You found the perfect corner for a cottage, and then a neighbor mentions a shared sewer line under it. That is how DADU easement restrictions usually show up. A DADU, or detached accessory dwelling unit, is a separate home on the same lot as a house. An easement gives someone else a recorded right to use part of your land, and it can rule out a building spot that zoning would allow.

The fix is simple research before design. Two documents, a title report and a boundary survey, show what is recorded.

Details below reflect official Seattle and King County pages checked in October 2026. Confirm with city staff for your property.

What Is an Easement?

An easement is a legal right for a person, a utility or a neighbor to use a defined strip of your property for a set purpose. You still own the land underneath. The holder of the easement keeps the right to reach, maintain or pass over it.

Most easements stay with the land when it sells. A right granted decades ago can still bind you today.

Common Types on Seattle Lots

• Utility easements for sewer, water, power or communications lines.
• Shared driveway or access easements between neighbors.
• Drainage easements that carry stormwater across a lot.
• Side sewer agreements where two houses share one line.
• View or maintenance agreements recorded with an old plat.

Each type has its own terms. Some forbid any structure inside the strip, while others only ban permanent foundations.

Where to Find Recorded Documents

King County records deeds, easements, plats and surveys as public documents. The King County recorded documents guide explains what the Recorder’s Office holds and how to search it.

A preliminary title report from a title company lists the recorded items that affect your parcel. Ask for copies of every listed easement, not only the summary page. The wording inside the document is what limits construction, so read each one in full with your designer.

How Easements Show Up in the Permit

SDCI Tip 103 lists easements among the items for an enhanced site plan, including the King County recording number. Plan reviewers compare the site plan against the survey. A cottage drawn over a recorded easement can stall review until the conflict is resolved.

Your surveyor can plot easement lines from their legal descriptions. That drawing becomes the base for your site plan.

Shared Driveways and Access Rights

A shared driveway can affect both construction and daily life. Crews may need to stage equipment on a strip your neighbor has a right to use. Blocking that strip, even for a day, can break the agreement.

Talk with the other party early. A written understanding about construction access saves friction later. The post on construction access covers staging on tight lots.

New Lines Your Cottage May Need

Easements work in both directions. Your new unit needs water, sewer and power, and the shortest route is not always across your own land. If a new line would cross a neighbor’s lot, you may need a new recorded easement from that neighbor.

On alley lots, power can arrive from poles along the alley. Seattle City Light reviews new or changed electrical service, so ask early where the line would run. A short conversation can show whether your own lot offers a clear path.

Sewer routing deserves the same attention. A side sewer that runs under a neighbor’s yard may already depend on an old agreement. The post on sewer connections covers the planning side.

Can an Easement Be Changed?

Sometimes. The holder may agree to relocate or release an easement, and that change must be recorded. A utility may allow a line to move if the owner pays for the work.

Changing a recorded right is a legal matter. A real estate attorney can explain options for your situation. Expect the process to involve the holder’s consent, new legal descriptions and a fresh recording with King County.

Relocation is not always worth it. Moving the cottage a few feet may cost far less than moving a buried line, so compare both before you commit.

A Hypothetical Rainier Valley Lot

Picture an invented lot in Rainier Valley where the title report shows a 10 foot drainage easement along the rear line. The owner in this example planned a cottage right in that strip.

A survey plots the strip precisely. Shifting the cottage 6 feet toward the house clears it and still meets the 5 foot separation from the main building.

Common Easement Surprises

• Old side sewer agreements that never appeared in the sale paperwork.
• Utility strips wider than the visible pole line.
• Access rights that limit fencing or gates.
• Plat restrictions recorded generations ago.
• Easements benefiting a neighbor that also restrict landscaping.

Frequently Asked Questions

Does zoning override an easement?

No. Zoning sets what the city allows, while an easement is a separate private or utility right recorded on title. A cottage can meet every zoning rule and still conflict with an easement, so check both before you design.

Will the city find easements for me?

Not reliably. SDCI expects the applicant to show easements on the site plan. Your surveyor and title report are the sources, so order them before drawings start.

Can I build a deck over an easement?

It depends on the easement’s terms. Some allow light improvements that can be removed, and others bar any structure. Read the recorded document and ask the holder if anything is unclear.

Easement Checklist Before Design

• Order a preliminary title report.
• Request copies of every recorded easement.
• Have a surveyor plot each easement line.
• Note recording numbers for the site plan.
• Talk with neighbors who share access or utilities.

DADU easement restrictions are easiest to handle on paper, before a designer draws anything. The title paperwork and the survey drawing are what matter most. Both the lot eligibility review and the post on backyard setbacks cover the other placement limits, and more topics live in the zoning and lot suitability section.