FAQs about Building an ADU2024-04-01T06:42:20-04:00


Answers To Common Questions About Building An ADU

Explore what ADUs are, delve into their construction costs, & gain insights into building an ADU. Our comprehensive FAQs page answers common questions.

What is the process to get an ADU built?2024-03-27T13:39:49-04:00

Initially, the process may seem daunting, but there’s no need to feel overwhelmed!

Your actual involvement throughout the project is minimal. You can think of your involvement as a three-step process once you have decided to build an ADU.

The ADU House Plans contain all the necessary information for the contractor to kickstart the building process. We have meticulously crafted our ADU designs to provide comprehensive guidance. With our detailed drawings, you or your contractor should not require any additional design assistance once you receive them.

STEP 1: Assess Your Lot To Determine If You Can Build And How Much

  • Assess your available space for an ADU by considering legal boundaries, zoning regulations, topography, nearby structures, and potential encroachments such as easements on your lot.
  • Understanding this information will help you determine the optimal location for your ADU.
  • Much of this information is available in your official lot survey, including your property’s zoning district. If you don’t have an official survey, search for the zoning map of your jurisdiction using the terms [“City of (your city name)” and “zoning map”]. Once you determine your residential code, search your local zoning ordinance using [“City of (your city name)” and “zoning ordinance”]. This will help you understand applicable development regulations, including permissible location and maximum size for your ADU.
  • You can also choose to have any of these tasks completed by us or your general contractor!

STEP 2: Select an ADU design that you love

Consider the size you want, bedrooms, bathrooms, if it fits within your buildable area, design and aesthetics

Browse our catalog for pre-designed ADUS.

STEP 3: Reach out to General Contractors and Hire One

  • First, reach out to multiple general contractors and present your desired ADU design and project objectives. Consulting with several contractors is vital as pricing may vary significantly among them.
  • Shortlist your options to about three contractors and request cost estimates. Consider factors such as experience, pricing, timeline, communication, and the workload of their team.
  • For further guidance on finding a general contractor, refer to the FAQs section.
  • Select a contractor when you’re ready to commence the project. Securing a contractor early on is advantageous due to fluctuating material costs, labor availability, and high demand. Your GC not only transforms the drawings into a physical building but also serves as the ADU project manager throughout. 

Once you’ve hired a contractor, they will manage the remaining steps. However, we’ve listed them here to help you understand the build process.

Why Should I Build an ADU?2024-03-27T14:00:52-04:00

Discussing the financial logic behind building an accessory dwelling unit (ADU) is straightforward; it’s an investment.

When you opt to construct an ADU, you’re not just adding space to your property, but significantly increasing its market value. Prospective buyers value the versatility it offers – whether as extra room for family or a potential source of rental income. An ADU can function as a guesthouse, home office, or creative studio, providing a separate haven for contemplation and creation while maintaining the main house’s order.

However, beyond the practical considerations, what truly stands out is the Joy of Creation. Building is a primal act of shaping one’s environment. Upon completion, you can proudly step back and declare, “I did this.” Your ADU will resonate with stories, becoming a lasting legacy for generations to come.


It must be acknowledged that challenges may arise, but these challenges come with an expiration date. Building involves navigating through permits, unforeseen plumbing issues, and budget constraints – all part of the process. The key is to view these challenges as a year-long puzzle; once solved, you’ll reflect with a smile.

So, embrace the blueprint and embark on this adventure. The challenges are transient storms; the satisfaction of creating something enduring is everlasting.


Visit our blog to read more about our musings about architecture and general recommendations.

What is an ADU?2024-03-25T11:58:54-04:00

An Accessory Dwelling Unit (ADU or DADU) is a secondary and smaller residential unit located on the same property as a single-family house.

