Firearms instructor and survivalist Colonel Jeff Cooper wrote on hardening retreats against small arms fire. In an article titled "Notes on Tactical Residential Architecture" in Issue #30 of P.S. Letter (April 1982), Cooper suggested using the "Vauban Principle", whereby projecting bastion corners would prevent miscreants from being able to approach a retreat's exterior walls in any blind spots. Corners with this simplified implementation of a Vauban Star are now called "Cooper Corners" by James Wesley Rawles, in honor of Jeff Cooper. Depending on the size of the group needing shelter, design elements of traditional European castle architecture, as well as Chinese Fujian Tulou and Mexican walled courtyard houses, have been suggested for survival retreats.
Tools may include cutting tools such as saws, axes and hatchets; mechanical advantage aids such as a pry bar or wrecking bar, ropes, pulleys, or a 'come-a-long" hand-operated winch; construction tools such as pliers, chisels, a hammer, screwdrivers, a hand-operated twist drill, vise grip pliers, glue, nails, nuts, bolts, and screws; mechanical repair tools such as an arc welder, an oxy-acetylene torch, a propane torch with a spark lighter, a solder iron and flux, wrench set, a nut driver, a tap and die set, a socket set, and a fire extinguisher. As well, some survivalists bring barterable items such as fishing line, liquid soap, insect repellent, light bulbs, can openers, extra fuels, motor oil, and ammunition.
The term "survival kit" may also refer to the larger, portable survival kits prepared by survivalists, called "bug-out bags" (BOBs), "Personal Emergency Relocation Kits" (PERKs) or "get out of Dodge" (GOOD) kits, which are packed into backpacks, or even duffel bags. These kits are designed specifically to be more easily carried by the individual in case alternate forms of transportation are unavailable or impossible to use.
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.