You may not understand why you need this. Did you ever lose luggage on a flight? ...That is covered. Did anyone ever steal from your storage unit? Covered. Ever have a shower leak that damaged someone's apartment or their property? Ever have something stolen out of your car? Lost a piece of jewelry? Had a grease fire? Forgot to shovel and the milkman slipped and fell? Ever had a child ruin a rug? It all goes way beyond just having a fire and having to replace everything you own.
Rental Owners:
Your problems are protecting your real estate and blocking the opportunity to be sued. If all you have is a fire policy you leave yourself short. A true landlord policy addresses the chance of making a mistake while you are doing the job of management. What if someone gets hurt or suffers damaged property because of an eviction? What if the furnace is not maintained properly and someone is injured?
If your building is damaged it is important to have it replaced. You need enough Replacement Cost coverage to be sure of doing that. Some Dwelling Fire policies don't pay to replace the building but only reimburse for the value based on the age and condition of the building.
Look into an umbrella liability policy that will give enough liability protection for your personally owned real estate, residence, and cars all on one policy.