Safe Rooms

Planning a safe room in your house or apartment

A safe room provides a protected space that allows multiple people to shelter in place safely isolated from airborne toxins like radioactive fallout or chemical spill vapors, malicious people, and weather events. You can easily create one in your home or office with a Safe Cell NBC filtration system and an assault resistant door.

The Safe Cell is a broad spectrum overpressure air filtration system. It will filter out radioactive fallout, biological toxins, and warfare gasses. It will also create and maintain positive pressure in your safe room, relative to the outside pressure. This is called overpressure. It compensates for any small leaks in your safe room because all the air is flowing outward.


Collective Protection for Civil Defense

A nuclear, biological, and chemical (NBC) safe room protects the occupants from inhaling harmful or deadly airborne toxins such as very fine particles of radioactive fallout, biological toxins, and chemical agents. In the past, the United States Government has poured extensive resources into providing the best information for the protection of its citizens from NBC warfare agents. This is not the case today.

For protection of the U.S. population, the government suggests duct tape and plastic, then wait for further official instruction. Although the tape and plastic method would offer some immediate short term protection from low level toxins at low concentrations, it would be, at best, a short term solution. Most governments tend to only recommend emergency procedures that can be afforded by all their citizens.

As a contrast to most governments, both Switzerland and Israel require, and subsidize the cost of, NBC safe rooms and blast shelters in residential dwellings and commercial buildings. They have strict standards in place governing both the construction of the room and the ventilation equipment protecting the room.


For protection of some of our military personal and government officials, the U.S. Department of the Army – Corps of Engineers has standards by which NBC airborne toxic free areas must comply. These standards dictate the differential pressure (overpressure) in the safe room (protected space) as well as the design of the NBC filter/ventilation system.

The main reasons why an un-pressurized room will not protect the occupants for very long is that the room “breaths.” In other words, it leaks air both in and out through the cracks as the external atmospheric pressure fluctuates – due wind or other atmospheric variables like temperature and barometric pressure swings due to approaching weather fronts. Air constantly tries to normalize its pressure and temperature between different variants As it does this, it brings with it whatever that air contains. Also, in a sealed room, there is no accommodation to replenish oxygen and expel the exhaled carbon dioxide of the occupants.

In order to create and maintain overpressure as well as give the required air exchanges to support the air supply needs of the sheltered occupants, a safe room must be equipped with true positive pressure NBC filtration system and a means of a metering the exhaust air out of the protected space.

The Safe Cell line of filtration systems and their related components are designed and manufactured specifically for this purpose.

The Safe Room

A safe room consists of an envelope (a room) that has a true NBC filtration system installed that will maintain more air pressure inside the room than outside of it (overpressure) in order to constantly keep air blowing outward from the protected space. This will not allow airborne toxins from migrating back into the room and your lungs.

With the right equipment, standard residential construction – homes and apartments – can be a perfectly suitable envelope to keep out airborne toxins. Absolute sealing of the room is not necessary – as long as you have achieved and maintain overpressure.

Even if you are inside a hermetically sealed container, you need true ventilation – air in and air out. This ventilation continually removes moisture, heat, and carbon dioxide that is exhaled by the occupants while bringing in a fresh supply of oxygen-rich air.

This air must be filtered in order to make it safe and breathable. The best filter combination is a bank of pre-filters, an individually DOP scan tested nuclear grade HEPA for radioactive fallout and a nuclear grade carbon adsorber that will adsorb radioactive iodine.

Critical Things to Consider

  • How well the room is sealed – if the room is well sealed, then the air needs some way of being returned from where you get it. An overpressure valve over a penetration (hole in the wall or ceiling) is the best solution.
  • Room size in volume – we like to see at least one air exchange per hour. The 60 CFM Safe Cell will do that in a space up to 3,500 cubic feet. The 120 CFM Safe Cell will do it in up to 7,000 cubic feet.
  • Room selection – inside rooms offer more distance (one component of protection) from radioactive fallout, but outside rooms offer more surveillance of outside your safe room – and you may have visitors. Incorporating a bathroom in a protected space is a good idea, but bathroom fans must be sealed up so you maintain overpressure. If you cannot seal it, place the NBC filter as far away from the bathroom as possible and seal up everything else. The bathroom fan duct will be your air outflow vent.
  • The number of anticipated occupants – the 60 CFM Safe Cell is rated for up to 12 occupants using the ASHRE standard of 5.0 CFM per occupant and 17 occupants using the Israeli standard of 3.5 CFM per occupant. The 120 CFM Safe Cell doubles these occupancy ratings.
  • What pressure the air is that is being drawing into the room – is it being drawn from static air or from a central forced-air system? Static air is best. The airspeed through the carbon be must be engineered to ensure it has the proper residency time in the carbon. Speeding up the air before the filter may reduce this residency time below the quarter-second specification issued by the US Army Corps of Engineers.

Safe Room Components

American Safe Room manufactures all of the critical components you need to outfit your safe room. From high security doors to NBC filters, we have everything you need right here:

Safe Room Doors

We manufacture both ballistic and blast doors

Our ballistic doors features a 3/8 inch thick ballistic plate that gives UL 752, level 8 protection – withstands multiple hits with 7.62 NATO ball. We can scale this up to 50 caliber AP (yes, armor piercing). We’ve made dozens of gun ports that stopped this round cold.

We use the same massive steel hinges with bronze bushings and grease zerks that we use on our blast doors.

They also feature a swinging gun port with an internal cam latch, a wide angle viewer on each side of the gun port, a pry-resistant steel lip around the door leaf, and a steel frame that is welded to the door for easy installation.

