How the existing house sits on the property can make adding commercial use a challenge. The building code requires that a commercial use be located further from property lines than is allowed for a residential use. Most houses in the city are so close to one or both side property lines that the existing walls may need to be turned into fire walls. If the distance between a wall and the property line is at least 5', alterations required to the wall may be relatively minor. If the distance is less than 5', then that could mean:
- eliminating any window, vent or similar openings
- applying a single layer of 5/8" gypsum board to the inside surface of the exterior wall
- removing the siding at that portion of the exterior wall, applying gypsum board to the exterior surface, then replacing the siding
In design zones, these this type of exterior work could trigger the requirement for design review.
Sometimes a house is close to a property line that abuts a commercial parking lot. In unusual circumstances such as these, you may be able to appeal the fire wall requirement.
As a part of the change of occupancy process, the city will ask you to include a site plan that shows the location of the house in relationship to the property lines. The actual location of lines separating privately owned lots from each other is not always easy to find. Looking in Portland Maps is a good starting point, but Portland Maps can't give you dimensional distances between a building and its adjacent property lines. It doesn't always accurately show how a house sits on the lot. Occasionally, there is an old surveying marker somewhere along the line, or a brass marker in the sidewalk. Only an actual survey may be able to accurately locate the property line.
Sometimes a building actually straddles the property line, sitting partway on the neighbor's property. That may be the case even when, "out in the real world", there appears to be several feet between the building and what looks like the property line. Please be aware that we cannot legal issue a change of occupancy permit for a building that actually extends onto an adjacent owner's property.