The Investor’s Checklist for a Buildable Lot

Every new investor wants to find the “perfect lot” - flat, buildable, zoned just right, and primed for a DADU or multi-unit build. But here’s the reality: perfect is a myth - only vetted and viable are real.

The difference between a profitable build and a nightmare project isn’t price or design.
It’s how well you understand what’s under the dirt and around the edges before you close.

If you don’t check utilities, setbacks, slopes, or trees before you buy, you’re not investing - you’re gambling.

Here’s the checklist every serious DADU investor should run before they write an offer.

Everything starts here. Before you think about architecture, cost, or rental income, confirm what you’re legally allowed to build. In Seattle, use the SDCI GIS Map to check:

  • Zoning type: SF 5000, RSL, LR1, etc.

  • Development standards: height limits, setbacks, lot coverage

  • Overlay zones: environmentally critical areas (ECA), shoreline, or tree protection

SF 5000 lots are gold for backyard investors - they typically allow one DADU and one AADU, meaning you can turn a single home into three income-producing units.

If zoning tells you what you can build, utilities tell you what you can afford to build.

You need to verify:

  • Sewer: Where is the main line? Is it on your property or across the street?

  • Water: Can you tap the existing line or need a new connection?

  • Power: Overhead or underground? Are upgrades required for added load?

  • Gas: Available on your side of the street or not at all?

Contact Seattle Public Utilities (SPU) and Seattle City Light (SCL) to request utility as-builts. These maps show exact locations of lines and connections.

Watch out for:

  • Sewer lines that run uphill (you’ll need an ejector pump - expensive).

  • Water meters located on the neighbor’s lot (easement nightmare).

  • Transformer upgrades (can add $10K–$20K fast).

Setbacks are the invisible lines that define your buildable area. In most Seattle zones:

  • Front setback: 20 feet

  • Side setback: 5 feet

  • Rear setback: 25 feet (varies by zone)

  • Max lot coverage: around 35% for structures

This means your 5,000 sq. ft. lot might only allow a 1,500–1,700 sq. ft. building footprint. Always sketch a quick “box layout” using setbacks to visualize what fits. Don’t rely on a broker’s word that the lot is “buildable.”

Sloped lots can look beautiful and destroy your margins. If your lot drops more than 4–6 feet front-to-back, expect additional:

  • Grading and retaining wall costs

  • Stormwater management plans

  • Engineering requirements

Ask your surveyor for elevation data and look for any steep slope ECA flags on the city map. A “flat” DADU foundation can cost $60K. Add slope, and you’re easily pushing $100K–$120K before you even start framing.

Seattle’s tree protection ordinance can derail an otherwise great project. If a “significant tree” (usually > 6” diameter or certain species) sits in your build area, you may be required to:

  • Preserve it and redesign around it

  • Hire an arborist for a report

  • Pay mitigation fees if removal is allowed

Order an arborist site visit early. Don’t assume you can cut down anything on your own property. Protected trees often control your entire footprint.

Your design might look great on paper, but can your tenants or buyers actually get to it?

Check for:

  • Alley access: Ideal for DADUs, simplifies parking and privacy.

  • Street access: Verify curb cuts and right-of-way clearance.

  • Driveway slope: Seattle limits driveway grades (usually max 15%).

If parking is tight, consider designs with zero-lot-line or tandem layouts - but confirm city approval before finalizing plans.

Don’t assume your lot is clean just because it’s listed. Always review the title report for easements, shared driveways or utility corridors. These restrictions can limit where you build or what you can do with the land.

A “10-foot utility easement” across your rear property line can erase your DADU’s entire footprint.

Check for:

  • Environmental Critical Areas (ECA)

  • Wetlands or flood zones

  • Historic overlays or landmark restrictions

These trigger extra permitting layers that can extend your timeline by 3–6 months. SDCI’s ECA map will show you these instantly - if you see flags, budget extra for consultants and patience.

Once your lot passes the physical tests, study the neighborhood economics.

Ask:

  • Are new builds or DADUs selling nearby?

  • What’s the average ARV for finished homes?

  • Who’s your end user - long-term renters, condo buyers or multi-gen families?

Walk the block. If you see fresh construction or recent sales north of $1.5M, your feasibility odds are strong.

A lot isn’t just dirt - it’s a decision tree. Before you commit, define your path:

  • Hold: Build and rent both units.

  • Flip: Build, condo-ize and sell one or both.

  • Hybrid: Refinance, pull equity, repeat.

Your financing, design and contractor choice all depend on this decision.

Pro tip: Always structure your purchase in an LLC if you plan multiple exits. It simplifies liability and refi options later.

Finding a “buildable” lot isn’t luck - it’s discipline. Every strong investor knows: the deal is won in due diligence, not design.

When you verify zoning, utilities, setbacks, slope, and trees upfront, you’re not just avoiding mistakes - you’re engineering margin before you even write the offer. That’s how you stay ahead of the pack.

Learn how to analyze lots like a developer - and spot $300K opportunities before anyone else sees them.

Stephen Husted