Tenant disputes

[Louise Lapin]

If a tenant in a downstairs apartment is having issues with the tenant in the apartment above them, specifically noise complaints and/or harrassment due to loud noises during the night intentionally to disturb them, whose responsibility is it to intervene when the tenants cannot settle the matter themselves?

The downstairs property is managed by a management company within an apartment complex regulated by an HOA, but the upstairs apartment is owned by a private owner and not managed by the management company (still part of the HOA though).