Custom Home Feasibility in Seattle, WA
A feasibility study identifies the regulatory, environmental, and site-specific factors that determine what can be built on a property in Seattle. Seattle’s land use code, environmentally critical areas (ECAs), and drainage requirements are among the most complex in the region. Our feasibility analysis for Seattle includes:
Zoning, allowable uses, and development standards (SMC Title 23)
Setbacks, height limits, FAR, and lot coverage
Environmentally Critical Areas (steep slopes, landslide-prone areas, liquefaction, riparian corridors, wetlands, flood zones)
Shoreline district restrictions
Tree protection and exceptional tree designation
Sewer and water availability (SPU), side sewer considerations, and utility routing
Preliminary drainage and stormwater requirements under Seattle’s Stormwater Manual
Access and fire lane compliance (SFD)
High-level grading, retaining wall needs, and site suitability
Our feasibility reports define the development potential of the site and outline what is required for permitting through SDCI.
Civil Engineering for Custom Home Sites in Seattle
Once feasibility confirms that the lot is buildable, we provide complete civil engineering services tailored to Seattle’s regulations. This includes:
Site plans compliant with SDCI submittal requirements
Grading plans with cut/fill analysis and slope stabilization considerations
Stormwater design (On-Site Stormwater Management, Green Stormwater Infrastructure, and potential drainage review triggers)
Infiltration testing coordination for permeable soils (when applicable)
Driveway and access slope review, including maximum allowable driveway grades
Utility design for water, sewer, and power connections
Erosion and sediment control plans
Earthwork estimates
Right-of-way improvements when required by SDOT
Construction documents prepared for full SDCI review
Our plans are developed to meet the expectations of SDCI, SDOT, and SPU while supporting architectural and structural design teams.
Permit Management & Project Coordination in Seattle
Seattle permits often require multiple departments (SDCI, SDOT, SPU, SFD). We manage this process to maintain predictable timelines:
Preparation of complete permit submittals
Responses to correction comments
Coordination with surveyors, geotechnical engineers, arborists, architects, and builders
Tracking review milestones
Ensuring compliance with all Seattle-specific standards
This reduces delays and ensures all documents stay aligned with reviewer expectations.
Common Seattle-Specific Constraints
Environmentally Critical Areas (ECAs)
Many Seattle lots include slopes, landslide hazard areas, or liquefaction zones that require geotechnical evaluation.
Tight Urban Infill Conditions
Limited space can require precise grading, drainage design, and utility coordination with adjacent properties.
Drainage & Stormwater Requirements
Seattle’s stormwater code frequently triggers Green Stormwater Infrastructure (GSI) or infiltration-based solutions, depending on soil type.
Exceptional Trees
Tree protection can affect the building footprint and driveway alignment.
Right-of-Way Requirements
SDOT may require sidewalk, curb, or frontage updates depending on the project scope.
Identifying these items early helps avoid redesigns and unexpected costs.
Start Your Seattle Custom Home Feasibility Review
Accurate feasibility is the first step toward a successful custom home in Seattle. McInnis Engineering provides feasibility studies, civil engineering, and permit management to help homeowners and builders move through SDCI’s process efficiently.
Contact us to begin a feasibility assessment or discuss your Seattle site.