Adding an ADU in Bend: The Pre-Approved Plan Loophole That Saves You Money

Adding an accessory dwelling unit (ADU) to your Bend property can create flexible housing, support multigenerational living, or provide rental income. However, the design, permitting, engineering, and construction process can become expensive if you start with a completely custom plan.

Bend’s pre-approved ADU program offers a more efficient path. By selecting a design that has already passed building plan review, you may reduce architectural and engineering expenses while simplifying the permit process. It is not a way to bypass zoning, site review, or construction standards, but it can eliminate unnecessary duplication during the early stages of your project.

Here is how the program works and what you should know before building an ADU in Bend or Deschutes County.

Understand What “Pre-Approved” Means in Bend

The City of Bend’s Pre-Approved ADU Program allows property owners to use building plans that have already been reviewed for applicable building code requirements. The Bend Chamber’s Pre-Approved ADU Design Library provides several examples, including compact one-bedroom homes, two-bedroom layouts, and accessible single-level designs.

Available plans range from approximately 500 to 799 square feet. Depending on the design, you may find options for a detached backyard cottage, an above-garage unit, or a compact home with an efficient open layout.

The important distinction is that the building plan is pre-approved, but your property is not automatically approved. You still need a site-specific plan showing how the ADU will fit on your lot, including setbacks, utilities, drainage, access, and other zoning considerations.

Additionally, the City of Bend states that its pre-approved plans are licensed for permitting use within Bend city limits. If your property is in unincorporated Deschutes County, the plan may require permission from the designer and a separate review by the County.

Start by Confirming Your Jurisdiction and Zoning

Before choosing a design, determine whether your property is inside Bend city limits or within unincorporated Deschutes County. This distinction affects which rules apply, where you submit your application, and whether a Bend pre-approved plan can be used in its original form.

The Bend Chamber’s ADU Guide explains the broad differences between detached, attached, interior, garage-conversion, and above-garage ADUs. The guide also notes that ADUs may be permitted in certain rural Deschutes County zones.

You should confirm the following before committing to a plan:

• Your property’s zoning designation

• Whether an ADU is allowed on your lot

• Required setbacks from property lines and existing structures

• Maximum building height and floor area

• Lot coverage and design requirements

• Parking and access requirements

• Water, sewer, electrical, and stormwater considerations

• Any overlay districts or wildfire hazard designations

Consequently, a short zoning review at the beginning can prevent expensive changes after you have purchased plans or started site work. A qualified builder can help identify potential issues early, but you should also verify current requirements with the appropriate planning and building department.

Choose a Pre-Approved Design That Fits Your Property

A pre-approved plan can save money only if it fits your site and your intended use. For example, a 576-square-foot one-bedroom plan may work well as a private guest suite or long-term rental, while a larger two-bedroom layout may better serve aging parents or adult children.

Review each plan for more than its appearance. Consider how the structure will be placed on your property, where occupants will park, how guests will reach the entrance, and whether construction equipment can access the site.

You should also evaluate:

• Bedroom and bathroom configuration

• Storage capacity

• Laundry location

• Window placement and privacy

• Kitchen size and appliance layout

• Accessibility needs

• Energy efficiency

• Future resale or rental flexibility

The designer may offer modifications, but significant changes can reduce the financial advantage of using a pre-approved plan. For instance, moving structural walls, changing the roofline, or altering the foundation may require additional architectural or engineering review.

The best approach is to select a design that already meets most of your needs. Minor site adaptations are generally more manageable than turning a standard plan into a custom home.

Work With a Qualified Local Builder

After selecting a design, choose a builder who understands Central Oregon construction conditions and local permitting procedures. ADU projects require coordination between design, excavation, foundations, utility connections, framing, mechanical systems, and final inspections.

Your builder should be able to explain:

• Which work is included in the construction estimate

• Which costs are separate soft costs

• Who prepares the site plan

• Who coordinates permit submissions

• How utility connections will be handled

• What allowances apply to fixtures and finishes

• How change orders are documented

• What schedule is realistic for your property

Transparent pricing is crucial. A low initial number may not include demolition, trenching, utility upgrades, rock excavation, drainage improvements, permit fees, or wildfire-resistant materials. Request a detailed estimate that separates construction costs from design, engineering, permitting, site development, and utility expenses.

At Stone Fire Construction and Maintenance LLC, we bring 20 years of combined industry experience, including 10 years serving homeowners throughout Central Oregon. We are licensed, bonded, and insured under CCB# 243975, and we focus on clear communication, fair pricing, and getting the job done right the first time.

