In both his book Rawles on Retreats and Relocation and in his survivalist novel, Patriots: A Novel of Survival in the Coming Collapse, Rawles describes in great detail retreat groups "upgrading" brick or other masonry houses with steel reinforced window shutters and doors, excavating anti-vehicular ditches, installing warded gate locks, constructing concertina wire obstacles and fougasses, and setting up listening post/observation posts (LP/OPs.) Rawles is a proponent of including a mantrap foyer at survival retreats, an architectural element that he calls a "crushroom".
This type of prepper prides himself on how prepared he is for any apocalyptic event. He finds it hard to keep his mouth shut about his food preparation, water supply, and his self-sustaining environment that he built as a whole. The problem with this is if a disaster does happen, those ill-equipped groups will surely come for these religious preppers first.
Earthquakes, tornadoes, and hurricanes can cause you to leave your home or even be trapped there. Roads could be blocked due to fallen trees, power lines, or even damaged earth from the natural disaster. Rescue crews can not be in all places at once. You may have to wait it out for quite a while before its over. You won't be able to go to the store or to the corner market.