Technical Design E-Guide for ADUs

Technical Design E-Guide for Accessory Dwelling Units (ADUs)


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This technical design guide is for architects, builders and DIYers who are creating accessory dwelling units (ADUs). It provides comprehensive action-oriented guidance for building assembly detailing, product specifications, HVAC and hot water systems, and code compliance strategies. Homeowners can also benefit from the guide to better advocate for their goals and enhance interactions within the team.

⭐️ Are you an E-Guide purchaser wondering where to find the latest version? Log in and then head over to the private ADU E-Guide Buyers' Group (only visible to buyers who are logged in).

Browse a teaser of the ADU E-Guide:
Cover of ADU E-Guide

The guide was developed by the architects and engineers at Beyond Efficiency (the creators of BuildingGenius), who believe that good housing should be attainable for everyone. The guide provides a common-sense approach to technical ADU design that is grounded in passive design principles, all-electric systems, and procurable products. It balances the ideals of efficiency and earth-friendly strategies with cost and constructibility.

What if my project isn't a new ADU?

We think you'll still find a lot of value in the technical design guide. While the California Title 24 energy code requirements referenced in the E-Guide are specific to new ADUs in a specific climate zone, the vast majority of content is relevant to any small-scale building, and many of the underlying strategies are also applicable to renovations or additions. See FAQs section for development plans for other climate zones and topic themes.

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The E-Guide recommends "smart practices" that work in the majority of California's climate zones, but where recommendations vary by region, those differences are highlighted throughout the guide. 

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All BuildingGenius members have access to themed discussion groups on challenging technical topics related to the content in the ADU E-Guide. Here you can interact with other professionals, including the Beyond Efficiency team, to dig into th­e specifics of your project and help you make the right decisions with confidence.

Explore the BuildingGenius ADU

This schematic shows key technical design topics of an ADU. The E-Guide addresses each component in depth including "smart practices", code requirements, high quality details, HVAC diagrams, and more to support and accelerate the decisions on your ADU projects.

ADU E-Guide navigation home

The strategies and details outlined in the e-guide are complemented by product listings, educational resources, and discussion forums in BuildingGenius. Together, they provide a dynamic and holistic solution that will help advance your ADU design in a fraction of the time.

Have other questions about the E-Guide?

Read the FAQs to learn more.

How will the E-Guide help me?

Limited time and competing priorities shouldn't force you to sacrifice optimal decisions. As building industry professionals ourselves, we know how much time it can take to navigate complex and confusing codes, research products and best practices, and design good details. The guide will give you confidence to make better decisions and make it easier to create efficient, comfortable, healthy, and durable ADUs. 

Can I buy the E-Guide if I'm a homeowner?

Yes. While the E-Guide is currently focused on addressing the challenges of design and building professionals, it can also help homeowners better advocate for their goals (homeowners have said they feel empowered by knowledge learned from the guide). Also note that we allow and encourage the E-Guide PDF to be shared with others on the immediate project team to help close knowledge gaps and enhance interactions within the team. 

How does the guide compare to individualized consulting?

While nothing can fully replace custom consulting, our goal with the E-Guide is to get you 80% of the way there at a fraction of the cost. 

Clients typically come to us with a variation of the same few challenges when it comes to designing ADUs such as fitting HVAC equipment into tight spaces, creating an efficient envelope while keeping construction costs reasonable, and answering the question "does this design meet Title 24?" This E-Guide distills knowledge from experienced professionals into a practical guideline that helps address these challenges.

Note that you’ll still need to develop the building permit submittal set, including Title 24 compliance documentation specific to your project. 

Do I have to pay for updates?

We are releasing minor version updates monthly or quarterly through 2024. These will be available for free within one year of your initial purchase. These updates will clarify questions,
fix errors, link to new resources and product listings in BuildingGenius, and integrate new topics, summary charts and "Smart Practice" strategies.

For the major version updates released every three years to align with building code update cycles, payment will be required.

The current version 1 (including any of its minor updates, e.g. 1.1, 1.2 etc.) is for the 2022 Title 24 codes that are in effect from 2023 through 2025. Version 2 will cover the 2025 codes that will go into effect in 2026.

Why ADUs?

ADUs are one of the most important tools cities have to address the housing shortages in their communities. They're created on land that is already owned, and they cost a fraction to build compared to subsidized affordable housing projects in urban areas. ADUs: 

  • Increase housing supply while mitigating demand for publicly subsidized projects
  • Reduce displacement of community members 
  • Provide financial security to homeowners