The pitfalls of installing fire resistant

Not because of unwillingness, but because of, for example, different interpretations of standards or incorrect product information, the fire resistance of, for example, hollow walls is sometimes lost during construction. Marcel Herssevoort illustrates what goes wrong with a few examples. “I don't do that to point an accusing finger at installers,” he emphasizes. “With my story I want to help the installer to make good choices.”

1. Hollow walls

The definition of fire-resistant hollow walls appears to be a major source of confusion. Herssevoort: “A double plaster wall is considered fire-resistant for 60 minutes. But, then the double plaster wall must be present on both sides of the metal stud. So there are four plasterboards in a wall system that can withstand fire for 60 minutes. As soon as you drill through one of the plasterboards, the wall system will no longer stop a fire for 60 minutes.”

Fire-resistant walls contain fire-resistant doors, which by definition have gaps. The Building Decree takes this into account, because it specifies a maximum permissible surface area for cracks. “It is then difficult to understand that you are not allowed to make one small hole in such a wall,” says Herssevoort. “Because what difference does that hole make on the surface of the cracks. Yet such a hole is disastrous for the fire resistance of the wall. Suppose you buy a boat, how many holes do you accept in the keel? None, because by definition water will flow in due to the water pressure. The same applies in the event of a fire. The pressure in the hot, burning room increases. Smoke and hot air look for a way out and find it in that little hole.”

So you can't just make a grommet for one cable, let alone a hole for a standard cavity wall box. You will then have to restore the fire resistance. Yet there is confusion about this. People have the idea that you can safely install a standard cavity wall box because there is still a double plasterboard on the other side, so the wall remains fire-resistant for 60 minutes. That is not the case, the fire resistance has been tested for the entire wall system, with four plasterboards.”

2. Certification

When it comes to electrical interventions in fire-resistant walls, the Building Decree does not prescribe anything. “The building code says that a wall must be fire resistant for 30, 60 or 90 minutes, depending on the time it takes to evacuate people safely. It is then up to the contractor to build such a wall and to the installers to guarantee that the wall remains fireproof, regardless of the number of penetrations and hollow wall boxes. We, and our better competitors, have all our products certified. This is done experimentally, in a wall system in a large oven at an accredited test institute such as Efectis or Peutz. A successful test results in an official report that guarantees the fire resistance.”

It is precisely when interpreting these test reports that a lot goes wrong, Herssevoort notices in practice. “There are parties that supply a whole range of products, of which they have one tested and then claim that their certificate guarantees that all their products are fire-resistant in all hollow walls and in all positions. This is not so. There is a big difference between a single, double or triple hollow wall box fitted with a wall socket or switch. The location in the wall also makes a difference. In the event of a fire, the temperature at the ceiling and therefore also the pressure is higher than at plinth height, the products must also be able to withstand this.”

A commonly used solution for fire resistance is 'sticking tapes' that you can stick in a standard box and which foam at a high temperature. Herssevoort: “We see that suppliers offer such products in which they refer to Attema's certificates and claim that they are therefore fire safe. We have already had several legal proceedings to stop this.”

The limited certification of some products may lead the installer to believe that he is doing well and safely. “If such solutions are 3 euros cheaper per hollow wall box and you have to install many hundreds of wall sockets in a care home, then I can imagine that you choose such a solution. That is not frugal, but very understandable. Remember, though, if things go wrong and research indicates that the fire could have spread through these wall outlets, then the turnips are done. You are then legally responsible for the bad installation and not the 'cowboys' who delivered your products with haggled certificates, that's how the law works in the Netherlands."

