Q: Are renovations performed on detached outbuildings on the property subject to the RRP Rule?

Yes.  EPA interprets target housing to include pre-1978 buildings or structures that are (1) located on the residential portion of the property, and (2) associated with the residential use of...

Yes.  EPA interprets target housing to include pre-1978 buildings or structures that are (1) located on the residential portion of the property, and (2) associated with the residential use of the property.  As a practical matter, the entire property of most urban and suburban residential lots is normally considered to be associated with residential use.  

In the case of real property that is used for nonresidential as well as residential purposes, a judgment should be made as to which part of the property is associated with residential use.  For example, if the structure is in such close proximity that the renovation would pose a risk to those using the property for residential purposes, the structure would be considered associated with the residential use of the property and the RRP Rule would apply.