Housing

Having a home you can feel safe in, no matter what the situation that comes, is important.

Underground
Some choose to build their bunkers under the ground.

Earthen
Building above ground and simply covering your home or community with dirt, can shield you just as well as being under the ground. Its also safer from flooding, and you don't have to worry about tripping on stairs, falling off ladders, or having elevators that might break down. You have the benefit of being able to drive into your garage, instead of leaving your vehicle out in the open. A normal garage door would not be shielded against radiation, so you'd build something thicker to close, or just have the house it connects to protected, and the garage less important. Building above ground means you can have sniper holes to open up and easily shoot trespassing.

Underwater
It is possible to build at the bottom of a lake. You can also do borehole explosions to make a hole, build a home there, and then let it flood.

Tunneled into a mountain
Old abandoned mining shafts are sometimes deep enough to be tapped for geothermal energy, small power plants built there to power your home or community. This is the most reliable source of electricity and thus the most desirable to have. With enough electricity to keep the light bulbs going all the time, you can grow food, medical, and air plants inside.

Regular homes
Although not as interesting, you can build just a regular home, and fortify it against outside threats. You can build a Faraday cage to protect your electronics, and secure it so no air gets in except through your proper air filters. If you fear the world growing colder do to nuclear winter or other causes, then make certain your roof can handle the weight of the snow, and is slanted so the snow slides off. Houses built in areas that currently have an abundance of snow, are already built this way.

Windows
Are there windows large enough for someone to get through? Before the invention of electricity, people had to have large windows for lighting and for cooling their poorly designed homes. There is no reason to have them these days. If building a new home, consider if you need any at all. A small window to look out of and fire a gun out of can be useful at times of course.

Aluminum bars are cheap and easy to install to add some defense to existing windows, however any determined criminal can still find a way through that, it just a delaying method.

Doors
A sledge hammer and a screw driver can easily and quickly knock a door off its hinges. If the criminal has a previous criminal record, which is often the case, then they may have been bodybuilding in prison making them stronger and more dangerous when they get out. Anyone can easily get a drill and quickly get through any lock, including deadbolts.

Walls and fences
Walls and fences are useful at discouraging criminals from entering your yard. Some are easier to cut through than others, and of course ladders can be used to climb over the. Adding barbed wire or rolls of razor wire to the top of a fence can discourage climbers, but these can easily be cut through with cheap and readily available tools. Metal spikes along the top do a better job of keeping people out. With wooden fences, you can hammer nails upward through the top to make spikes that way.

Chicken wire, now called poultry fencing by many vendors, is the cheapest way to secure a yard, and of course keep chickens from getting loose. There is also chain link, wood, concrete, brick, vinyl, and various types of metal fences available.

In addition to discourage invaders, a wall can also hide what you have from others to prevent them from trying to attack you to begin with.

Moat and drawbridge
Electric winches are cheap and can handle 2000 pounds each. Building a drawbridge should be a simple and affordable tasks. As long as your moat or trench is deep and wide enough to matter, criminals are less likely to bother you.

Alligators or other hazards won't work if the invader has a boat and the water is at surface level. If you have proper drainage so the moat only feels half way up, then this makes it more difficult for them, since they'd have to ladder down, cross with a boat, and then stick a long ladder there to climb up again. Looting ladders from fire stations may be done to get the height they need.

You can also feel your moat with something that would sting the eyes of those trying to cross it. Perhaps have an open sewage to keep them from crossing, as long as all homes and active roads are far enough away so not to be bothered by the sight or the smell.

Covering your moat with alcohol and then setting it on fire is a good way to burn those crossing it.

Rows of spikes
Having a bed of nails across your entire yard, would discourage anyone from bothering you. Random height for the sharp metal projectiles should be done, since if all the same size they could easily just lay some boards across it and walk on across.

Animal guardians
You can have domesticated dogs alert you to any intruder, and even aid in defense.

You can also get a species of dogs to raise within your kill zone enclosure, which are territorial animals that will seek out and kill anyone trying to cross over by that area.

You can have bird houses set out since birds will sound an alarm when anyone is approaching.

You can have bee hives setup along a barbed wire fence, so anyone trying to cross it will shake enough to agitate the bees, that will fly out to sting them.