The biggest building code challenge for most house conversions is that commercial uses are required to be located further from property lines than residential - or a fire wall is required. Most houses in the city will be located on the lot so as to have an issue with one of the side property lines. If the distance is at least 5', alterations required to the wall may be relatively minor. If less than 5', then the wall will likely need to be turned into a fire wall. That would 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, or the adjacent building was constructed with a fire wall along the common property line. 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 over onto an adjacent owner's property.