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FAQ – FORORAK Modular Shelters, Equipment and MDS Upgrades

Below we have compiled answers to the questions most frequently asked by individual and institutional clients regarding FORORAK steel modular shelters, as well as upgrades of existing facilities and the adaptation of basements or underground garages into Temporary Shelter Places (MDS). We prepared this material to be as specific as possible — so that key issues related to design, installation, protection level, systems (NBC/CBRN, power supply, fire protection, sanitary facilities), as well as operation and servicing, can be clarified quickly.

1. How are FORORAK steel shelter modules constructed?

FORORAK steel modules are manufactured from high-grade steel and feature full ribbing and structural reinforcements.
This solution provides high rigidity and load-bearing capacity when covered with soil, as well as resistance to dynamic loads, such as blast shock waves.

Each segment is designed for long-term underground use. The steel is protected against corrosion, ensuring durability for many years.
In addition, the modules have standard transport-friendly dimensions (typically 6 to 15 m in length, approx. 2.5–3 m in width, and an internal height of approx. 2.5 m) and can be modified for specific intended use.

Yes.

FORORAK modular shelters are designed as a scalable system, meaning multiple prefabricated modules can be combined into one integrated structure. Individual segments can be connected in various configurations—from linear (in series), through branched layouts (e.g., rooms branching off a main corridor), to ring (closed-loop) configurations.

This allows the creation of a facility tailored to specific needs: from a small family shelter to an expanded collective shelter with corridors and multiple rooms (e.g., sleeping areas, storage, technical sections), etc.
All modules are designed to fit together easily and to enable expansion of installations between them (ventilation, power, communications).

Installation begins with preparing the excavation and pouring a reinforced concrete base slab.

Next, the module is anchored to the slab, stabilizing the structure in the ground and preventing movement (e.g., due to shocks or ground settlement).
After installing the module and all connections and equipment, the entire structure is backfilled with layers of soil.

If necessary, drainage layers are installed around the shelter to divert water.
Finally, the land is restored to its original condition—grass can be sown, vegetation planted, or a driveway/parking area arranged above the shelter.

Once backfilled, the shelter is completely concealed underground, invisible from the outside, while still providing a high level of safety and comfort inside.

Protection against water and moisture is crucial in underground shelters. The shelter design includes several layers of flood protection:

  • Structural insulation: the steel module has anti-corrosion protection and waterproofing on its surface, and an optional external concrete jacket additionally protects against water penetration. The foundation (reinforced concrete slab) is also insulated to prevent groundwater ingress from below.

  • External drainage: during installation, a drainage system is built around the shelter. Layers of gravel, sand, and geotextile are used, along with perimeter drainage, to route groundwater away from the shelter walls. As a result, rainwater and groundwater have limited access to the structure, flow into the drainage system, and then to soakaways or discharge pipes.

  • Drainage (filter) layers: above and around the shelter, drainage layers (e.g., sand) are placed to facilitate water runoff into deeper soil and to prevent waterlogged areas directly above the shelter roof.

Thanks to these solutions, the shelter is protected against both groundwater and flooding caused by precipitation.
The structure is designed to be watertight; a typical shelter meets standards similar to underground tanks, meaning no leaks.

Yes — additional reinforcement is possible through the use of a concrete jacket.

This involves installing reinforcement (rebar, meshes) around the external walls of the steel module and pouring a layer of high-strength concrete.
This steel-and-concrete “sandwich” acts as armor: a steel load-bearing core is surrounded by a reinforced concrete shield.

This significantly increases resistance to factors such as blast shock waves, fragments, and ballistic projectiles, and also improves long-term durability (reinforced concrete additionally protects steel from corrosion).
After concreting, the module is backfilled with soil like a standard shelter, and the overall protection level increases.

FORORAK modular shelters provide a high level of protection against the effects of conventional explosions.
Simply installing the shelter underground significantly increases safety—the surrounding soil acts as a natural absorber of shock waves and fragments.

The steel module structure is designed to withstand substantial dynamic overloads from explosions. Ribbing and reinforcements give the walls and roof high resistance to rapidly rising pressure (as in a blast wave).

A standard steel modular shelter can withstand a blast wave caused, for example, by a conventional bomb or artillery shell detonating at a certain distance; the structure will not collapse, and internal systems (e.g., blast valves) protect the interior against sudden pressure surges.

