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Building design and construction process – step by step

Reasonable people may disagree, but here are the sequential steps in designing and building an ADU. This is an approximation of the steps for my ADU project, anyway. This was for an ADU built in Portland, Oregon. Slab on grade, stick frame construction—pretty standard ADU construction for this area.

**Get a PDF version of this step-by-step process, and a bunch of other resources about building an ADU on

Design Process

  • Funding
  • Brainstorm with other funder/executors
  • Talk to City Planner
  • Rough sketch some ideas with executors/friends
  • Talk to neighbors
  • Integrated Design Process
  • Interview architects (test them with some small space design questions: eg. What are a couple things that you would do to make a small space feel and act bigger? tall ceilings, join living/dining room, high windows, coupling functionality
  • Find builders and subs (ideally, you want to have identified a builder, plumber, mechanical, electrical subcontractor)
  • Architect draws up schematics for consideration
  • Have meeting- talk through design goals
  • Schematic refinement
  • 3D model (use SketchUp)
  • Develop drawings for City
    • Permit process- In Portland, processing takes 10 days for new construction, then another 10 days for corrections
  • Permits
Construction Process
  • Break Ground
  • Excavation
  • Foundation
    • Concrete Forms
    • Pour Foundation Wall
    • Concrete Slab Pour
      • Gravel
      • Water Barrier
      • Rigid Foam
      • Rebar (and PEX tubing for radiant floor heating)
      • Pour Concrete for Slab
  • Utilities
    • Sewer, Electrical, Water, Gas
  • Framing
    • Balloon Framing
    • Sheathing
    • Roof
    • Stairs
    • Windows
  • Roofing
  • Weather Resistant Barrier
    • Rain Screen
  • Rough Plumbing
  • Mechanical Sytems
    • HVAC
  • Lighting and Electrical
    • Ambient
    • Task
    • Accent
    • Perimeter
  • Air Sealing
  • Insulation
    • Spray Foam, Blown-in Insulation, or Batt Insulation
  • Drywall
    • Sheetrock, Mudding, Sanding, Primer
  • Siding
  • Flooring
  • Tiling
  • Painting
  • Cabinets, Shelving
  • Finish Plumbing
  • Finish Electrical and Lighting
  • Certificate of Occupancy
  • Modifications
  • Moving In

About Kol Peterson

Kol is an ADU consultant, advocate and author of Backdoor Revolution: The Definitive Guide to ADU Development. Read more here: and learn about building your own at

7 comments on “Building design and construction process – step by step

  1. SAndeep
    December 23, 2012

    Thank you sir

  2. Muhammad.
    October 3, 2013

    This was extremely helpful. Really appreciate it.

  3. Pingback: The Second Coming of Detached ADUs in Portland | Accessory Dwellings

  4. Steve Jepson
    October 4, 2016

    Could you recomend an Eningeer in Portland, OR for a project like this? Why is Engineering not listed as one of your steps?

    • Kol Peterson
      October 8, 2016

      Steve, engineering is sometimes required, depending on the complexity of the construction. Engineering is done in conjunction with the design work prior to submission to the City for plan review. I don’t have any referrals for you.

      • Steve Jepson
        October 8, 2016

        It’s not so much the complexity of the construction that mandates engineering as it is meeitng siesmic and lateral resistance requirments for windloads. This is especially true of older structures being renovated into ADU’s since they may have never met these requirements in the first place, or the current Energy Code. Engineering and Energy Calculations, Noticicatoins to neighbors, Demolition Permits, waste disposal, Storm Runoff Plans, and more beaurocratic encumberances from the City are significant cost factors that can make or break an ADU project. Be sure you know the cost of all the time and nonsence you will be put through before you start. Perscriptive code solutions to meet the structrual and energy codes are not always the most cost effective.

  5. Yvette J Lafleur
    May 6, 2017

    Thanks so much this was helpful. Palo Alto ,California will be finally relaxing the restrictions on June 8th .This really helped I’m so Excited and freaking out a bit .My neighbor has one I love so will be talking wirh her alot.

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This entry was posted on November 9, 2011 by in Design & Build and tagged .
ADU Summit
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