Plan Carefully for Site Preparation and Utilities

The pre-approved building plan does not eliminate site preparation. In many cases, the site itself creates the most significant variables in an ADU budget.

Your builder may need to evaluate soil conditions, slope, drainage, excavation access, existing trees, retaining walls, and the location of underground utilities. A detached ADU may also require new water, sewer, electrical, gas, or telecommunications connections.

Common site-related expenses include:

• Excavation and grading

• Foundation preparation

• Utility trenching

• Sewer or water connection fees

• Electrical service upgrades

• Driveway or pathway improvements

• Stormwater management

• Demolition or removal of existing structures

• Landscaping repair after construction

For this reason, it is essential to inspect the property before finalizing the construction price. A thorough site review can identify conditions that are not visible from the plan set and help you establish a more accurate budget.

Account for Deschutes County R327 Wildfire Requirements

Wildfire-resistant construction is a critical consideration in Central Oregon. Depending on your property’s location and hazard designation, Deschutes County requirements associated with Oregon Residential Specialty Code Section R327 may affect the design and material selections for your ADU.

Potential requirements can include:

• Class A or Class B roofing, depending on the applicable standard

• Ember-resistant or ember-resistant screened vents

• Ignition-resistant siding and exterior materials

• Protected soffits and eaves

• Appropriate requirements for windows, doors, decks, and other projections

• Defensible space and property access considerations

Do not assume that a plan pre-approved by the City of Bend automatically satisfies every Deschutes County wildfire requirement. City and County jurisdictions may apply different review procedures, and a rural property may have site-specific wildfire standards that require plan modifications.

If you are building outside Bend city limits, confirm the requirements with Deschutes County’s ADU resources and the County Building Division. Your designer and builder should coordinate to verify roofing, vents, siding, glazing, eaves, and other exterior components before construction begins.

These measures may add to the initial cost, but they serve an essential purpose. Proper wildfire-resistant construction can improve the structure’s ability to withstand ember exposure and protect your long-term investment.

Estimate the Savings From Pre-Approved Plans

The main financial advantage of a pre-approved design is reducing duplicated professional work. A fully custom ADU may require extensive architectural drafting, structural engineering, plan coordination, and revisions before the permit application is ready.

With a pre-approved plan, much of the base design and building-code review has already been completed. You may still pay for:

• The plan license or purchase

• A site-specific plan

• Structural or engineering adjustments

• Energy-code documentation

• Surveying or geotechnical services, when required

• Permit and development fees

• Utility and system development charges

• Wildfire-related modifications

• Builder coordination and project management

The actual savings vary by project. A straightforward urban lot with accessible utilities may benefit substantially, while a sloped or wildfire-prone property may require more engineering and site work. The right question is not whether the pre-approved plan eliminates all soft costs. It is whether it reduces the amount of custom design and review needed to move your project forward.

A detailed, written estimate is the best way to evaluate the difference.

Build for Long-Term Flexibility

Your ADU should meet your current needs while remaining useful in the future. Consider adding accessibility features such as a no-step entrance, wider doorways, reinforced bathroom walls for future grab bars, and a curbless shower.

Energy efficiency also deserves attention. High-performance insulation, efficient windows, and a ductless heat pump can improve comfort while helping control operating costs. Separate heating and cooling controls may be particularly valuable when the ADU is occupied by tenants or family members with different preferences.

If you plan to rent the unit, design for durable finishes and straightforward maintenance. If the ADU will support aging parents, prioritize safe circulation and accessible fixtures. Thoughtful planning now can prevent expensive renovations later.

Why Stone Fire Construction and Maintenance LLC Can Help

An ADU is a major investment, but the process becomes more manageable when you have one accountable construction partner. Stone Fire Construction and Maintenance LLC provides responsive, reliable building services for homeowners and property owners throughout Central Oregon.

Our team combines local experience with a commitment to transparent pricing and practical project management. From site preparation and framing to finish work and final details, we focus on quality workmanship and completing the job correctly the first time.

If you are considering a pre-approved ADU in Bend, contact Scott Bender at 541-948-3775 or stonefirebuilders@gmail.com. We can help you evaluate your property, review the construction implications of a selected plan, and develop a clear path toward a safe, functional, and lasting ADU.

For additional planning guidance, read our guide to custom home additions, multigenerational living, and ADUs.