the contractor’s responsibilities start and stop, and what tasks the homeowner will complete is vital. This clarity helps prevent disputes and ensures that all parties are aware of their obligations. It’s important to note that if the homeowner is completing some of the work, the warranty might only cover the parts of the build that the contractor completed.
Regular updates and open lines of communication with your contractor can help identify and resolve issues early, minimizing delays and cost overruns. Using a project management system can facilitate this communication and keep track of all the moving parts of your ADU build.
Choosing the Right Contractor
This cannot be overstated. Working with a contractor who has experience in ADU construction and a proven track record can make a significant difference in the outcome of your project. They will be familiar with local regulations and best practices, ensuring that your Shell ADU is built to code and meets your expectations.
Selecting the right contractor is crucial for the success of your Shell ADU project. Look for contractors with experience in ADU construction, positive reviews, and a solid portfolio. For more tips, check out our guide on how to pick an ADU company and how to compare bids.
Completed Shell Projects
Explore our successful shell ADU projects to see how other homeowners have benefited from this approach. These case studies provide valuable insights into the process and outcomes of Shell ADU construction.
Deciding if a DIY ADU is Right for You
Consider your budget, DIY capabilities, and timeline when deciding if a shell ADU is the right choice for you. Evaluate how much work you are willing and able to do yourself versus hiring professionals. Assess the overall value of taking on a DIY project, including the potential cost savings and the satisfaction of personal involvement, against the time commitment and possible stress it might entail. Additionally, think about the quality and longevity of the finishes you can achieve on your own compared to those completed by experienced professionals, and how this might affect the long-term value and functionality of your ADU.
It’s also important to consider the unknowns of managing the project yourself. Consulting with professionals who have extensive experience in ADU construction can help you avoid common pitfalls and ensure that your project is completed smoothly and efficiently. Their insights can be invaluable in navigating the complexities of ADU regulations, design, and construction, ultimately saving you time, money, and frustration.
Can I build my own ADU in California?
With the right expertise, you can build your own ADU. Should you choose to build your ADU on your own, you have the option of working completely alone, or purchasing from a company that offers DIY ADU packages for those especially construction-savvy homeowners. However, opting to build your unit entirely on your own will require incredible organization as you self-manage dozens of subcontractors and vendors that will provide you with the necessary materials to complete the job.
It is worth noting that building an ADU on your own can be challenging, as there is a greater risk of making a costly mistake. Most projects face regulatory hurdles as well, and much of what we do as a trusted ADU company is advocate for our clients. Many general contractors have processes in place that have been refined and perfected over various projects throughout the years. Without this insider knowledge, you may hit more roadblocks than if you opted for an alternative build process, which has the potential to cost you more money and to prolong your project’s timeline.
Ready to weigh options? Contact SnapADU for a comprehensive consultation. We can help you determine the best approach for your property and guide you through the process of creating your ideal ADU.
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