If the external reinforced concrete jacket mentioned above is used, blast resistance increases significantly.
The reinforced concrete armor can stop fragments from bombs or shells that, with a steel-only structure, could cause denting or even perforation of the wall.

Protection levels can be adapted to requirements. For strategic facilities, it is possible to design a shelter meeting stringent Category A standards (enhanced resistance), capable of withstanding a very close blast wave on the order of >0.1 MPa and extreme fragment and overpressure loads.

In summary, the FORORAK shelter protects against typical wartime threats—blast shock waves, bomb and shell fragments—and, in reinforced variants, also against the direct effects of explosions at close range.

Yes.

The modular shelter structure is designed with a significant safety margin for static soil loads.
Once backfilled, the shelter must carry the weight of several meters of soil, groundwater, and even surface loads (vehicles, buildings, etc.), so the steel walls and roof have appropriate thickness and ribbing.

Strength tests and building standards require the structure to withstand soil pressure with a substantial reserve, meaning that even in unusual situations (e.g., very high load over a small surface area above the shelter), structural integrity is maintained.

In addition, the shelter foundation is integrated with the module through an anchoring system to the reinforced concrete slab, preventing shifting or uplift under ground forces.

As for tectonic movement or shocks (e.g., due to an explosion or earthquake), the flexibility of steel is an advantage—steel can elastically deform within a certain range and absorb energy without cracking like brittle concrete.

FORORAK shelters are designed to operate under shock and seismic conditions; elements are properly reinforced and connected so the structure is monolithic and resistant to ground deformation. Anchoring to the reinforced slab allows transfer of horizontal loads, so even with ground settlement or displacement, the facility remains stable.

In practice, this means the shelter will not collapse or crack even under significant ground movement. Long service life in an underground environment is accounted for already at the design stage.

FORORAK shelters are equipped with complete NBC filtration and ventilation systems that provide breathable air and protection against contamination.
The system draws outside air through a ventilation unit equipped with specialized filters, treats it, and supplies it into the shelter.

An overpressure of approx. 50–250 Pa is maintained.
The installation also includes safety (blast) valves, which protect the ventilation system and the shelter interior from blast wave effects and sudden pressure surges at the air intake in the event of an external explosion.

In normal mode, air is filtered through a pre-filter (captures dust, pollen, aerosols) and—during an NBC threat—through an NBC filter-absorber that removes toxic chemical warfare agents, radioactive particles, and pathogens.

The treated, clean air is delivered to the rooms, ensuring safe breathing conditions even in a chemically, biologically, or radiologically contaminated environment.

The entire system is airtight. The shelter has sealed closures, gas-tight and watertight doors, and with maintained overpressure it provides full isolation from external factors.

The NBC protection system used in modular shelters protects against the full spectrum of CBRN contamination threats.
NBC filters remove chemical warfare agents (gases and aerosols), biological agents (e.g., bacteria, viruses, spores), and radioactive dust and fallout from the intake air.

Additionally, the system captures toxic combustion products (smoke, oxides) that may occur as a result of fires or explosions.

Thanks to sealing and maintained internal overpressure, the shelter also protects against the ingress of industrial gases or external smoke contamination.

In other words, people inside are protected against the effects of chemical and biological attacks, toxic substance leaks, and ionizing radiation from radioactive fallout (by filtering radioactive particles).
The NBC system therefore allows occupants to safely wait out outside contamination while maintaining clean and healthy air inside the shelter for the duration of the threat.

NBC systems used by FORORAK include safeguards in case of power outage.
The ventilation unit has a dual operating mode: electric (normal) and manual hand-crank operation.

This means that even in a complete loss of power, the fan can be driven manually and fresh air can still be supplied to the shelter.
In addition, installations can be connected to an emergency power source (e.g., batteries/accumulators or a generator), which provides power for lighting and filtration/ventilation devices during outages.

The LUNOR NBC system itself is designed for continuous operation for many days or even weeks without interruption; it is highly reliable and capable of working in emergency mode without loss of filtration efficiency or pressure maintenance.

This means that even in a prolonged crisis, shelter users will have ventilation and protection against contamination.

Yes.

The shelter can be equipped with a complete electrical system with emergency power capability.
As standard, the facility is connected to the electrical grid to provide everyday lighting and power for devices.

