Storage of combustibles in furnace rooms, electrical rooms and mechanical rooms is not allowed. Fire Departments see situations where wood, cardboard, paper, plastic, clothes, etc., are stored or discarded wherever the people in the building can find room. This includes inside the rooms where sources of ignition are most common. Most often there is no order to these articles and the increased fire load from unnecessary accumulations of combustibles adds to and increases the likelihood of a fire.
If a furnace is in a large open basement where storage is needed, a one hour fire separation can be built around the furnace that includes 2x4 inch stud walls with 5/8 inch Type X sheetrock on both sides of the walls. Proper venting needs to be included, so we insist that the Building Department be involved with approved plans and a building permit before we will accept the separation.
Storage rooms and storage areas need to be kept in an orderly manner, with thought given to need, quantity, order and location. Many people use areas under stairs for storage. This is not allowed as means of egress can not be put in jeopardy in a fire.
Remember that people have a need for storage, so in an effort to accommodate this need, use common sense by using designated areas, limiting the amount, and getting rid of combustibles that are not needed and add unnecessary fire load to the building.