Essentially, it serves as an additional living space coexisting with the main home. Whether attached to the primary residence or freestanding, such as a converted garage or standalone structure, ADUs are designed as independent living spaces.

image of 2 bedroom_2 bathroom_ADU

They serve various purposes, including accommodating aging parents, providing housing for caregivers, hosting guests, creating a dedicated work-from-home office space, generating additional rental income, or offering a private living arrangement for family members.

ADUs are also known by other terms such as In-Law Suite, Mother-in-law suite, Granny flat, Backyard guest house, Backyard cottage, and Carriage house.

Visit our blog to read why you should build an ADU.

Visit our ADU Collection for comprehensive ADU plans.

Do you also build the ADU? Do you offer turnkey solutions?2024-03-27T13:59:14-04:00

After extensive deliberation on this matter during the inception of our firm, we decided to steer away from offering both design and build services under one roof in order to provide the best service to our clients and with the most integrity.

Opting for a design-build company that promises to handle every aspect of your project may seem convenient at first glance, but the reality often falls short of expectations. Upon closer scrutiny, this approach may not save time or costs, and it can even compromise the quality of construction.

One significant issue that arises with design-build models is the challenge of budgeting. The seamless integration of design and construction phases can exacerbate budgetary concerns. This integration creates a potential conflict of interest since the same entity is responsible for both designing and building. In such cases, the design-build company might prioritize cost-cutting measures during construction, potentially sacrificing the integrity of the overall design.

Moreover, the design-build approach tends to limit competitive bidding opportunities. Unlike traditional project delivery methods where multiple contractors can bid on construction tasks, design-build firms often have a set group of preferred subcontractors. This lack of diverse bids can lead to less competitive pricing and potentially inflated construction costs.

Furthermore, the lump-sum contracts commonly offered by design-build firms obscure the breakdown of costs between design and construction services. While this consolidated approach simplifies budget management, it also diminishes transparency regarding where exactly the client’s funds are allocated. This opacity can leave clients unsure of how their budget is being utilized and whether they are receiving optimal value for their investment.

Visit the 7 Reasons Why You Should Go with a GC for your ADU (Instead of Design-Build) for more detailed information.

We also recommend understanding the 3 main ways of how to build your ADU here, before you make a decision to go with a design-build company.

Can I customize my ADU?2024-03-27T12:55:41-04:00

Certainly. You have the flexibility to choose between two exterior color options: Norwegian Wood (gray vertical siding with wood-colored accent siding) or Shady Gray (white vertical siding and gray accents). We can also work with you for custom exterior colors to match your principal residence. Additionally, you can customize interior finishes colors and light fixtures. Note that this does require adjustments in the drawings which will incur a flat fee of $175 for color changes.

While you can change appliances, it is your responsibility to ensure their compatibility with designated spaces.

Modifications to the plan or design are also allowed for a fee charged by the hour. Note that any changes to the Fast Track pre-reviewed designs will disqualify them from the expedited permit review process.

I am a GC. Can I be recommended to your clients and customers?2024-03-27T14:01:52-04:00

Certainly! We frequently receive inquiries from customers seeking contractor recommendations, and we are continually looking for high-quality, reputable builders to partner with or recommend. Please reach out via email to initiate further discussion.

How long does it take to build an ADU?2024-03-27T13:39:27-04:00

Our designs prioritize efficient structures, notably the Ascension Home ADU, where the exterior envelope and foundation can be installed in one week. As designers, we’ve done our best to expedite the construction process, however, the overall time frame for your ADU to be move-in ready ranges from five to nine months due to a number of factors. 

image of sustainable ADU foundation_prefabricated steel above grade foundation

Permitting typically takes one to two months. Material lead times range from several weeks to a couple of months. The actual build phase, approximately three to six months, depends on your contractor, their teams, and their project workload. Finally, scheduling and obtaining final city inspections during construction can take several days to several weeks at each phase.

Image by freepik

Recognizing that construction timelines in the United States are often prolonged due to factors like market volatility, an aging construction labor market, and a lagging regulatory environment, we aim to address this issue by designing prefabricated and modular homes this year.

