What type of blast resistance should a bunker have?

What type of blast resistance should a bunker have?

The blast resistance a bunker should have depends on the threats you expect — from natural disasters to military-grade explosions. Here’s a detailed breakdown:

  1. Understanding Blast Resistance
  • Blast resistance is usually measured in pounds per square inch (psi) — the pressure a structure can withstand without collapsing.
  • It also considers airborne debris, overpressure duration, and shockwave effects.
  • The thicker and denser the walls, roof, and doors, the higher the blast resistance.
  1. Typical Blast Resistance Levels

Threat Type

Approx. Overpressure (psi)

Bunker Recommendation

Severe Tornado / Hurricane Debris

5–10 psi

Reinforced concrete walls 6–12 inches thick; steel doors; basic anchoring.

Conventional Explosives (home / industrial)

10–50 psi

12–24 inches reinforced concrete or combination concrete + steel; blast doors; earth covering.

Artillery Shell / Large Bomb (~100 lb TNT)

50–100 psi

Thick reinforced concrete walls 2–3 ft thick; heavy blast doors; buried underground; shock-absorbing foundation.

Nuclear Fallout / Military-Grade Bombs

100–500+ psi

Deep underground, multi-foot reinforced concrete and steel; blast doors with overpressure valves; NBC-rated filtration; buried under several meters of earth or rock.

Note: Most civilian bunkers aim for 5–50 psi resistance, enough to survive tornadoes, hurricanes, and small to medium conventional explosives.
Military bunkers or high-security survival shelters go above 100 psi for protection against large-scale attacks.

  1. Key Design Considerations for Blast Resistance
  1. Wall & Roof Thickness:
    • Concrete density matters; 1 ft of reinforced concrete ≈ 10–20 psi resistance depending on reinforcement.
  2. Reinforcement:
    • Steel rebar grids or steel plates embedded in concrete increase structural integrity.
  3. Shape & Orientation:
    • Rounded or angled roofs deflect blast waves better than flat surfaces.
    • Earth-covered roofs provide additional pressure absorption.
  4. Doors & Entrances:
    • Blast-rated doors with pressure seals; avoid large glass openings.
    • Vestibules or angled entryways can dissipate shockwaves.
  5. Depth:
    • Even a few feet of soil above a bunker significantly increases blast protection.
    • Deeper structures = higher overpressure resistance and better fallout shielding.

For most civilian survival bunkers, a practical target is 20–50 psi blast resistance, which protects against severe storms, industrial accidents, and small conventional explosives.