Residential Buildings Located Across Property Lines

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This handout describes how the City addresses new development (including new buildings, structures, additions, etc.) when there is an existing buiding on the site that crosses a property line.

First Steps

  • Draw a site plan that shows where the existing and proposed buildings are located on the site.
  • Include a north arrow, scale, and all property lines on the site plan.
  • Label the distance between the proposed structure and other structures on the site.
  • Label the distance between all structures and property lines.
  • Determine the zoning district of the site by visiting the PDS Zoning Map and searching by property address or tax parcel number. Zoning information may also be requested from a Planner by calling 253-591-5030.


  • A firewall between a garage and a dwelling is typically required if the two structures are separated by less than 10 feet.
  • For duplexes and townhomes, the common wall will be a firewall.
  • Proposals for new buildings and additions must provide building code separation. These separation distances require residential dwellings and accessory buildings (garages, sheds, etc.), to provide a minimum of 5 feet between the structure and property line, and 10 feet between two structures on the same property.  If the minimum separation distance is not provided, firewall separation may be used.
  • Firewalls are primarily installed when walls are parallel to one another, rather than perpendicular.

Group Buildings

When an existing building is encroaching from a neighboring property, the setback requirements for new structures are applied as if both buildings were located entirely on the same parcel.  Application of setback regulations in this situation is referred to as a “group buildings” scenario in the Tacoma Municipal Code.  As a general rule in the group buildings scenario, the distance separating the existing building from the proposed building in a group building must be at least twice the standard zoning district side yard setback for main dwellings, not accessory buildings.  The only mechanism to reduce the zoning separation requirement is via the variance process.

Example of Required Firewalls

Example of Group Buildings


If a neighbor’s structure is encroaching onto your property, the encroachment is considered a civil matter.  It is recommended that you work with your neighbor to resolve the issue or seek legal advice if you need assistance in a civil matter, as the City of Tacoma cannot provide legal advice.

Options for Properties with Existing Encroachments

  1. Remove the encroachment through a demolition or building alteration. Obtain a demolition permit or building permit.
  2. Install firewalls where necessary for new construction or retrofit existing structures.  Obtain a building permit.
  3. Check with a planner about the feasibility of a zoning variance. Obtain a land use permit.
  4. Relocate the property line. See below.

Relocating a Property Line

If the structure is crossing a property line of which both properties you own, or if the neighboring property owner is willing, it may be possible to remove the encroachment by via a court-ordered Boundary Line Agreement or through a City Process.  If relocation of the property line results in either of the new parcels not meeting minimum zoning regulations in the modification, you will need to consult with a Land Use Planner about the feasibility of the project, and possibly apply for a zoning variance.

Meandering Property Lines Not Permitted

New property lines must be straight and parallel to the right-of-way unless a reasonable variation will give a better arrangement.  New property lines cannot meander across the parcel for the purpose of meeting zoning regulations.

Not Permitted

Not Permitted


Applicable Regulations

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