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  • Just because an ADU appears to be allowed on your property, it does not guarantee approval. Reach out to the respective jurisdiction and describe the project in as much detail as possible to garner initial instruction for moving forward. Once zoning approval is acquired, permitted building plans will be released from The Urban Infill Project. 

  • Certain items / building systems can be eliminated from plans and NO additional services or square footage will be allowed by the jurisdiction. Eliminations must be noted during the zoning review process.

    • Allowable eliminations: 

      • Washer/dryer

      • Entire Kitchen or Bathroom (this makes the building qualify as a sleeping quarter)

      • Whole house gray water system (we recommend you include the infrastructure, and allow it to drain into the sewer system if the site is not designed to receive gray water. Note: new construction must include gray water from the washing machine as a minimum).

      • Non-bearing walls

  • NO change to the overall building height, roof shape, or footprint will be allowed by the jurisdictions. NO added plumbing or electrical fixtures will be allowed by the jurisdictions. Fixtures can be moved from their designated locations a matter of a few inches only. Cabinetry can be changed in the field.

  • Most openings are drawn at 6’ wide and can receive either a window or a sliding glass door. All 6’ wide openings can be reduced in size. Note: bedroom windows must provide proper egress:

  • All plans can be rotated or mirrored in any direction to accommodate the building site. Urban Infill Project will provide template drawings for site planning purposes upon request. 

  • Plans are drawn with attention to accessibility for people to age-in-place and to provide housing stock for wheelchair users. All doors are 3’ wide rough openings and kitchen and bathroom clearances align with ICC accessibility standards for@ dwelling units.   

  • All projects require Manual J/S calculations to be submitted with each project. These can be provided by licensed Mechanical Contractors.

  • All plans are drawn with wood-frame and site-built construction details. A builder can opt to change the structural envelope to SIPS panels or Mikey Block, Concrete Block, or various other systems - in these cases, submit manufacturer shop drawings or system engineering with the zoning review application. Urban Infill Project can assist in coordinating with manufacturers or engineers by providing general architectural drawings and details.

  • All finishes are variable - exterior and interior textures, colors, and finishes as described in drawings and details are suggestive and diagrammatic in nature. Homeowners shall work directly with contracted builders to make on-site selections that are in line with the owner's goals, local context, HOA’s, material costs and availability, or other factors.

  • The buildings are drawn and reviewed according to standards of the 2018 International Residential Building Codes and Local Jurisdiction Amendments. We recommend homeowners work with licensed, bonded, and experienced builders, contractors, and subcontractors who are well-versed in these codes and can assist in weighing any considerations around proposed field changes. Builders and owners are responsible for reading all notes within the drawings and are wholly responsible for building in compliance with all accepted international residential building codes and local amendments and zoning codes.

  • An ADU needs to be tied into existing site utilities, i.e. plumbing and electrical. These homes are designed to be all electric and are calculated to use 100A of power. Urban Infill Project does not specify any brands of equipment. It is recommended that a licensed electrician be utilized and all equipment purchases are verified to be in alignment with electrical load calculations. Upgrades to site utilities, and tie-ins to existing systems shall be coordinated on site and with local utility companies as needed. Licensed Builders should be capable of assisting homeowners with this in the field. The site plan submittal process requires documentation of existing site utility sizes, capacities and tie-in locations.

​General Sustainability Design Guidelines

*Please note, our preferred site planners are capable of assisting with discussing and guiding you in sustainability or energy consumption issues. They are also capable of creating a high-performance site plan, this may be an additional fee.


  1. The environmental performance of small structures such as accessory dwelling units are highly dependent on a few simple design choices that greatly improve general energy consumption and costs over the lifetime of the structure.

  2. The main environmental factors that affect energy and utility bills in southern arizona are: 
    a. Sunlight & shade (specifically winter sun access provides heat and summer shade reduces heat)
    b. On-site rainwater harvesting 
    c. On-site graywater used for watering landscape

  3. Cooling costs in spring, summer, and fall are minimized due to a few simple design choices:
    a. Orient the building such that the long elevations are facing north and south, and the short elevations are facing east and west.
    b. Shade the east and west elevations of the building with tall trees and/or trellises.
    c. Shade the south elevation of the building with an overhang, porch, shade sail, or other overhead shading device designed to maximize shading during the hot summer months, and to allow for direct solar access during the cold winter months.

  4. Heating costs in the winter are minimized due to a few simple design choices:
    a. Allow sunlight to enter south-facing windows by keeping overhead shading devices within 6' of the building elevation or removing shading device(s) in winter.
    b. Plant trees to southeast and southwest of structure, but not directly south, as this will prevent sunlight from heating structure in winter, and prevent solar panels from capturing maximum sunlight.

  5. Mechanical cooling and heating costs can be further diminished by choosing energy-efficient mini-splits/heat pumps, and using dual pane low-e windows on all north, west, and east facades.

  6. Site plan design is not included in the adu model building plans. site plan design, including vegetation and water management, are critical to a high-performing and low-consumption structure.

  7. Observation of the existing primary structure on the site will provide much of the information needed to plan a high- performing site design for the accessory dwelling unit, including areas of shade, vegetation, excessive heat, excessive cool, water pooling, water draining, solar exposure, and etc.

  8. If you need further assistance to draw a site plan, please contact the Urban Infill Project. an additional fee applies.

High-performance site plan resources for building sites in Southern Arizona




Drought-tolerant and native vegetation species thrive in southern arizona's heat, sun, and water conditions. resources   for native plant purchase and design can be found throughout Tucson and online, including:

a. Tucson Clean and Beautiful's Trees for Tucson Initiative

b. Desert Survivors



General ADU Info Links

General ADU
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