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".
Survivalism is a movement of individuals or groups (called survivalists or preppers) who actively prepare for emergencies, including possible disruptions in social or political order, on scales from local to international. Survivalism also encompasses preparation for personal emergencies, such as job loss or being stranded in the wild or under adverse weather conditions. The emphasis is on self-reliance, stockpiling supplies, and gaining survival knowledge and skills. Survivalists often acquire emergency medical and self-defense training, stockpile food and water, prepare to become self-sufficient, and build structures such as survival retreats or underground shelters that may help them survive a catastrophe.
These individuals study End Times prophecy and believe that one of various scenarios might occur in their lifetime. While some Christians (and even people of other religions) believe that the Rapture will follow a period of Tribulation, others believe that the Rapture is imminent and will precede the Tribulation ("Pre-Trib Rapture"). There is a wide range of beliefs and attitudes in this group. They run the gamut from pacifist to armed camp, and from having no food stockpiles (leaving their sustenance up to God's providence) to storing decades' worth of food.
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.
This group stresses being able to stay alive for indefinite periods in life-threatening wilderness scenarios, including plane crashes, shipwrecks, and being lost in the woods. Concerns are: thirst, hunger, climate, terrain, health, stress, and fear. The rule of 3 is often emphasized as common practice for wilderness survival. The rule states that a human can survive: 3 minutes without air, 3 hours without shelter, 3 days without water, 3 weeks without food. 
The kind of gear you need – It’s easy to get obsessed with survival gear and start accumulating every new product that comes on the market. If you have money to burn and engage in a variety of backcountry activities this might be a sound strategy. Most people however decide pretty early on what type of outdoor activity floats their particular boat and as such any survival gear should have some sort of relationship to that activity. Everyone, for instance, should have an emergency whistle with them but not everyone will need an extreme sleeping bag. Everyone will need first aid items but not everyone will need to carry croval shovel or a tactical watch or field watch. If you’re a mountaineer you’ll probably want that shovel, especially if you’re climbing in the winter. If you’re going on a day hike and aren’t bringing food that requires preparation there’s no need for a mess kit and so on.
In this review guide we’re going to shine a light on 21 essential pieces of survival gear everyone should seriously consider having in their survival pack. We’re going to concentrate on survival gear aimed at aiding those engaged in outdoor activities and not those forced from their home by natural disaster, although some of these products will also be useful in those types of situations. We’ll start by highlighting 3 pieces of must-have survival gear; those things we would not venture into the wilderness without, and then move on to other valuable survival aids you’ll want to think about packing.