A unit lot subdivision divides a residential development into individual ownership lots while the parent lot remains the basis for many development standards. The unit lines need to work with the approved buildings, access, utilities, drainage, and shared areas.

For these reasons, clients bring us into the design discussion early. We can coordinate the unit lot subdivision with your architect and civil engineer while the layout is still flexible.

Understand what the unit lot represents

Seattle’s platting guidance explains that unit lots support separate ownership within an approved residential development. They do not become independent legal building sites simply because they have separate boundaries.

The development must satisfy the standards that apply to the parent lot. That relationship may limit future changes to an individual unit. Your plat and ownership documents need to make those limits clear.

Start with the approved or proposed development and its ownership plan. Drawing small lots around buildings is only one part of the work.

Establish the parent lot first

Before we place unit lines, we need a reliable picture of the property. Send us the title report, complete exception documents, prior surveys, and current design files.

We’ll define the survey work needed to establish boundaries, monuments, legal descriptions, and relevant site conditions. We’ll also account for easements, rights-of-way, critical areas, and other constraints before they affect every unit.

Your boundary and topographic survey should support both the subdivision and the design team’s needs. Keep all disciplines working from the same base.

Choose the unit lines deliberately

A line may follow a party wall, building footprint, yard edge, or another agreed location. The right placement depends on the approved design, ownership, maintenance, utility layout, and financing requirements.

Check more than the ground-floor footprint. Eaves, decks, stoops, stairs, foundations, retaining walls, and below-grade elements may cross a proposed line. That may call for a different line or an easement.

Tell us when the building geometry changes. A revised roof or stair can affect the subdivision even if the unit count stays the same.

Decide who owns and maintains shared areas

Drive aisles, walkways, open space, landscape areas, utility corridors, and stormwater facilities may serve several units. Each needs an intentional ownership and maintenance arrangement.

Washington’s unit-lot provisions address common ownership of portions of the parent lot that are not subdivided into individual unit lots. Coordinate the arrangement with your attorney and title team so the recorded geometry and legal documents agree.

Ask practical questions: who can enter to repair the facility, who pays, and can they reach it without crossing land they have no right to use? Resolve those questions before separate owners inherit them.

Make access work for every unit

Vehicle access, pedestrian circulation, fire access, and refuse collection may follow different routes. Map each route and the rights needed to keep it usable after the units are sold.

A shared drive may need access and maintenance provisions. A walkway may cross another unit lot or common area. Emergency access can impose requirements that affect the layout.

We’ll coordinate the surveyed routes with the design team. Your legal team should confirm that the easements and agreements support the intended use.

Align utilities and drainage with ownership

A unit may have individual services, shared systems, or both. Connect the utility discussion to the unit-line discussion before finalizing either.

Coordinate meters, mains, laterals, cleanouts, vaults, transformers, drainage facilities, and maintenance corridors with the civil engineering plans. Show where services cross ownership boundaries and identify the rights they require.

Stormwater facilities also need space and access for ongoing maintenance. A system can fit on a drawing and still be difficult to operate if the ownership arrangement is unclear.

Keep the drawings aligned

Check three current documents together:

• Architectural plan: buildings, projections, exterior spaces, and unit numbering.
• Civil plan: grading, drainage, access, utilities, and shared infrastructure.
• Subdivision survey: parent boundary, unit lots, common tracts, easements, and plat notes.

Agree on a coordination point before finalizing the subdivision documents. Each discipline needs the others’ current files in a usable format. A late revision should trigger a deliberate check of the affected lines, rights, and notes.

Confirm the permit sequence and disclosures

Seattle requires a land use or construction permit approving the specific residential development before the unit lot subdivision. Depending on the number of unit lots, the project may follow a short or full subdivision process. We’ll confirm the applicable route with SDCI and coordinate the survey work with the permit sequence.

Tip 213A covers short subdivision applications, but SDCI cautions that its guidance may lag regulatory changes. We’ll check the current requirements for the project rather than rely on the tip alone.

The plat must include notes explaining its relationship to the approved development and the limits on later changes or redevelopment. Purchasers must also be notified of the unit lots’ legal status. We’ll confirm the exact plat language and coordinate the purchaser notice requirements with the project’s legal and title reviewers.

A pre-submittal check you can use

• Parent lot: title, boundary, and relevant site conditions are established.
• Design: architectural and civil files use the same survey base and current layout.
• Unit lines: check building footprints and projections.
• Access: define routes and supporting rights for every unit.
• Utilities: coordinate service, shared systems, and maintenance rights.
• Common areas: clarify ownership and maintenance responsibilities.
• Documents: identify easements, agreements, disclosures, and plat notes.
• Permitting: confirm the current approval route and intake requirements.

Send us those materials with your ownership concept, lender or title requirements, site contacts, and schedule. If you’re still in concept design, we can start with a focused feasibility review.

Common questions

Does each unit lot become a separate building site? No. Its development rights remain tied to the approved project and the parent-lot standards.

Does every unit lot project use a short subdivision? No. Seattle identifies both short- and full-subdivision paths. Confirm which applies to the proposed unit count and project.

Can unit lines follow the building footprints? Sometimes. Check projections, foundations, utilities, access, and maintenance needs before settling on that arrangement.

Should we wait until design is complete? Bring us in while the layout can still change. The final subdivision must align with the approved development, but early coordination helps identify conflicts.

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