An expert

In civil defense shelters

Anfra provides all services related to the construction, design and equipping of S1 class shelters. The best way to ensure a smooth and cost-effective project is to involve us at the design stage. Building and equipping shelters is a highly regulated activity, and we are the experts in the field.

We implement efficiently

up to 10% from the Finnish civil defense shelters

As an experienced shelter construction specialist, we are able to act quickly. Our castings are ready in as little as five working days.

We have been building shelters since 2015 and are currently building around 10% of Finland's shelters. We are also aware of the differences in interpretation of requirements from one location to another, as we have built shelters for dozens of locations.

Our services also include equipping the shelter, measuring the tightness of the shelter and the inspection report.
We are happy to help our clients with the construction solutions and the bureaucracy involved in building shelters. Therefore, it is a cost-effective option for the builder to involve Anfra at the design stage.

For our annual contract customers, we have provided precise price lists for the implementation of civil protection, regardless of the location and purpose. Our expertise in the construction of civil engineering shelters can also be applied to other concrete construction projects. Our installers are also experienced in the construction of other concrete bunkers. For example, a watertight sprinkler basin can easily be constructed using the same technology.

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When building shelters, Anfra always recommends ordering a complete package from the same contractor, as this is usually the easiest and most cost-effective solution for the client. 

Concrete Structure Plans

Structural design and calculation of shelters with the quality and confidence of experience.

Concrete structures in cast-in-place

Foundations, floors, walls, vault and slab in situ.

Castings and layout drawing

Ventilation ducts and other penetrations, doors and hatches in public shelters.

Post-delivery package

The after-sales package includes the installation of the statutory crisis equipment and fittings, as well as a leakage measurement.


There are many advantages to implementing a population protection system in the form of Anfra's fixed cast. In one package, you get cost-effectiveness, efficient structural design, execution of all structures from the foundations upwards, and castings with placement drawings. In addition, we equip the shelter up to the completion.

On-site casting makes it easier to coordinate and schedule work according to the needs of the site. Concreting of the exterior walls, vault and slab is carried out in one batch, ensuring seamless and leak-proof structures. Our foreman takes care of all orders and work organisation.

Working steps

Design experience of more than 100 S1 class civil protection systems. We provide cost-effective design that saves both the client and the environment.

The most cost-effective method is to use a reinforced floor slab as a foundation, if the ground allows. Our installers will form, reinforce and concrete the floor. We also coordinate the customer's drainage and other plumbing work with the installation work. The floor is usually poured on the day the work starts.
The day after floor casting, we start wall and vault moulding, casting installation and reinforcement. After the wall reinforcement, the wall moulds are doubled and the moulds are fitted with handrails and a walkway for the vaulting work. If reinforcement inspections are required, we will schedule them as soon as the work starts. If the vault needs fasteners for bolt groups or similar structures, they will be installed in place during the moulding and reinforcement work, accurately dimensioned.

Once the formwork is fully completed and reinforced, concreting begins. Concreting is carried out at the same time for the outer walls, vault and slump floor. This working method has been proven to work irrespective of the season, with hundreds of shelters in operation.

After concreting, we quickly dismantle the external moulds so that other construction work on the site can continue. In cold weather, we use fans, concrete curing cables and good weather protection to maintain heat. The concrete hardening reaction also generates heat and the day after the pour, the shelter is tropical, even if it's freezing outside. The mould breaking strength of the vault is always verified by a separate concrete thermal monitoring.
When the work is finished, we clean up the sites, grind the moulded seams and hand over the site to the client. Concreting protocols and other necessary documents are also naturally included in the scope of delivery.




The water-tightness of the structures is ensured, as there are no soldered joints (in some sites, prefabricated structures are even prohibited to ensure water-tightness).


At best, we can have the shelter in place in 4 working days, usually in about 1-3 weeks.

Wide editorial content

If required, we can also carry out all other concrete structures on the site, including structural design.

Precise pricing

In prefabricated shelters, the foundations and flooring are more challenging due to the prefabrication technique and are usually left to the client. Therefore, when comparing prices, care should be taken to ensure that the construction costs of a prefabricated shelter are correctly calculated. We will be happy to help you make a comparison.



Shelters are built to protect people from disasters. It is therefore important that they are professionally built. The obligation to build a shelter is determined by the size of the building, its intended use and the number of people in it.

Facts about shelters

The construction of public shelters is regulated by laws and regulations, but at local level, construction and planning is guided and supervised by regional rescue services and municipal building control authorities. It is important to always consult local authorities first when building (SPEK, 2016).

(Rescue Act 379/2011, SPEK, 2016)

- The obligation to build a public shelter arises when the floor area of a group of buildings for living, working or staying is at least 1200 m2. For industrial, production, storage and assembly buildings, the obligation to build a civil protection system arises when the floor area is at least 1500 m2. The Rescue Act lists exceptions to the above limits.

- The actual protection space of a public shelter must always be at least 20 m2. However, the shelter itself does not include the barrier room or tent, or the technical rooms (engine rooms and control room), for which additional space must always be provided. In practice, the smallest shelter that can be built is 24 m2 (protected area 20 m2 , flysheet 2,5 m2 and 1 IV installation 1,5 m2)

- The wall and vault shall be at least 300 mm of strong reinforced concrete. The shelter floors shall have a minimum structural thickness of 150 mm. The room height shall be at least 2300 mm.

- A water point is not mandatory inside the shelter, but it must be located in the immediate vicinity of the shelter (some exceptions exist).

- The most cost-effective structural solutions can be achieved by using the theory of yield stress in strength calculations.

The shelter may be in peacetime use, but must be able to be taken into shelter use within 72 hours. In order to ensure the functionality of the shelter equipment, shelters must be inspected and maintained every 10 years (Decree 506/2011).

In schools, kindergartens and service homes, shelters are often used as social, laundry and storage facilities, sometimes even as teaching facilities. In hotel and sports facility projects, shelters are often used as gyms, changing rooms or equipment storage. In residential projects, by far the most common peacetime use is for apartment-specific cage storage. Civilian shelters that are not used at all in peacetime are already rare. In everyday language, many people refer to these facilities as bomb shelters.

Finland has been preparing for systematic protection of people and property in crisis situations since 1958. Preparedness has been made by building modern civil defence shelters and functional shelters during normal circumstances. (PESK, 2016)

The shelters built today provide protection against radiation, toxic substances, collapses and the effects of weapons. Biological and chemical warfare agents are also well filtered by the filter material of modern filters. (Population Protection, HelsinkiTurva 2019)


  • Design and construction of an S1-class civil protection shelter, Finnish Rescue Services Association (SPEK), 2016
  • Rescue Act 379/29.4.2011, read 13.5.2019
  • Decree of the Ministry of the Interior on the technical requirements for civil defence shelters and maintenance of civil defence shelter equipment 506/2011 10.5.2011, read 13.5.2019
  • Design Guidelines for Public Shelters, 2006, City of Oulu Building Control, created 13.5.2019
  • Population protection, HelsinkiTurva 2018, City of Helsinki, created 13.5.2019
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