18.1 What is realistic: the four levels of "bunker"

2 min read

Every shelter relies on five things: mass (for radiation and debris), structural strength (for wind and blast), sealing (for gases and dust), supplies (water, food, sanitation, power), and time (how long you can stay inside). A rented apartment only lets you improve two of them in depth: supplies and sealing. You can add a little mass; the structure, nothing.

What is realistic: the four levels of "bunker"
Level	What it is	Cost and effort	Who it is for
0. Unprepared	Your home or apartment as it is.	Nothing.	Starting point.
1. Prepared shelter room	Interior bathroom or closet with added mass, sealing kit, filter, battery power, water, and sanitation.	Low to medium. No construction. One weekend.	Rented apartment.
2. Tornado safe room	Concrete or steel room designed to the ICC 500 standard and the FEMA P-320 guide, anchored to the foundation.	High. Engineer, permits, contractor.	Owned house.
3. Underground shelter	Underground shelter, or concrete with earth on top, with filtered ventilation and stays of weeks.	Very high. Specialized engineering.	Your own land; uncommon in urban areas.

What each level protects against

What each level protects against
Threat	Level 1: shelter room in an apartment	Level 2: ICC 500 safe room	Level 3: underground shelter
Tornado	Partial. Improves your chances against weak or moderate tornadoes; not against a violent one that levels the building.	High. Designed for winds of 250 mph (400 km/h) and debris impact.	High, if the entrance and the door are designed for it.
Fallout	Low to moderate. Goes from PF 2–3 to somewhat higher, depending on the mass you add.	Moderate to good if the walls and roof are thick concrete (not its design purpose).	Excellent: with 3 feet (90 cm) of earth on top the protection factor reaches the thousands.
Chemical leak	A few hours, sealed with plastic and tape. On the ground floor it is worse than a high floor (see chapter 16).	Same as level 1, unless it has filtered ventilation.	Only if it has filtration designed for gases. An underground shelter can collect heavy gases.
Long blackout	Good, if you have water, batteries, sanitation, and a plan for the heat.	Good; with a permanent generator or home batteries, better.	Depends on ventilation and power.
Riots or intrusion	Moderate: reinforced doors and a room with a lock give you time to call 911.	High: steel door that resists blows.	High.
Flood	None: on the ground floor you must evacuate (see chapter 10).	None if it is in a flood zone; FEMA prohibits placing them in floodways.	Dangerous: an underground shelter can flood.