30/04/2026
Passive fire protection systems, mandatory by law and present in all buildings, are integrated fire protection solutions that resist and limit the spread of fire and smoke.
Concept, context and problems
When we think about fire protection, we usually imagine devices like detectors, push buttons, extinguishers, hydrants, and sprinklers. All of them are indeed part of the active protection of a building: installed systems that activate (manually or automatically) to detect, alert, and, in some cases, control or extinguish a fire.
Less visible, and perhaps for that reason, less talked about, are the other solutions integrated into buildings that resist and limit the spread of fire and smoke. We’re talking about passive fire protection.
Passive protection systems, like active protection, are present in every building and it’s obligatory to have them installed prior to obtaining an occupational license to commence activity.
The regulations are clear when prescribing the passive needs in buildings; however, there is no national framework that establishes routines or inspection frequency for them as a whole.
Although the regulations clearly indicate that the building must ensure and maintain the basic fire safety requirements for which they were designed, there is no framework regulating the maintenance checks to be carried out to prevent deterioration, keep the system in good condition and ensure reliability of these systems. The consequences are something we’ve all seen at some point. Who among us hasn’t seen a fire-resistant door anchored in an open position with a wedge?
Unfortunately, examples such as this are very common and are the result of a lack of attention or knowledge and maintenance of these systems, simply due to ignorance or a lack of control by facilities management.
With the aim of boosting awareness of passive protection, this article will focus on those measures offering the greatest impact on controlling the spread of the fire: sectorization (known as compartmentalizing in the world of fire protection) and the limitation of internal and external propagation. The purpose is to provide a basic evaluation base that can be used to determine the suitability and maintenance of these measures in a given building.
How can I ensure my building is properly passively protected?
The first step is to identify the passive protection measures of our building and treat them as such. There follows a list of the most important and significant measures, as well as their main functions and the elements they include.
Sectorization
A fire sector is defined as an interior area of a building in which a fire can be confined for a determined period of time, so that it cannot spread to (or from) other sectors, thanks to fire-resistant construction elements.
If the maximum surface area of a sector is exceeded, more fire load than expected is concentrated in that area and the building may not respond as it was designed to. For example, an expanded warehouse, be it in terms of floor area or volume of material stored, may require reinforced levels of protection: improving the fire resistance of the structure, building new fire-resistant walls that define an additional sector, and/or even implementing new active protection systems.
Internal propagation
Internal propagation is understood to refer to the degree of fire resistance protection of the elements delimiting the fire sector at all its points, including the elements that cross it. As such, any passageway in the facility, whether for use by people or vehicles, that connects two different sectors must have the required degree of protection for the space it traverses.
It’s usually at this point where most anomalies related to the protection conditions are detected. To guarantee an adequate degree of protection, we must consider different elements:
a. Fire doors
A fire door is possibly the most common and recognizable passive protection element in a building since they’re used to facilitate the passage of people or vehicles between different sectors. However, they aren’t guaranteed to always function correctly.
Every fire door must close automatically without human intervention, which means they must be fitted with self-locking devices and a door selector if it’s a double-wing door. If these doors have to be open, anchoring devices such as retainers or magnets must be installed, which are activated via the fire protection system (mainly through detection and alarms or sprinklers) of the contiguous fire sectors.
In any case, blocking doors with items that prevent them from closing autonomously (using wedges, chains, or heavy items) must be avoided.
It must also be acknowledged that modifying fire doors and consequently altering the conditions in which it left the manufacturer (be it intentionally or accidentally, by causing damage to the frame, repeatedly painting it or not replacing missing the intumescent seals) can affect the degree of fire resistance of the door.
b. Facilities conduits
The passage of installations through delimiting elements must maintain the relevant degree of protection at all points, including hidden spaces, for all types of passage, whether hollow or not. Here we’re talking about cable trays, cable ducts, galleries, piping, conduits, conveyor belts, etc.
Steps must be taken to ensure that all spaces and installation passages maintain the same fire resistance level as the delimiting element they pass through, meaning the cable trays must be sealed using intumescent systems: plastic pipes must have collars, while on rigid pipes, the all gaps need to be properly filled. In openings that require throughflow, such as ventilation systems, automatic fire-resistant dampers can be used, or the installation can be protected all along its entire route when it passes through another sector.
External propagation
It’s also very important to keep in mind that fires don’t only spread inside a building; they can also spread outside through windows, nearby doors, or skylights. The exterior propagation of a fire between two sectors can occur horizontally, vertically, and even through the roof.
There are a number of different ways to limit a fire spreading externally, including:
a. Horizontal limitation
To limit the exterior spread through the facade between contiguous sectors, the regulations indicate maintaining a minimum distance between openings belonging to different sectors.
When this distance cannot be maintained, the openings must have a fire-resistant degree of protection or be complemented with constructive projections that are continuous with the separating element.
Likewise, the presence of combustible storage near the facade should be avoided, as it can facilitate a fire spreading.
b. Vertical limitation
To limit the vertical spread of the fire on the facade between sectors located at different heights, the vertical distance between exterior openings of different sectors must be considered.
The regulations indicate installing a protective strip with a certain degree of fire-resistant protection. When it’s not possible to respect the height, an outgoing escape can be used in continuity with the element that separates the sectors.
This criterion is especially relevant on facades with combustible materials, such as those featuring an ETICS (External Thermal Insulation Composite Systems) system, where the strip must extend at each slab junction. In facades with ventilated cavities, it’s necessary to incorporate fire-resistant barriers or intumescent elements continuous with the slabs to limit vertical propagation.
c. Rood limitations
Fire spread can also be limited by using the roof structure of a facility. Doing this necessitates respecting a minimum distance between roof openings or in the joints between roofs and facades of different fire sectors.
When roofs don’t incorporate fire-resistant protective measures, it’s possible to use a protective strip at the junction or extend the delimiting element of the sector above the roofline. At roof-facade joints, if it’s not possible to maintain the minimum distance, the openings must have fire-resistant protection.
Conclusions
After years of conducting risk inspections from an insurance perspective with regard to damage protection and loss of earnings, I have found that passive protection measures are not always considered when new operational needs arise or significant reforms are undertaken: interior redistributions, changes in use, storage expansions or even actions aimed at energy efficiency.
In fact, most anomalies are not detected in buildings under construction, but in those buildings already in operation. This generates a frustrating feeling: passive protection is well designed and properly implemented at the start of the activity, but over time — and especially with daily activity and successive modifications — its performance degrades without anyone noticing the consequences it has. Doors that stop closing, boundary walls perforated by the passage of new installations, seals that disappear after a renovation… small changes that, when combined, can nullify the function of stopping the spread of a fire.
The paradox is clear: passive protection is less visible, but it’s critical in limiting the spread of fire and smoke. It plays a fundamental role in minimizing damage and giving people time to evacuate a burning structure, which in turn facilitates intervention on the part of firefighting professionals. Therefore, beyond initial compliance, the real challenge is to ensure its continuity over time, incorporating its verification into enterprise maintenance culture and particularly where the control of changes is concerned.
In passive protection, the risk doesn’t always originate in the design – it often arises from the silent wear and tear of day-to-day life.
Javier Rubio Vela
Risk engineer
