GroundUp

Buildability Report

18424 SE 392nd St, Auburn, WA 98092

Unincorporated King County, Washington

This sample parcel looks viable for a homesite, but the biggest swing factors are septic confirmation, utility extension distance, and whether site grading stays modest after a field visit.

Analysis Confidence

This example combines typical parcel screening signals GroundUp surfaces early: jurisdiction context, utility and septic uncertainty, terrain screening, and the next actions that reduce risk before closing.

Overall Quality
MEDIUM

Assessment Factors

Zoning appears compatible with residential use

Confidence: MEDIUM
PASS

The sample parcel is presented as a low-density residential site where a single-family homesite is likely permissible, subject to normal setback, lot coverage, and environmental overlay checks.

To Increase Confidence:

Verify zoning code, setbacks, and overlays with the county planning department.

Septic should be treated as a key diligence item

Confidence: MEDIUM
WARNING

The parcel profile is consistent with an on-site septic scenario, but soil suitability and drainfield layout remain major go/no-go questions until perc and design work are completed.

To Increase Confidence:

Complete perc testing and engage a septic designer.

Water access may require a well or extension analysis

Confidence: MEDIUM
WARNING

A buyer should expect to verify whether public water is available nearby or whether a private well path is more realistic. Either route can materially affect schedule and budget.

To Increase Confidence:

Call the local water provider and review nearby well data.

Power extension risk looks manageable in this sample

Confidence: MEDIUM
PASS

This example assumes distribution power is not unusually remote, making electric service more of a pricing and coordination task than a fatal site constraint.

To Increase Confidence:

Request a utility extension estimate with parcel access details.

Terrain appears workable for a standard homesite

Confidence: MEDIUM
PASS

The sample report assumes moderate slope conditions that should allow development without extreme retaining, hillside engineering, or unusually expensive driveway construction.

To Increase Confidence:

Review topography and conduct a site walk with a builder or engineer.

Road access appears straightforward in this sample

Confidence: MEDIUM
PASS

The example parcel is shown with plausible frontage on a public road, which reduces the chance that legal access becomes a major surprise item during due diligence.

To Increase Confidence:

Confirm legal access, frontage, and driveway requirements with parcel maps and title review.

Environmental overlays still need confirmation

Confidence: LOW
VERIFY

Wetlands, floodplain boundaries, buffers, and critical-area overlays can materially shrink a build envelope even when a parcel looks promising on first pass.

To Increase Confidence:

Run a live report and verify mapped overlays with county GIS and consultants.

Estimated Development Costs

Typical range for well-characterized sites: $120,000 – $175,000

$95,000 – $215,000
Cost Confidence: MEDIUM
Septic system
MEDIUM$25,000 – $55,000

⚠ Complete perc testing and septic design.

Water connection or well
LOW$15,000 – $50,000

⚠ Confirm service availability and request provider guidance.

Site prep, driveway, and grading
MEDIUM$30,000 – $65,000

⚠ Review access and grading needs with a site contractor.

Why is this range wide?

  • • Final septic design has not been tested
  • • Water source and extension costs are not confirmed
  • • Environmental constraints could reduce the buildable area

To narrow this: Confirm septic feasibility, utility availability, and environmental overlays before relying on a narrowed budget.

This sample range reflects a typical Washington homesite with moderate utility work, septic dependency, and ordinary site preparation.

Identified Risks

Septic outcome could materially change the deal
CRITICAL

If soils require a more complex system or the best drainfield area conflicts with setbacks or slope, development costs can rise quickly.

Utility assumptions may hide infrastructure cost

Even a promising parcel can become less attractive if water or power extensions are longer or more constrained than expected.

Recommended Next Steps

1
Verify zoning and overlays with the county
VERIFY

Confirm permitted use, setbacks, minimum lot standards, and whether any critical-area overlays shrink the practical build envelope.

Impact: Prevents spending on a parcel that cannot support the intended homesite.

2
Order septic feasibility work early
TEST

Treat septic as an early decision gate. A failed or expensive design outcome can quickly change whether the parcel still makes sense.

Impact: Clarifies homesite viability and one of the largest off-house budget items.

3
Request utility availability guidance
VERIFY

Reach out to the likely water and power providers with the parcel location to understand connection paths, timelines, and any unusual extension requirements.

Impact: Narrows infrastructure budget and schedule risk.

4
Walk the site with a builder or civil professional
CONTACT PRO

A field visit can quickly identify driveway challenges, drainage concerns, staging constraints, and the most efficient build area.

Impact: Improves grading, access, and site-prep budgeting before closing.

Example Report

Ready to evaluate your own parcel?

This sample shows the report structure and tone. Run a real parcel search from the home page to get address-specific findings.

Analyze Your Parcel