We fabricate a square tubing sub-frame that holds the ballistic plate flat so the EPDM seal is evenly compressed. This sub-frame and ballistic plate door leaf are permanently mounted in an steel angle section frame that has a steel anti-pry lip around the door leaf.

Our ballistic doors come in two standard sizes: 32 x 72 inches and 36 x 80 inches – plus any reasonable custom size.
Ballistic doors product page

Our concrete filled blast doors offer outstanding ballistic protection as well as blast and cutting torch resistance.

The steel envelope door leaf is shipped empty. After you mount the door in the rough opening, you fill it with 4,000 PSI concrete. This give you a door leaf that weighs 1,700 pounds. 7.62 NATO ball ammunition makes it about half way through, they are engineered certified for a 50 PSI blast, and cutting torches just need not apply with four inches of concrete fill.

Note the cam latch handles – on both the latch side and the hinge side. Blast doors are made to swing outward so they take the force of the blast in the seated condition. But if someone were to take the time to cut through the massive steel hinges with a torch, they could remove the door and gain entrance. Even if the hinges were cut, the two cam latches on the hinge side will keep the door in place. We also provide wall capture brackets with this option that weld onto the frame and wrap to the inside wall where they are bolted in place. This put six concrete wedge anchors inside your shelter – where they can’t be attacked.

This door also features the deadbolt, wide angle viewer, and differential pressure gauge (not yet mounted) options.
Single leaf concrete filled blast door page

Air filtration and ventilation

Your safe room is only as secure as the air you breath. You need a full spectrum nuclear, biological, and chemical air filtration system in your protected space.

American Safe Room manufactures the Safe Cell line of NBC air filtration systems. The AC and DC Safe Cells are the only NBC air filters available that features an onboard battery backup system that automatically switches to a user supplied battery if the grid goes down – maintaining overpressure in your safe room.

The Safe Cell product pages:

  1. 60 CFM – DC only filtration system (12 people)
  2. 60 CFM – AC and DC filtration system (12 people)
  3. 60 CFM – AC and DC complete system (12 people)
  4. 120 CFM – AC and DC filtration system (24 people)
  5. 120 CFM – AC and DC complete system (24 people)

Blast valves

Blast valves are heavy steel pressure vessels that mount over the ventilation pipes in a safe room. They close if a detonation occurs nearby, then re-open to allow the NBC air filtration system to keep providing airflow.

Our blast valves shut automatically for both pressure and vacuum. They feature lightweight valves that have an extremely fast closing time. When an detonation occurs, the atmosphere is blown outward, leaving a near-vacuum void. This void expands outward until the mass of the atmosphere overcomes it. If you’ve ever seen footage of trees blowing one way, then the other after a detonation, that’s the first two phases of a blast – positive and negative pressure. You need double acting automatic blast valves in your safe room.

Our blast valves also have a manual lock shut function. This is in case there is a structural fire outside your safe room or a malicious person dumping fuel down your vent pipes. Structural fires have a thermal element (heat) and produce massive amounts of carbon dioxide. If you are trapped in your safe room during a fire, turn off the Safe Cell and lock the blast valves shut for a few hours.
Blast valve product page

Overpressure valves

These are one way check valves that mount on the outflow blast valve. We manufacture both  and adjustable overpressure valves.

They only let air out so if there is a wind gust outside your safe room, unfiltered air can’t back up in through the outflow pipe. They also give a slight resistance to the airflow so the Safe Cell has something to push against. This helps create and maintain overpressure in the protected space.
Preset overpressure valve product page
Adjustable overpressure valve product page

Automatic ventilation blower

This is a small blower that puts out nearly as much airflow as the Safe Cell to provide ventilation (not filtration) in your shelter. It mounts beside the Safe Cell and the same flexible air intake hose is slip fit onto the bottom of this blower. There’s not a scenario where you will need both the Safe Cell and the automatic blower at the same time – you either need air filtration very badly or you don’t.

It also comes with an automatic timer so you can set it to come on every day and freshen the air and relieve the condensation in your safe room.
Automatic ventilation blower product page

Ventilation pipes

We fabricate steel ventilation pipes to order. They bolt on to the outside of a safe room with concrete wedge anchors and a gasket. The top end features a rain hood with an insect screen inside of it held on with a security fastener.

To get proper ventilation, you need to bring air in, filter it, then return it from where you took it. The best place to take it from is outside – where there is a never-ending supply of oxygen.

The intake should be mounted on the opposite corner or wall from the outflow so the filtered air has to transit the entire shelter before it’s kicked back out. This will help remove the carbon dioxide and moisture the occupants exhale.
Ventilation pipe product page

Backup hand crank

For long term power outages, you need a way of replenishing the oxygen in your safe room that is sustainable without electricity.

We manufacture a geared hand crank that will draw 60 CFM of air through the Safe Cell. It mounts at a comfortable height and is easy to operate.
Backup hand crank product page

Replacement air filters

Every safe room should have a reload of filters. The Safe Cell has a unique and very safe filter replacement protocol.  Due to its lightweight construction and how easy it dismounts from the wall, the entire unit is taken outside, the filters replaced, it’s sealed back up and brought back in. The old filters are left outside.
Replacement filters product page

Differential pressure gauge

Know you have positive pressure (overpressure) in your safe room. This gauge give you a continuous reading of the difference in pressure between the protected space and the outside.
Differential pressure gauge product page

Double leaf doors

Need a bigger door? Check out our double leaf doors. Standard sizes go up to 96 inches wide.

These are two doors mounted in one frame. They allow vehicles and equipment to be moved into garages and shops and feature the same massive hinges and secure cam latches of our single leaf doors.
Double leaf concrete filled blast door product page

For more information, please contact our sales department