Are any of the ADUs accessible?2024-03-25T09:57:47-04:00


We promote universal accessibility in all building design. Although our plans are not explicitly ADA-compliant, we offer two designs already on grade, featuring 36” doors in key rooms such as bedrooms and all are designed with minimum 40 inch wide hallways. Moreover, all designs can be adapted to meet accessibility needs, and we can explore specific plans for wheelchair accessibility.

I want to build an ADU. What do I need to know?2024-03-31T07:54:51-04:00

Constructing an ADU is a genuine construction project, akin to building any home. However, our designs and detailed plans streamline the process. First, it is imperative to align your ADU with local zoning regulations regarding size and location. Secondly, you need to engage a reputable General Contractor.

The drawings serve as one half of the project, with the other half is the physical implementation of the drawings which is overseen by your General Contractor who acts as the project manager and interfaces with the building department on your behalf.

See How to Get Your ADU Built for more detailed steps.

I do not live in Raleigh or North Carolina. Could I still buy the design and use the construction documents?2024-03-25T10:05:14-04:00

Certainly! Atmos Arc designs and plans adhere to International Residential Code 2015 standards, which is adopted by most municipalities as a baseline for their codes. While your construction plans may be permit-ready at the time of purchase, it’s advisable to engage a local building professional (engineer, architect, builder) to verify compliance or make necessary modifications based on specific jurisdiction requirements. If you’re outside of North Carolina, your local jurisdiction might require an engineer to review and stamp your drawings for your lot.

How do I know your ADU designs will give me a quality build?2024-03-25T11:41:17-04:00

Ensuring a quality-built ADU extends beyond the drawings alone, however, the drawings are one of the most critical pieces. Overall, achieving good construction hinges on various factors. A reputable and experienced General Contractor, reliable subcontractors, and quality suppliers play pivotal roles as well. It’s imperative to prioritize quality materials and steer clear of sources like Amazon. Architectural drawings should also be adhered to.

Other factors such as: home maintenance, proper storage of materials during construction, prompt home repairs when needed. Effective moisture protection is a must –the drawings incorporate sound strategies for this purpose. Proper site grading away from the home, and meticulous attention to quality foundation construction are also key elements in ensuring the successful realization of a well-built ADU.

So, while the construction drawings are imperative for any construction project, having a durable home for generations depends on many other things working together.


What is the difference between a Builder and an Architect?2024-03-26T09:26:09-04:00
  • Design Expertise: Architects are trained to create functional, aesthetically-pleasing, and innovative designs. They excel in understanding human needs and translating them into well-designed homes. In contrast, builders often follow a more standardized approach that may lack personalization.

  • Innovative Ideas: Architects bring a fresh perspective to your project. They stay updated on the latest trends, materials, and construction techniques, offering innovative ideas that can enhance the functionality and aesthetics of your home.
  • Problem Solving: Architects are skilled problem solvers. They can address challenges related to the site, local building codes, and your specific requirements. Their expertise can result in creative solutions that make the most of your property and budget.
  • Cost-Efficiency: While architects may have fees, their involvement can lead to cost savings in the long run. A well-designed home can optimize space, energy efficiency, and materials, potentially reducing construction and operational costs over time.
  • Legal Compliance: Architects are familiar with local building codes and regulations, ensuring that your project complies with all legal requirements. This can save you time and potential legal issues down the road.

  • Value Enhancement: A well-designed and architecturally significant home can potentially increase its resale value. Buyers often appreciate the attention to detail and thoughtful design elements that architects bring to a project.
  • Long-Term Vision: Architects consider the long-term implications of design decisions. They can help future-proof your home by incorporating features that allow for adaptation to changing needs and technologies.

