Restriction of a fire and minimization of fire and smoke spread is a key target in all building codes and regulations. The easiest way to solve this challenge and the most cost efficient solution for architects and designers is fire compartmentation. It is mandated in all national building regulations all over the world and provides precautions, limitations, clear rules on the size and location and type of construction of fire compartments. It is as well a concern for building owners and insurance companies, not only in respect to life safety, but also in respect to asset protection. But why is it so important, what are the benefits and the hidden risks of fire compartments?


The theory of fire compartmentation in codes and regulations

Every building must be constructed in such way, that in the event of a fire in the building, fire and smoke is limited from spreading. The spread of fire and smoke can be restricted by dividing a building into separate compartments with fire-resistive walls and floors—increasing the availability of escape routes for occupants. In that respect, compartmentation protects escape routes such as corridors or stairs.
Technically speaking, compartments stop the fire spreading, limit the fuel supply and cut off the supply of oxygen therefore attack the three main sources of a fire: heat, fuel and oxygen.
Therefore the concept of fire compartments has found its way into all building codes and regulations as one of the most important principles of passive fire protection. Already one of the first general fire regulations in Bavaria, Germany from 1791 said, that certain areas in a building must be separated so that fire cannot spread over from one area to the other.

In summary: a fire compartment is an area within a building which is completely surrounded with fire-resistant construction. Fire compartments are required by law in some types of buildings, and strongly recommended in others as a basic safety measure. Some insurance companies may also demand that fire compartments be installed before they will write policies for certain types of businesses, in the interests of reducing their liability.1)


The principle of fire walls and floors in a building


The goals are not absolute but related to time. They are to guarantee:
- building will not collapse or become unstable.
- protect fire fighters and escape routes, reduces the chance of fires growing and creating a danger to occupants and people in the vicinity of the building: more than 40% of deaths were people who were not in the room of origin
- safe property: many billion $ insured losses but also many times more uninsured losses per year
- stop the spread of smoke: smoke travels between 50 and 300ft per minute, 2/3 of fire related deaths are through smoke inhalation

In many regulations, a building should be divided by compartment walls and floors. These walls and floors must have a minimum fire resistance duration. But buildings are different in type, purpose, size and life risk to occupants. In most cases, for example, a single story family house poses less life risk than a multi-storey large scale hospital or shopping center.


Level of fire protection requirements in the regulations

Therefore additional guidance is given in different national regulations:
- type of building, building use (e.g. hospital, shopping center, residential care building, factory, entertainment)
- size of building (e.g. number of storeys, height of the building)
- size of compartment (e.g. maximum distance from one to another compartment wall, maximum area of a compartment)
- location of compartments (e.g. near escape routes and hallways, shafts)
- places of special fire risk (e.g. storage rooms with special hazardous liquids)
- fire resistance duration (e.g. minimum fire resistance of 90minutes)


What are the hidden hazards of fire compartments?

Compartment walls and floors are intended to prevent the passage of fire and smoke from one compartment to another. But these compartment walls and floors also leave openings for required cable, duct or pipe works, so-called service penetrations. These required service penetrations should be kept to a minimum but are just required and necessary in a building. Lighting, electrical supply, heating and water distribution, ventilation and air conditioning, telecommunication lines and many other services are also installed in buildings and have to pass from compartment to compartment in defined or sometimes not-at-all defined ad-hoc created openings.
On top, many trades and contractors are involved in the installation of the different services, like drywallers, insulators, electricians and HVAC contractors. This makes the actual firestopping a quite complex job which can only be solved with clear pre-planning or specification. Many times, the correct and compliant closing of the service penetrations according to the required fire rating is left to the last party on the jobsite.
As firestopping materials do have approvals and are tested according to clearly defined test standards, the correct installation is sometimes not an easy task. Therefore, the brutal fact is that many firestop penetrations through fire rated compartments remain incorrectly firestopped, firestopped with wrong material and not according to the relevant approval or even remain open. This then represents one of the major risks in a building as fire and smoke is free to travel all over the building and the compartment will not fulfill its intended and legally required purpose anymore.



Typical high risk areas in compartments: unsealed pipe, cable penetrations and joints in between building elements

The correct installation of firestop is important. In case of a fire, plastic pipes or cables melt and create toxic gases. Metal pipes and high voltage cables transfer heat. Firestop materials expand and automatically close off the openings and assure the correct fire integrity of the wall or floor. Firestop also provides resistance to the transfer of excessive heat and the ability to provide insulation from high temperatures.

