After a pipe leak in my rental, whose insurance handles the building and whose handles my belongings?

Report the damage to the landlord or manager and your renters insurer, and keep photos and an item list. The landlord's building policy and your renters policy protect different interests: renters coverage generally addresses belongings and may include liability and temporary living expenses, subject to its terms. Do not assume the building's policy replaces your possessions, or that renting automatically makes you responsible for all repairs. Ask who is authorizing building work; responsibility for the loss needs a separate review of the cause, lease and applicable law.