Custom Home Feasibility in King County, WA
A feasibility study identifies the regulatory, environmental, and site-specific factors that determine what can be built on a property in unincorporated King County. King County’s zoning, rural development standards, critical areas regulations, and drainage requirements often shape the scope of custom home projects. Our feasibility analysis for King County includes:
Zoning, allowable uses, and development standards (King County Code Title 21A)
Setbacks, height limits, lot coverage, and rural density requirements
Critical areas (steep slopes, erosion hazards, landslide-prone areas, wetlands, streams, floodplains, and wildlife corridors)
Shoreline jurisdiction requirements for lakes, rivers, and major streams
Tree retention, vegetation management, and clearing limits
Sewer and water availability (or verification of septic and well requirements)
Preliminary stormwater considerations under the King County Surface Water Design Manual
Access, driveway limitations, private road standards, and fire apparatus requirements (KCFD)
High-level grading and site suitability
Our feasibility reports identify potential constraints and outline the steps necessary for permitting through King County DLS (Department of Local Services).
Civil Engineering for Custom Home Sites in King County
After feasibility confirms the site is buildable, we provide complete civil engineering services tailored to King County’s rural and suburban development requirements. This includes:
Site plans meeting King County DLS submittal standards
Grading plans with slope analysis, earthwork calculations, and retaining wall considerations
Stormwater design (infiltration feasibility, dispersion systems, flow control, and conveyance requirements)
Infiltration testing coordination based on soil and groundwater conditions
Driveway design, slope compliance, and private road requirements
Utility design for water, sewer, or well/septic integration
Erosion and sediment control plans
Earthwork calculations
Right-of-way or frontage improvements when required by Roads Services
Construction documents for full permit review
Our plans are prepared to meet King County’s drainage and critical areas standards while supporting the architectural and geotechnical teams.
Permit Management & Project Coordination in King County
King County’s permitting process often requires multiple studies and coordinated reviews. We manage this process to help maintain predictable timelines:
Preparation of complete permit application packages
Responses to correction comments from DLS, Roads Engineering, Fire, and Environmental Review
Coordination with surveyors, geotechnical engineers, septic designers, well drillers, arborists, architects, and builders
Monitoring review timelines and required resubmittals
Ensuring compliance with King County Code and the Surface Water Design Manual
This improves review efficiency and reduces the likelihood of delays during pre-construction.
Common King County–Specific Constraints
Wetlands, Streams & Wildlife Corridors
Many King County rural areas—such as Fall City, Maple Valley, Ravensdale, and parts of Kent—contain protected wetlands, buffers, and wildlife habitat networks.
Septic & Well Requirements
Areas without sewer require septic system design and adequate soil evaluations, which directly influence building area and tree removal.
Stormwater Requirements
The Surface Water Design Manual often triggers infiltration systems, flow control facilities, or engineered dispersion depending on site conditions.
Steep Slopes & Geologic Hazards
Parcels on the Plateau, in the foothills, or near ravines commonly require geotechnical review and slope stability considerations.
Private Roads & Access Limitations
Long driveways, private roads, and fire turnaround requirements may influence site layout and grading.
Evaluating these elements early helps prevent redesigns and unexpected expenses.
Start Your King County Custom Home Feasibility Review
A successful custom home project in King County begins with accurate feasibility and a clear understanding of local regulations. McInnis Engineering provides feasibility studies, civil engineering, and permit management to support homeowners and builders throughout the review process.
Contact us to begin a feasibility assessment or discuss your King County property.