ADU Economics For North Gilham Investors

Thinking about adding an ADU to a North Gilham property near Coburg and wondering if the numbers pencil? You are not alone. Many small investors want dependable cash flow or space for multigenerational living, but the rules and costs can feel murky in this corridor. In this guide you will learn how jurisdiction affects what you can build, what typical costs look like in Lane County, and how to build a clean pro forma so you can decide with confidence. Let’s dive in.

Start with jurisdiction

Before you sketch a floor plan, confirm which agency governs your parcel. In North Gilham, lots can fall under the City of Eugene, the City of Coburg, or unincorporated Lane County. That single fact drives what is allowed, how big you can build, and how fast you can permit.

• Size and height limits change by city. That affects rentable square footage and your rent potential.
• Programs and plan sets vary. Eugene has pre-approved ADU plan options that can streamline review and reduce soft costs.
• Utilities matter. City sewer and water can lower hookup costs. Septic or well adds complexity and expense.
• Parking and occupancy rules differ. Owner-occupancy or short-term rental rules can shape your strategy.

If you take one step today, make it this: confirm jurisdiction through the Lane County assessor or city GIS, then call the planning and building counter for that agency to verify standards and fees.

How to verify your governing agency

• Pull the parcel map from the Lane County assessor or city GIS.
• Ask the planning department to confirm which code applies to your exact site.
• Request an ADU standards summary, fee schedule, and submittal checklist so you can budget with fewer surprises.

Eugene ADU options at a glance

Many North Gilham parcels sit within or near Eugene’s planning area. Eugene has explicit ADU policies and a program with pre-approved plan sets. If your parcel is in Eugene, this can lower design time, reduce review risk, and shorten your timeline.

What to look for on Eugene’s ADU resources when you call or visit in person:

• Where ADUs are allowed by zone and whether the site meets setbacks and lot coverage limits.
• Maximum ADU size, height limits, and definitions for detached, attached, and junior ADUs.
• Pre-approved plan sets that already align with zoning. Using one can shrink soft costs and speed approvals.
• A clear permitting checklist that covers site plan, floor plans, and utility details.

Tip: If your lot fits a pre-approved footprint, compare two to three plan sets against your setbacks and any easements. A good fit can shave weeks off your calendar and save on design.

Coburg and Lane County checks

Coburg has its own municipal code. It can be more restrictive or just different than Eugene. Confirm the city’s size, lot coverage, and parking rules for ADUs. Many Coburg properties have municipal water and sewer. If so, your utility hookups may be simpler and less costly than a septic solution.

If your parcel is in unincorporated Lane County, expect ADU rules to follow the county land use code. Parcels on septic or well often need additional studies and may face higher soft costs. Get the county’s development standards and a current fee schedule before you finalize your budget.

What ADUs cost in this market

Costs vary by design, finish, and site complexity, but these regional ranges can help you draft a first-pass budget. Always confirm with local bids.

Hard construction costs

• Detached ADU: about $200 to $400 per square foot. Studios and simple one-bed units with basic finishes land toward the low end. Larger or higher-finish units trend higher.
• Attached ADU: often lower per-square-foot incremental cost since you share walls, roof, and utility runs with the main house.

Soft costs to plan for

• Design and engineering: roughly 5 to 10 percent of construction cost if custom. Pre-approved plans can reduce this.
• Permits and plan review: often 1 to 3 percent of construction cost, but fees vary by jurisdiction.
• Utility hookups:
  • Water and sewer taps or lateral work may be a few thousand dollars to more than $15,000 if mains need extension or capacity upgrades.
  • Electrical upgrades can run about $2,000 to $10,000, higher if a transformer or service relocation is needed.
  • Stormwater and drainage fixes vary by site.
• Site work: grading, retaining walls, driveway or parking, and landscaping can add $5,000 to $40,000 depending on slope and access.
• Surveys and studies: $1,000 to $5,000 or more if slope or septic issues apply.
• Financing and contingency: hold a 10 to 15 percent contingency and include loan fees and interest in your pro forma.

A conservative planning rule is to expect soft costs around 15 to 30 percent of hard construction cost. If you use a pre-approved plan on a simple site, you may land below that range.

Time and carrying costs

• Timeline: a pre-approved plan with city utilities can trim calendar risk. Otherwise, budget several months for design and permits and 3 to 6 months or more for construction.
• Carry costs: include mortgage, taxes, insurance, and interest during construction in your model.

Build a clear North Gilham pro forma

Work from the lot up. This checklist keeps you focused on the inputs that change the math.

