Bunker Systems
Air: filtered, fresh and under positive pressure.
Air is the system a bunker cannot do without. It brings in fresh air, scrubs it of fallout, germs and chemical agents, keeps the inside at a slight positive pressure so nothing leaks in, and carries away the heat and carbon dioxide people produce.
Three tiers
Priced,
installed.
Every Builder bunker includes at least the Essential tier, and larger bunkers require a larger tier. Prices are installed in Utah, including equipment, labor and commissioning, and are confirmed in writing after the site visit.
Essential
$10,500installed
A complete NBC filtration system for a small household.
- 60 cfm NBC unit (American Safe Room Safe Cell class) with HEPA and impregnated carbon
- Two blast valves and an overpressure valve
- 12V battery backup and hand crank
- NDIR carbon dioxide monitor and carbon monoxide alarms
Standard
$17,500installed
More airflow for a larger household, with radon watched continuously.
- 120 cfm NBC unit (Safe Cell ASR-200 or Swiss VA-40 class)
- Blast valves, overpressure valve, hand crank
- Continuous radon monitor plus CO2 and CO alarms
- Steel intake riser, hardened at grade
Premium
$29,500installed
Swiss-built filtration for large shelters and compound quarters.
- Swiss Andair VA-150 class unit: about 88 cfm filtered, 176 cfm fresh air
- Gas filter, blast valves and overpressure valves
- Redundant CO2, CO and radon sensor array
- Feed from the protected battery bank
How we size it
The numbers
behind it.
Fresh air
FEMA's historic minimum is 3 cfm per occupant. Oak Ridge National Laboratory's shelter research found about 1 cfm per person keeps carbon dioxide in check in cool weather, but up to 40 cfm per person is needed in hot weather to carry away body heat.
Filter mode
Under threat, air runs through the NBC filter at a lower rate. That is why heat and humidity are handled by a separate system, sized for full occupancy.
Carbon dioxide
People exhale it continuously. An NDIR sensor with an alarm in every occupied room tells you when to increase airflow.
Radon
Below-grade spaces collect radon. Positive pressure from the blower helps keep soil gas out, and we test every bunker before use.
Questions
About
air.
Do manufactured bunkers include NBC air?
Most leading manufactured bunkers include a basic NBC unit in their base price. That is why every Styrkholm Builder configuration includes at least the Essential air system: a sealed bunker is not safe without one.
What does NBC filtration protect against?
Fallout particles and germs are caught by the HEPA stage, and chemical agents by impregnated carbon. Blast valves protect the system from overpressure, and the overpressure valve keeps the space slightly pressurized so unfiltered air does not leak in.
What happens if the power fails?
Every tier has battery backup and a hand crank. A hand pump alone cannot hold overpressure in anything larger than a closet, so we size the battery to run the blower through an outage.
Prices set 2026-10-28 from published retail equipment prices plus installation. Brand names describe the class of equipment; we may substitute equal or better equipment based on availability. Subscriptions, well drilling and septic systems are quoted separately.
Build it your way.
Pick a bunker, choose each system and see the installed price, then reserve with a deposit.