3. Fragmented knowledge.

How do you obtain sufficient knowledge about fire-resistant installation so that you can make well-considered choices for products and solutions? The installer will have to acquire the knowledge about fire-resistant installation himself. Installation technology courses pay little attention to it. “Most installers derive their knowledge from NEN1010 about electrical installations, but that includes 

nothing about fire-resistant installation. The requirements for this are in the Building Decree, but it is not so detailed that it prescribes what, for example, hollow wall boxes must comply. Installers are therefore dependent on the suppliers of fire-resistant solutions for their knowledge. The fire service used to give advice. However, the task of the fire service shifted from advising to checking. They disapprove of your work, after which you can figure out how to solve it.”

In the past Attema, together with experts and the fire service, organized workshops where installers could refresh their knowledge about fire resistance. “Unfortunately, the enthusiasm for this training diminished to such an extent that we stopped it,” says Herssevoort. In practice, he sometimes sees the consequences of the lack of knowledge. “Take buildings where people spend the night, such as hotels, hospitals and care homes. For example, compartments in the building must be fire-resistant for at least 90 minutes. After all, it takes time to sound the alarm, wake up and flee your room still disoriented. You don't just evacuate bedridden patients either. However, within a compartment, for example between hotel or hospital rooms, the walls in this subcompartment only need to be fire-resistant for 30 minutes. Many installers think that a standard product is fire-resistant by itself for 30 minutes, but that is not the case. We have already experienced a few times that the fire service rejected the work of an installer for that reason. Then you have to replace hundreds of hollow wall boxes at your own expense.”

Knowledge about hollow wall boxes and penetrations in the walls was undoubtedly present somewhere in the chain, from architect and contractor to the executing installer, but it did not end up in the right place. Herssevoort: “This is the core of the problem with knowledge in the chain, it is too fragmented, causing misunderstandings and confusion of tongues.”

4. Responsibility

In fact, the building owner is responsible for the fire safety of the building. However, during construction, that responsibility is continuously shifted to others. The owner passes it on to the contractor, who places the responsibility back on the subcontractors, such as the installer. “As an installer, you will therefore have to justify that you have delivered a fire-safe installation. According to the rules, you keep track of which solutions you chose and which materials you used in a project administration. This folder also contains the certificates and test reports that the producers provide. I notice that installers download our ready-made test reports from our easily accessible website to a very limited extent.”

The installer's responsibility does not end with strict adherence to the specifications. Even if there are errors in the specifications, the installer should not hide behind them. “We sometimes see that the specifications say nothing about fire-resistant penetrations in fire-resistant walls and that the installer does not apply them. The fire brigade will then also reject the building. Even if you receive approval, because the fire service simply cannot check the installation down to the smallest detail, you are still not exempt from your responsibility. If, after a fire, it turns out that your approved installation was not working properly, you are still responsible. After all, the stamp of the fire brigade is not above the law.”

Herssevoort increasingly sees installers shifting their responsibility for fire-resistant installations to companies that make all penetrations through walls fire-resistant. “If you opt for ready-made fire-resistant products, this is not necessary. Then you can keep the fire resistance in your own hands and you save the costs for an external company or you can get more turnover from your project.”

5. Future

Changes to fire safety in the building decree usually follow after incidents. If an investigation reveals an avoidable technical installation cause, the Building Decree will eventually intervene. One such incident was, for example, the fire at the airport in Düsseldorf, Germany. The fire killed 17 people, all of them from smoke and toxic gases. The fire made it clear that smoke is more dangerous and causes more victims than fire. “In the near future, the Building Decree will therefore set requirements for smoke resistance in buildings. Fire-resistant solutions often react to high temperatures, they start to foam and thus close the passage. However, smoke can also cool before it reaches a wall and then travel unhindered through a duct in the fire-resistant wall to another room. According to the new requirements, transits must be smoke resistant, both at 20 oC and at 200 oC. In addition, it is recommended or even prescribed that installation must be done with halogen-free materials. After all, in the event of a fire, toxic gases such as hydrochloric acid are released. This also happened in Duesseldorf. Because smoke resistance is a completely new item, about which there is still little knowledge, we are once again considering organizing workshops for installers and work planners," concludes Herssevoort.

Source File: Installatiejournaal