FAQs

Answers before you ask

Everything you need to know about building an ADU in the Columbia Gorge, from feasibility and cost to permitting and timelines. Still curious? We’re always happy to talk it through.

01 - ADU Basics

Start here

What an ADU is and what you can build.

  • An ADU (Accessory Dwelling Unit) is a smaller secondary home built on the same property as a primary residence. ADUs can be attached to the main home, converted from existing space, or built as separate structures depending on zoning and site conditions.

    Common uses include:

    • Rental income

    • Guest housing

    • Multigenerational living

    • Home offices or studios

    • Housing for aging parents or adult children

  • A DADU (Detached Accessory Dwelling Unit) is a standalone ADU that is physically separate from the main house.

    Examples include:

    • Backyard cottages

    • Tiny homes

    • Detached garage apartments

    A DADU functions like a small independent home with its own living space, kitchen, bathroom, and entrance.

  • An ADU is the general category for a secondary living unit on a property.

    A DADU is a specific type of ADU that is detached from the main home.

    Examples:

    • Garage conversion = ADU

    • Basement apartment = ADU

    • Backyard cottage = DADU

  • We can build nearly any architectural style, including:

    • Modern

    • Cottage

    • Craftsman

    • Farmhouse

    • Minimalist

    • Contemporary

    • Entry-Level Studio Designs

    We also offer customizable siding, paint, and finish options.

02 - Your Property

Building on your land

Feasibility, zoning, size, and site conditions.

  • It depends on:

    • County and zoning regulations

    • Lot size

    • Utility access

    • Septic or sewer capacity

    • Scenic Area restrictions

    • Setback requirements

    We can help determine if your property qualifies.

    You can contact us directly or submit your property information for a site review and feasibility analysis.

    Reports can be sent to:
    quantumbuildersnetwork@gmail.com
    design@gorgeadu.com

  • This depends on county regulations and zoning requirements.

    Common Klickitat County considerations:

    • Detached ADUs often must be within 200 feet of the primary home

    • Shared driveway access is commonly required

    • Existing wells usually must serve both dwellings

    • Septic capacity must be verified

    • Scenic Area parcels may have additional restrictions

    Maximum square footage varies by jurisdiction.

  • Height limits depend on:

    • Zoning

    • Setbacks

    • Roof design

    • Scenic Area restrictions

    • Site-specific conditions

    In many cases, reasonably tall structures are allowed if they meet county requirements.

  • Possibly.

    If the existing septic system has enough remaining capacity, the ADU may be able to tie into it. This typically requires:

    • Septic evaluation

    • Capacity verification

    • County approval

    In some cases, upgrades or system expansion may be required.

03 - Cost & Timeline

Budget and timing

What to plan for and how long it takes.

  • Most ADU projects we are currently seeing range between:

    $200,000 – $400,000+

    Pricing depends on:

    • Site conditions

    • Utilities

    • Septic requirements

    • Design complexity

    • Size

    • Interior finishes

    • Permitting and engineering

  • Our Initial Site Review is a $500 value.

    If the property is ultimately determined to be non-viable for an ADU project, that fee is refunded.

  • Permitting timelines vary by county, parcel conditions, and project complexity.

    Using template designs and prescriptive building methods can significantly reduce approval timeframes.

    Typical Timelines

    Klickitat County

    • Best case: ~1 month

    • Typical rural ADU: 2–3 months

    • Scenic Area or complex parcel: 4–6+ months

    Hood River County

    • Inside city limits with clean lot: 1.5–2.5 months

    • Rural county parcel: 2–4 months

    • Scenic Area / EFU complications: 4–8+ months

04 - Working Together

Working with us

How we collaborate on your project.

  • Yes.

    We understand many homeowners have construction skills and may want to contribute to keep costs down.

    As long as homeowner participation helps workflow and does not create delays, collaboration is welcome.

    However:

    • Homeowner-completed work may require signed waivers

    • Any homeowner-touched work may be exempt from certain final product complaints or warranties

Still have questions?

Tell us about your property and goals, and we’ll help you figure out what’s possible.

Contact US