At the same time, backup power systems are installed, most commonly batteries/accumulators and a generator.
In the event of a grid power loss, the system automatically switches to battery or generator power, maintaining operation of lighting and critical systems (ventilation, communications).

Interior lighting is LED-based (energy-efficient) and includes both main room lighting and emergency lamps that switch on automatically when primary power is lost.
As a result, even in an emergency, the shelter interior remains illuminated and functional. All electrical components are designed to operate safely in enclosed conditions.

A modular shelter made of steel and concrete is inherently non-combustible; the structure withstands high temperatures and does not fuel a fire.
However, because of internal equipment and materials (e.g., furniture, textiles, electrical devices), additional fire protection measures are used.

Each shelter can be equipped with a fire detection system (smoke detectors, fire alarm system) and an alarm that immediately signals the detection of fire.

FORORAK also offers automatic extinguishing systems tailored to shelter spaces. Depending on needs, these may include water mist systems (e.g., Aquatech systems) or gaseous suppression systems (e.g., using Novec™ 1230).

Water mist systems generate microscopic droplets that turn into steam and locally displace oxygen at the fire source—suppressing flames without consuming all oxygen in the room, allowing people to breathe.

Modern agents such as Novec are non-conductive, do not damage electrical equipment, leave no soot or residue after discharge, and are highly effective at extinguishing fires.

All these fire protection systems can operate automatically immediately after detection, suppressing a fire at an early stage.
This minimizes the risk of fire spread inside the shelter and limits potential damage.

Yes.

Fire suppression systems selected for shelters are designed to be safe for people in enclosed spaces.
Water mist does not threaten breathing (it removes oxygen only in the immediate vicinity of the flames) while absorbing heat and quickly reducing fire temperature, preventing burns and structural damage.

Clean agents such as Novec 1230 are also non-toxic to humans at extinguishing concentrations and leave no damage after discharge—they do not cause corrosion, do not contaminate equipment, and evaporate rapidly.

After activation, it is sufficient to ventilate the shelter (ensured by the ventilation system) to return to a safe environment.
This allows users to quickly resume normal operation inside, and the shelter does not require complex cleaning after a fire.

Yes.

The shelter can be equipped with full sanitary facilities. The standard scope includes installation of a WC (toilet) and a washbasin to meet basic hygiene needs.

The toilet typically operates as a chemical toilet or is connected to a sealed waste tank (cesspit), or to a local sewer system if available.

Drinking and utility water can be stored in dedicated tanks inside the shelter. Typically, a water tank of appropriate capacity is installed (depending on expected stay duration and number of occupants), along with pumps or pressure systems (hydrophore units) to distribute water to taps.

The water circuit is closed and protected against contamination — drinking water is stored under conditions that prevent pollution.

Wastewater and greywater from the washbasin or shower (if included) go to a wastewater tank equipped with a pump and check valves to prevent backflow.
After the threat has passed, the accumulated wastewater can be pumped out (e.g., to a cesspit or by a septic service).

The entire sanitary system is designed to function even when cut off from public utilities — for example, water pressure can be provided by a hydrophore powered by an electric pump (with emergency power), and the shelter ventilation system removes odors.

In addition, the interior is equipped with elements that facilitate longer stays, such as water tanks, long-life food supplies, a dedicated area for meal preparation, and sleeping/resting spaces.
All of this makes it possible to function for a certain period in relative comfort, even while isolated from the outside world.

Yes.

FORORAK delivers independent water intake solutions for modular shelters as an element that increases autonomy and safety.
As part of a project, we can design and build an autonomous water intake (e.g., a drilled/deep well) intended to supply the shelter with drinking and utility water independently of the municipal water network.

Depending on local ground and water conditions and client requirements, the system may include:

  • intake (drilled/deep well) and the installation bringing water to the shelter,

  • buffer tank and water reserve,

  • filtration and treatment system (e.g., mechanical filter, carbon filter, UV disinfection),

  • hydrophore / pump,

  • emergency power supply for pumps (generator / batteries),

so the system also works during power outages.

An independent water intake increases the shelter’s self-sufficiency, ensures access to water during supply interruptions or infrastructure failures, supports long-term shelter operation (sanitation, hygiene, drinking water), and is especially recommended for high-autonomy private shelters as well as corporate and institutional facilities.

