[RickFLM4]

Maybe it's different in Seattle but here in South Florida, this wouldn't even be a question. Debris on your property is your problem regardless of source and honestly I wouldn't even waste my time contacting a property manager for a rental property neighbor.

As far as a record of previous disrepair, I think the avenue there is to notify the municipality (in advance of an issue) and have a record of that notification. The municipality can cite the property owner or step in and correct it and bill them. Your insurance company can't really take corrective action for your neighboring property and they will stuck with a claim whether notified in advance or not.