 The most basic safe room is simply a closet with the hollow-core door replaced with an exterior-grade solid-core door that has a deadbolt and longer hinge screws and strike-plate screws to resist battering.Sometimes, the ceiling is reinforced, or gated, to prevent easy access from the attic or from an overhead crawl space.More expensive safe rooms have walls and a door reinforced with sheets of steel, Kevlar, or bullet-resistant fiberglass.