Yes.

Each water intake is selected individually based on local soil and groundwater conditions, drilling feasibility, the expected number of users and autonomy time, and water demand (drinking/sanitary/technical).

Yes.

A shelter can be equipped with various communication systems that enable contact with the outside even when the facility is closed and isolated.

Already at the design stage, telecommunication penetrations are planned—special cable penetrations with hermetic seals allow wiring (telephone, internet, antenna lines) to be brought into the shelter without compromising tightness. This enables installation of a landline phone, internet connection, or CB radio connected to the outside via cables.

In addition, external antennas (radio, TV, satellite communications) are often installed on the surface and connected to the shelter via coaxial cable or fiber through a hermetic penetration.

Inside, users can operate radios, TV receivers, or even internet—provided external infrastructure is still functioning or independent communication means are available.

For safety, internal communication systems can also be installed, such as intercoms between shelter rooms and at entrances (facilitating contact with the person at the hatch). Monitoring systems such as cameras may also be added.

In emergency situations, users may also rely on portable communication means such as mobile phones (if signal reaches—often with an antenna GSM signal booster) or walkie-talkies.

In summary, the shelter does not cut users off from information. With appropriate equipment, it is possible to remain in contact with the outside world and emergency services, and to monitor the surroundings while staying safely inside.

On a daily basis, a private shelter does not have to sit unused — many owners use it as an additional cellar, long-term food storage, or even a dedicated hobby room.
However, it is important to keep the shelter in a state of readiness for use.

This means equipment and systems should be operational and the interior should be kept orderly so people can enter quickly. It is recommended to store drinking water, long-life food supplies, a first-aid kit, and other crisis essentials in the shelter.

The manufacturer provides full documentation and operating instructions, including guidance on starting systems (e.g., NBC filtration/ventilation, generator), using communications equipment, and periodically checking parameters.

In the event of a threat (contamination alert, attack, or natural disaster), the procedure is as follows:

  • everyone goes to the shelter,

  • hatches/airtight doors are sealed shut behind them,

  • life-support systems are activated (if required; NBC filtration is turned on when needed).

FORORAK shelters are designed for simple operation even under stress; most systems work automatically or with a few switches. For example, after closing the hatch it is sufficient to switch on emergency power, and the ventilation system maintains overpressure and filtration automatically.

During the stay, users should follow recommendations for conserving supplies and energy (e.g., rationing food, turning off unnecessary lights). Thanks to a well-designed interior layout, ventilation maintaining air freshness, and efficient lighting, comfort is high enough for many hours or multiple days underground without severe discomfort.

After the threat has passed, it is sufficient to ventilate the space (opening valves and hatches once outside air is safe), and the shelter can return to standby mode.

Shelter capacity depends on its size and layout, but even a basic family module can provide safe shelter for several people.

In design, minimum floor area and volume per person are typically assumed in line with civil defense standards — about 1 m² of floor area and 2.3 m³ of volume per person are values that enable longer stays.

FORORAK modules are available in various sizes (length from approx. 6 m upward), translating into usable floor areas from several to several dozen square meters per module.

For example, a 6 m module with a width of 2.5 m provides approx. 15 m² of floor area, which can comfortably accommodate 5–6 people along with equipment and supplies.

Larger configurations combining several modules can accommodate dozens of people—projects for 50 people or more are also implemented in modular layouts (with multiple sleeping rooms, sanitary facilities, etc.).

It is important that the number of occupants does not exceed the design assumptions; then the ventilation system provides adequate air exchange for everyone, and supplies and equipment are sufficient.

In an emergency, the shelter can accommodate more people than the optimal design, but at the expense of comfort. Therefore, when planning a shelter, it is advisable to include a margin—for example, for a family of 4, designing for 6–8 people.

In summary, a FORORAK modular shelter can be a compact family refuge or a large bunker capable of protecting a bigger group—it all depends on the module configuration.

The length of autonomous stay depends primarily on supplies and the capacity of life-support systems.

The shelter systems (ventilation, emergency power, sanitary facilities) are designed for long continuous operation — for example, the filtration/ventilation system can operate continuously for many days, a generator with sufficient fuel can run for dozens of hours, and sanitary systems with large tanks can handle wastewater for many days.

Air supply is not a limiting factor because the system continuously filters and delivers fresh outside air.

