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Design, Bid, Build with Housable, an ADU design and construction guide

Housable ADU Design Services

Housable provides reliable, high-quality, and cost-effective ADU design, drafting, and permit services for homeowners and professionals. As a general rule, Housable advises on the code, not the aesthetics of your project. Our team provides standard options which meet applicable codes for permitting, but we leave final interior design/style choices to you and your contractor during construction. You can find a contractor with interior design experience through the Housable Marketplace.

Housable is exclusively focused on ADU design, permitting, and construction projects. Our team has experience designing and permitting all types of ADU projects including garage conversions, interior home conversions, additions, and new detached ADU construction.

Our standard projects comply with the statewide standards for ADUs and typically:

  • Are single story units either from conversion of legal existing spaces, or new detached or attached ADUs less than 1,000 square feet
  • Are not located in coastal zones, severe or high fire hazard areas, or excessively sloped
  • Do not include porch or deck spaces exceeding 20% of the floor area of the unit
  • Do not include primary home remodels
  • Are not rush jobs

Our premium ADU projects include projects that are more complex and labor intensive such as: 

  • Multifamily ADU projects or single family projects that include an ADU and JADU
  • Projects with 2 stories or ADUs added above existing structures
  • Projects in excess 1000 square feet in floor area, 16 feet in height, 2 story projects, or projects with lofts
  • Projects requiring special review due to a hazard or special overlay zone.
  • Alternative construction methods outside of standard CBC 2019 (eg. modular and panelized units)
  • Remodeling of a primary home when in conjunction with an ADU conversion or new construction project.

Homeowner ADU Design Process

  1. Verify that you can add an ADU to your property by running a quick zoning check with our tool. Enter your property address into our search bar on the main home page at You will need to verify that you are a real human with a valid email and phone number. When you are asked to verify your account please double check your spam folder for the access code sent to you. If you have previously signed up with Housable, you just need to login, you can’t use a new email to access previous property reports generated with different credentials (this is a security measure for you). Your account will house all of your property checks. If you have more than one project with Housable you will be able to see them in the admin portal once you have logged in. 
  2. Once you’ve accessed your property report you can set design preferences and site location for your ADU. If you need help determining these we’re more than happy to help you decide what works best for your site, but we need some basic information to start. Fill out this information as best you can and don’t worry,  you can change this later during the design process. 
  3. Set a 15-30 minute consultation with our team where we can answer any questions you might have about getting started, or specific design related questions. It’s important to provide as many notes as possible for our team in your project bucket so that we can research your project and provide information to you during the consultation. All of our initial consultations take place remotely via Zoom. You will need to download and install the Zoom app on either your computer, tablet, or smartphone. You can also call into the Zoom meeting using the number and code provided so don’t worry if you don’t have a webcam. 
  4. Once our team has met with you regarding your project we can prepare a quote for your project. This doesn’t take much time but the quote is set to expire so you will need to either accept the quote or ask for a new one if it has expired. Once you’ve received your quote you can select a payment plan. You can either pay in installments based on design progress or you can work with our team to get a bid from a general contractor builder and pay for the design work once construction is completed (requires a design bid build contract).
  5. Now that you’ve settled on what you’d like to build, created a site plan, and determined the best method of payment, you can get started with our design team to create, modify, or permit your plans. In order for us to create the blueprints necessary for your building permit we need your help gathering some information from the property such as the location of structures, utilities, and trees. Follow these steps for creating an ADU site plan:
    1. Verify All Dimensions and Distances Marked In Orange: We need to know the location of existing buildings on the property, use a tape measure to take the dimensions of buildings and distance between them to the nearest inch. If you’re not comfortable with this you can hire a builder to help you. This shouldn’t take more than a few hours of their time so it won’t add too much additional cost. 
    2. Label All Surfaces and Structures: Once you’ve sketched out the location and dimensions of structures on the property, you’ll need to indicate what the structures are (eg. wooden decks, pavers, shed, retaining walls, concrete driveway/walkway/patio). 
    3. Indicate Slope Using Arrows Pointing Downhill: This doesn't need to be exact, just show the general direction of the slope(s). Use multiple arrows if necessary. 
    4. Mark All Trees Within 10 feet of the Proposed ADU Location: Measure and mark the circumference of tree trunks and distances from landmarks such as structures, property lines, etc. 
    5. Mark Existing Utilities On The Site Plan: Generally utilities are easy to access and see where they connect with your home. Underground services typically run from the street to the house where the meters are located. This may be more complex if your property is on a corner or an alley.  Upload the site plan to your Housable ADU Project Bucket and we’ll use this to verify setbacks and other requirements for your project. You can read here about finding your utilities.
  6. Now it’s time to design your ADU! We can either work with a design that you provide to draft and permit for you, we can customize an existing Housable library design, or we can create something custom for you. The design process will include a certain amount of back and forth as we work with you to perfect your ADU design. We use a comment and markup tool so that we can track what changes you request and our response to them. You or your contractor will have the opportunity to 'View & Markup' your design so don’t worry if you’re leaving this aspect up to your builder, they will also be able to use this tool. When adjusting your ADU design (see animated GIF below) using our plans markup tool:
    1. Use arrows and highlighted text to show desired changes to your plans
    2. Indicate removal of an element of the drawings
    3. Pose a question that you have about the plans
    4. Indicate an inaccuracy in the plans

    Marking up your ADU permit set with comments, animated gif guide
  7. Once we’ve gotten your feedback on the design, we can start the drafting process. The permit set we provide to you will include everything required by your municipality to permit your ADU including a cover sheet, a site plan and vicinity map, architectural plans including floor plans, sections, elevations, construction specs and assemblies, architectural schedules, mechanical, electrical, plumbing plans, certificate of title 24 energy compliance, and structural plans and details. The drafting process takes several weeks to a few months. 

    ADU Permit Set Drafting Phases:
    1. Phase 1: Project setup and preliminary site plan sheet.
    2. Phase 2: Floor plan, elevations, and general architectural sheets.
    3. Phase 3: Mechanical, electrical, plumbing and architectural spec sheets.
    4. Phase 4: Project review, site calculations, general notes.
    5. Phase 5: Structural, framing, foundation detail sheets.
    6. Final Plan Submittal Preparation: Finalization of plans and preparation for submission to third party title 24 certification and local planning & building departments.
  8. Now that you have a completed permit set you can start looking for a builder if you haven’t already. Housable offers all of our customers access to the ADU marketplace and we can help you source builders, manage bids, and track the progress of your project. Read more here about using the marketplace. 
  9. Once you have selected a contractor they can pull the permit for your ADU or we can help expedite that for you as owner builder. Your municipality or contractor may have comments regarding your plans, we can make adjustments as necessary which is included in the quote we provided to you, however any design changes not related to compliance will require an additional fee. If you request design changes during permitting, this will require additional fees and may trigger updates to Title 24 and other compliance documents. If custom engineering or details are required by the planning office, we can provide engineer stamps and calculations for reasonable additional fees. 
  10. With blueprints and permits completed, your builder can get started on your ADU project. You can read more here about what to expect during the construction of your ADU

Get Started with Your ADU Project