Smoke tightness should never be forgotten as smoke (cold smoke) is one of the key killers in an event of fire (toxicity). Smoke travels fast and even long before the fire becomes a danger. On top smoke will also destroy assets and equipment throughout the building compartments. Therefore a tight seal must be ensured.
In the picture below, a real case fire with the impact of cold smoke, far away from the origin of the actual fire was documented: within not even 2 minutes the hallways and all areas in this hospital were basically full of toxic smoke. Reason; unsealed service penetrations.


Fire and smoke propagation in a hospital (Turku, Finnland, 02.Sep.2011)2)


Keeping fire rated assemblies firestopped over the lifetime of the building

Many times, due to cost and budget restrictions, firestop is not considered or just considered as a minor issue. This is not necessary if building owners, architects, designers and general contractors take the correct firestop specifications and measures in an early phase of the construction project. It is their legal responsibility.

Another key question is how to keep the firestopped walls and floors intact over the lifetime of the building. So it is not only relevant for new construction but especially when it comes to the occupancy phase of a building when fire probability is at it’s highest risk. Analysis of potential reasons of a fire show that fires can start any time anywhere. 35% of fires are due to electricity problems (short circuit), almost 10% are caused by overheating of installations, 17% are caused by human error and in 22% of fires the ultimate cause remains unsolved 3). 

During the lifetime of a building, many extensions, new rebuilding and retrofitting measures are taken. New cabling due to new communication or emergency systems, upgrades of electrical equipment, new seperations of office space with new drywall partitions and new content with different fire loads, renovation of interiors, extensions of ventilation or heating equipment, maintenance of piping and duct work will also have dramatic implications on the status of the firestopping penetration seals. In this process, different trades and maintenance staff will have to break and damage existing fire rated penetration seals.

- Who then is maintaining the correct fire rating of the penetration seals?
- Who will close open or damaged openings in fire rated walls?
- Are the same approved and tested systems used to close the sealings?
- And are all deficient and damaged seals correctly reported and documented to the owner of the building?

There is a high probability that non-correctly closed and damaged firestopping seals in fire rated assemblies pose huge hazards in existing buildings.

     
In many existing buildings incorrect installations are very likely to be seen

     
Broken and damaged firestop seals represent high fire and smoke risk. Proper maintenance of fire rated walls and floors in existing buildings is key


What are some of the long term solutions for building owners and responsible facility maintenance companies and how to ensure compartmentation remains intact during a renovation or restructuring phase:

- Education of your staff and contractors about compartmentation and firestop penetrations
- Set clear expectations and communicate these to responsible contractors including firestopping
- Proper and fast maintenance of damaged or deficient penetrations by trained and qualified installers, also considering approval compliant installation
- Usage of correct firestopping material (also in line with existing firestop material)
- Do inspection rounds annually or whenever adequate
- Generate a clear documentation of firestop penetrations and deficiencies (e.g. by using a specific software for firestop documentation management including pictures and labelling), maintain and file documentation reports


Regular inspection and maintenance of firestopping in existing buildings is equally important to reduce the risk for people and protect assets in an event of a fire

- Label smoke and fire walls and floors
- Consider correct passive fire protection in your risk assessment
- Write a comprehensive specification of firestop material to be used based on ease of installation, approved field of application, retrofit possibilities, easy maintenance and inspection
- Choose an experienced firestop manufacturer who also offers technical onsite support and consultation
- Reduce your risk by choosing easy to maintain firestop materials like pre-engineered devices or easy to inspect preformed products (Firestop Blocks, Firestop Sleeves) which offer clear cost advantages when it comes to long term maintenance and proper installation.



  
Pre-engineered firestop devices like a Firestop Sleeve for total cable management: easy to retrofit during the building lifecycle


The new Firestop Cable Collar for surface-mounted installations: easy to install and inspect


Hilti is the global market leader in firestopping. Our dedication to stringent testing and code developments help make buildings safer today, saving lives and protecting asset, with proven reliability and outstanding service.
Hilti, with own worldclass research and development is committed to supply easy-to-use firestop solutions, providing cutting-edge and fully integrated and tested systems. At the end of the day, together with a unique professional technical support in many countries, this helps specifiers and installers to correctly select the right system for the right application and also to correctly specifiy compliant and tested solutions.


Need a support or have a question related to this article?

• If you have any question related to the article or related to passive fire protection, you can post your question on ask Hilti platform,
• You can access our series about Saving Lives In Modern Buildings to get a better understanding of firestop products.
• Leave a comment down below if you have ever done firestopping installation or design, share your experiences with everyone.

References:

1) wiseGEEK, 2003 - 2016 Conjecture Corporation
2) Safety Investigation Authority, Finland, www.turvallisuustutkinta.fi
3) Feuer Trutz Brandschutzatlas 3/2012

Other sources and pictures: internal Hilti Aktiengesellschaft, Schaan, Liechtenstein