The limiting factors are food and water supplies and occupants’ psychological comfort. With typical provisions (e.g., 2 liters of water per person per day and 2,000 kcal per person per day), it is possible to safely remain in the shelter for at least 2 weeks—and often longer if resources are rationed.

FORORAK recommends planning for a minimum of 14 days of shelter autonomy. In practice, many private shelters are stocked for 30–60 days, especially with freeze-dried food and bottled water or tank reserves.

Living conditions (temperature, humidity) are maintained within acceptable ranges by ventilation; air exchange prevents excessive humidity and CO₂ build-up, and the surrounding soil stabilizes temperature (underground typically 8–12°C, warmed by people and equipment to a comfortable 18–20°C). LED lighting and electronics can be battery-powered for extended periods.

From a technical standpoint, staying for a month or longer is possible. The human factor is crucial, however — limited space and stress can affect wellbeing. Therefore, shelters may include sleeping areas and amenities such as books/games and radio communications to support more normal functioning.

In summary, shelter autonomy is at least several days to two weeks, and with proper provisioning can extend to several months. It is recommended to leave the shelter as soon as the threat has ended, provided outside conditions allow.

A modular shelter, despite its robust design, requires periodic inspections like any technical facility. Fortunately, these are relatively straightforward and not very frequent.

We recommend performing an inspection of all shelter systems at least every 6 months. Such an inspection includes checking the condition of door and hatch seals (airtightness), testing the NBC ventilation system (short run and filter check), inspecting the electrical system (backup power and lighting test), servicing the generator (oil change; a monthly test start is recommended, with approx. 1 hour of operation), and checking the sanitary system (e.g., emptying/cleaning the wastewater tank).

NBC filters typically have a long shelf life (often many years when sealed), but once opened they should be replaced according to instructions.
Battery/accumulator packs should also be replaced every few years to maintain full capacity.

All these tasks can be performed by the owner following the provided instructions; however, FORORAK also offers professional service and maintenance. This ensures the shelter is checked properly and worn parts (e.g., seals) are replaced.

The manufacturer also provides support for future upgrades (e.g., replacing filtration equipment after many years, expanding the electrical system, etc.). Overall, a well-maintained shelter can operate reliably for decades. The key is not to neglect periodic checks—just as with heating equipment or a car — for user safety.

FORORAK provides a warranty for the shelters it builds and all systems installed within them. Detailed warranty terms are defined in the contract with the client; however, a multi-year protection period can typically be expected.

The steel structure is designed for decades of use. If a concrete jacket is applied, service life increases further (concrete protects steel against corrosion). The manufacturer ensures all components meet high quality standards, translating into long-term reliability.

Swiss-made LUNOR NBC filtration/ventilation systems are also designed for decades of operation and high reliability. In practice, they maintain protective parameters over a long period, and servicing is generally limited to filter replacement and seal maintenance.

Equipment such as filters, ventilation units, and generators is covered by the respective manufacturers’ warranties. FORORAK provides both warranty support and post-warranty service, so even after warranty expiry the client can receive assistance with inspections, repairs, and upgrades.

In short, the shelter is a long-term investment, and the warranty is intended to provide peace of mind in the initial years of operation and confirm build quality.

Yes.

The ability to expand is one of the key advantages of the FORORAK modular system. If a small shelter is built initially but future expansion is anticipated, it should be discussed with the manufacturer at the design stage.

The structure can be prepared for adding new segments (e.g., leaving sealed openings that can be opened later). The system is scalable — additional prefabricated modules can be attached to create a larger arrangement of rooms and corridors.

Expansion involves excavating the selected wall, adding another module (on its own foundation), and creating a tight connection between the existing and new segment. This is technically feasible, although it requires additional earthworks.

Therefore, if a larger complex is planned from the outset, it is often cheaper and simpler to build a larger module layout immediately rather than in phases. Nevertheless, FORORAK keeps the option of future expansion open.

Retrofitting an existing shelter with new systems is also straightforward — for example, additional communication systems can be installed, filtration systems replaced or supplemented, and new devices added. The universal design allows the shelter to evolve with user needs.

Do you have additional questions or
want to match a configuration to your property?

Contact us — we will advise on the solution, prepare initial technical assumptions, and propose an equipment variant tailored to the desired level of protection and autonomy.

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