• Jurisdiction: Eugene, Coburg, or Lane County.
• Lot constraints: setbacks, easements, slope, and driveway access.
• ADU size target: for example, 600 to 900 square feet based on zoning and rent goals.
• Cost assumptions: hard cost per square foot and total hard cost based on two or more local estimates.
• Soft costs: design, permits, utility hookups, and site work as line items or a percent of hard cost.
• Financing: loan to cost, rate, interest-only period, and draws.
• Rent comps: ADUs or small apartments in Coburg or north Eugene with similar size and parking.
• Operating expenses: tax increase, insurance, management, repairs, and utilities you will cover.
• Vacancy: 5 to 10 percent for long-term rentals.
• Exit plan: hold for cash flow, refinance after stabilization, or sell to capture value added.

Example calculation

This simple illustration shows how the pieces come together. Use local bids and comps to refine.

• Size: 700 square feet detached ADU.
• Hard cost: $275 per square foot equals $192,500.
• Soft costs: 20 percent equals $38,500.
• Total development cost: about $231,000.
• Rent: based on area one-bed comparables, assume $1,200 to $1,600 per month. Annual gross is $14,400 to $19,200.
• After a 40 percent load for expenses and vacancy, estimated NOI is $8,640 to $11,520.
• Cash-on-cost yield: about 3.7 to 5.0 percent. Decide if that meets your target once you factor in financing and potential post-stabilization refinance.

Rules that shape returns

Policy details affect both rent options and lender views. Verify these items with your governing agency before you commit to a design.

• Owner-occupancy: some jurisdictions have required an owner to live on site. Many have updated rules to add flexibility. Confirm current policy.
• Short-term rentals: ADUs used as vacation or short-term rentals may need separate permits or may not be allowed. Check before you model nightly rates.
• Building code: fire separation, egress windows, insulation, and energy code compliance affect layout and cost.
• Taxes and assessment: ADU construction typically increases assessed value. Set expectations for property tax changes and plan for rental income taxation.
• Insurance: you may need a landlord endorsement or an umbrella policy when you add an ADU.

Action checklist for North Gilham sites

Follow this order of operations to save time and reduce change orders.

1. Confirm jurisdiction and zoning with the Lane County assessor and the applicable planning department.
2. Request the ADU standards summary, fee schedule, submittal checklist, and any pre-approved plan options.
3. Ask utilities to review capacity and connection requirements for water, sewer, power, and stormwater.
4. Commission basic site feasibility: survey, topography, and utility locate. If septic is involved, plan for additional studies.
5. Compare attached versus detached ADU options for fit and cost.
6. Get two contractor estimates using the same scope so you can compare apples to apples.
7. Build a conservative pro forma that includes soft costs, contingency, and carry costs with realistic rent comps.
8. Review tax and insurance impacts with your CPA and insurer.

How Parker Heights Realty helps

You want clear answers, realistic numbers, and a smooth path from concept to cash flow. Our small, principal-led team specializes in helping local buyers and small investors source lots, run site-specific ADU checks, and manage the details from offer through close. We lean on local relationships and a repeatable process to position your project for success. When you are ready to explore an ADU in North Gilham or near Coburg, we are here to help you evaluate the lot, the rules, and the returns.

Ready to run the numbers on your property or find a lot that fits an ADU plan? Contact Parker Heights Realty to schedule a free consultation and home valuation.

FAQs

What should North Gilham investors check first for an ADU?

• Confirm your parcel’s jurisdiction and zoning, then request ADU standards, fee schedules, and a submittal checklist from the governing agency.

How do Eugene’s pre-approved ADU plans help investors?

• They can reduce design hours, lower soft costs, and shorten plan review if a plan fits your lot’s setbacks, height limits, and utilities.

What are typical ADU hard and soft costs in Lane County?

• Recent regional ranges show about $200 to $400 per square foot for detached builds, with soft costs often 15 to 30 percent of hard cost depending on design and site.

How long does an ADU project take near Coburg?

• Plan for several months to design and permit and 3 to 6 months or more to build. Pre-approved plans and city utilities can shorten the timeline.

What rent should I underwrite for a North Gilham ADU?

• Use local comparables for ADUs or small apartments with similar size, finishes, and parking. The example in this guide models $1,200 to $1,600 per month for a one-bedroom.

Do owner-occupancy or short-term rental rules limit ADU use?

• Policies differ by jurisdiction and can change. Verify owner-occupancy requirements and short-term rental regulations with your planning department before finalizing your plan.