So, while a home builder can indeed excel in executing the construction phase, architects bring a distinct set of skills and contributions to the table. Architects are involved in shaping the vision, conducting thorough planning, researching building codes, providing technical construction expertise, and ensuring the overall success of the project. In contrast to the home builder, the architect collaborates with a general contractor to oversee the construction of a custom home designed by the architect.  This partnership between architects and general contractors is essential for creating a home that is not only well-designed but also well-constructed and provides a valuable alternative to home builders.

Get an understanding of our overall design philosophies as architects or visit our blog for tips and design musings.

What comes with a purchase? What is the final product?2024-03-25T10:38:22-04:00

When you acquire a license for our ADU designs, you’ll receive digital House Plans, also known as Construction Documents.

Construction Documents encompass the written and graphic materials crafted by an architect to articulate and convey the design, structure, and physical attributes of a building project. These documents are essential for obtaining building permits and serve as the required documentation for managing the construction contract between the owner and the General Contractor. Our ADU House Plans comprise a comprehensive construction document set, ready for your contractor to execute into a physical building! 

image of ADU construction drawings

Constructing a building is a complex process that requires the coordination of numerous trades and components. While it can be a meticulous service, having the right set of construction documents makes the building process not only rewarding but also somewhat easier. Additionally, unlike most house plans that lack interior design details, we have gone above and beyond to provide thoroughly-detailed, ready-to-build documentation. This requires no further involvement on our part and minimal effort on your end!

Learn more about what’s included in the final product here under “What you get with your purchase.”

Can I build an ADU on my property? How do I know what size?2024-03-31T07:57:24-04:00

If you reside within Raleigh, you can consult the Unified Development Ordinance (UDO) relevant to your zoning code.

For those outside Raleigh or North Carolina, simply search “[your city] zoning ordinance” and “[your city] zoning map” to locate specific information for your area.

Relevant details such as your zoning district (“R-4”, “R-10”, etc), lot topography, nearby structures, and potential encroachments such as easements on your property—all of which can influence the location and size of your ADU—are typically included in your official lot survey. Pairing this information with your city’s zoning ordinance allows you to identify applicable development regulations based on your zoning district.

If this sounds too confusing, you can have your GC complete this task or you can hire us to do a remote site consultation.

What are the benefits of the Fast Track program?2024-03-25T11:04:03-04:00

As outlined in “What does Fast Track mean,” you can expedite the permit review process by up to two weeks. However, the substantial advantage lies in bypassing the conventional building design process, potentially saving three to six months and avoiding design fees ranging from $30k to $50k.

Visit our ADU Collections page to find fast-tracked ADU designs and pre-designed ADU plans.

What does Fast Track mean?2024-03-25T11:10:08-04:00

Designs featured in the Raleigh ADU Fast Track Gallery have undergone pre-review by the City of Raleigh for Building Code compliance. Choosing a pre-reviewed design can expedite your permit review by up to two weeks. However, it’s important to note that, before proceeding with ADU construction, you must apply for and obtain all necessary permits, including Building Code permits. Additionally, your lot must undergo a zoning review by the City’s Planning Department to assess development regulations specific to your site. Finally a site plan is mandatory for all ADU permit applications.

The substantial advantage of our Fast Track ADU designs really lies in bypassing the conventional building design process, potentially saving three to six months and avoiding design fees ranging from $30k to $50k.

Visit our ADU Collections page for a selection of pre-designed ADU plans.

What is the best way to reduce costs when building my ADU?2024-03-25T11:19:21-04:00

The most effective cost-cutting strategy for a small home involves designing efficient structures (foundation, exterior walls, roof), reducing construction time, choosing reputable material manufacturers that warranty their materials.

Given the home’s size, opting for cheap finishes will not significantly impact the overall price, but can actually impair the long-term value.

