This barn-like structure was apparently once the site of a small eavestrough business. It is a two storey building. Some interesting features include a breaker switchboard, a washroom, and (strangely enough) a kitchenette.
This location is in an active suburban area, so going during the daytime could easily result in being seen by neighbours, shoppers, or drivers.
Update: This building is now boarded up and likely to be demolished in the near future.