Where you should expect to see savings in our ADUs over the average ADU build:

  • Soft Fees: Traditional design fees, typically 10% to 25% of total construction costs, are avoided by using pre-designed house plans. This not only saves four to six months of design time but also results in savings of $30,000 to $50,000 in design fees.
  • Manufactured Foundation System for some of our ADU designs: This system requires minimal excavation (moderate site grading for drainage and minimal excavation for utilities only), saving several weeks of construction time.
  • An efficient structural design leads to quicker construction by facilitating easy installation and simplified material sourcing.
  • Long-term Energy Savings: Achieved through a tight building envelope and the use of energy-star appliances.
  • No Large Machinery Needed: Design considerations for potential narrow or limited access to the backyard mean that all materials can be placed and installed by hand or using small machines such as jackhammers.

image = hands finishing concrete footing

Longevity & Durability: Our homes are designed for lasting durability, featuring high-quality finishes like fiberglass windows, standing seam roofs, and engineered wood floors. This design approach contrasts with generic builder homes that may require frequent maintenance and premature finish replacements.

How much does it cost to build an ADU?2024-03-31T07:58:23-04:00

While we have put forth every effort to design an affordable small home, the final pricing is determined by your General Contractor based on various factors such as material price, construction labor, site conditions, utility connections, inflation, and GC factors like their current project load, GC profit and overhead, and market volatility.

As of January 2024, the estimated cost to build an ADU in Raleigh, North Carolina ranges from $240 to $350 per square foot. In other jurisdictions, construction costs can escalate to $500 per square foot. Considering the construction escalation due to market volatility, we strongly advise bringing on a general contractor early for current construction estimates.

Each contractor and subcontractor may price a project differently. We recommend obtaining estimates from at least three different contractors for comparison. Keep in mind that ADUs typically cost more per square foot than regular-sized homes due to economies of scale. With smaller square footage, the same amount of labor needs to be distributed over a smaller area, making small homes comparatively more expensive on a per-square-foot basis (but not overall).

Recently, we’ve observed a variability of 25-40% among contractors in some cases. Stressing the importance of speaking with multiple contractors cannot be overstated.

How do I find a General Contractor? Do you have any contractor recommendations?2024-03-27T12:54:30-04:00

To find a general contractor, we recommend the following steps:

  1. Look for a small home builder experienced in sustainable construction. Avoid those unfamiliar with these methods to prevent potential cost increases.
  2. Interview multiple contractors to assess communication, work style, and pricing. Costs can vary significantly.
  3. Ask important questions:
    • Can you provide references?
    • Are you licensed?
    • Will you secure all required building permits?
    • What types of insurance do you carry?
    • What is the expected project timeline? (Our projects typically take at least a month less than typical constructions.)
    • Do you provide a warranty on your build?
    • What drawings do you need for a cost estimate?
  4. Initially, seek recommendations from friends or family. If unavailable, check local sources like your local Chamber, HomeAdviser, Angie’s List, and Houzz.
  5. After identifying a few contractors you prefer, we can provide you with a selection of key drawings from the construction document set to facilitate pricing. Following the contractor selection, we remain accessible for a brief call to address any construction-related details.



For serious inquiries, we collaborate with a select few contractors who may have a waitlist for new projects. Feel free to reach out to us for more information.


Do you have a model home? Can I see an ADU in person?2024-03-27T12:53:35-04:00

The ADUs that are constructed serve as private residences, and as such, we cannot offer model homes for tours. Our primary focus is on designing for clients and producing detailed construction drawings that General Contractors use for execution and construction.

While we don’t provide physical tours, we can offer a condensed sample from our Construction Document set. This glimpse showcases the detail and depth present in our design and construction drawings. We hope this provides you with valuable insights to make an informed decision about your ADU project.

You can also reach out to us for an interior design palette for each ADU design and you can view our ADU Collection page under “What You Get with Your Purchase for a better understanding of the final product.”

Looking to build an ADU?

Check out our catalog for ADU Designs Ready to be Built!

Choose from our 2 bedroom, 1 bedroom, and even 2 bath 800 SF ADU designs.

Go to Top