Fire compartmentation means dividing a building into zones with fire-resisting walls and floors so that fire and smoke are held in the zone where they start for a certain time. The Turkish Regulation on Fire Protection of Buildings (BYKHY) defines the concept in Article 4, gives its rules in Article 24 and leaves the numbers to three annexes: hazard classes in Annex 1, fire resistance periods in Annex 3/B and Annex 3/C, and maximum compartment areas in Annex 4. This article starts from the definition and explains the tables one by one by hazard class.
Definition: Article 4(tt)
Under BYKHY Article 4(1)(tt), a fire compartment is:
"A zone within a building divided into smoke- and heat-tight areas by building elements resistant to fire for at least 60 minutes on every side, including the ceiling and floor slabs." (unofficial translation)
Four conditions follow from the definition:
- It is enclosed on every side. Not only the walls but also the ceiling and floor slabs are part of the compartment. A floor with a non-fire-resisting slab is not a compartment, however robust its walls are.
- It resists for at least 60 minutes. 60 minutes is the lower limit; depending on the building type and height, the required period rises to 90 or 120 minutes in Annex 3/C.
- It is smoke- and heat-tight. Not only flame but also the passage of smoke and heat is prevented. Doors, service penetrations and joints are therefore the weakest points of a compartment.
- It is continuous. Article 24(7) requires the fire resistance of the elements enclosing a compartment to be continuous at the junctions as well, and no non-fire-resisting openings between compartments.
There are two further definitions related to compartments. Progressive horizontal evacuation (4(1)(s)) is occupants moving away from the fire and taking refuge in the adjacent fire-tight compartment on the same floor; it is the basis of the escape strategy in places such as hospitals. A fire curtain (4(1)(uu)) is a specially equipped barrier that prevents the horizontal or vertical spread of heat.
Compartment wall, fire wall and floor
These three concepts are often confused:
| Element | What does it separate? | Minimum resistance | Basis |
|---|---|---|---|
| Fire wall | Adjoining (terraced) buildings from each other | 90 minutes | Article 25(1) |
| Compartment wall (separating different uses) | Different use functions within the building | REI 60 or Annex 3/C (whichever is greater) | Annex 3/B row 6 |
| Compartment wall (other) | Zones of the same use within the building | Annex 3/C | Annex 3/B row 7 |
| All floors, including compartment floors | Storeys | Annex 3/C | Annex 3/B row 3-c |
| Floor between basement and ground floor | The basement from the upper floors | REI 90 or Annex 3/C (whichever is greater) | Annex 3/B row 3-d |
Article 26(1) requires all floors to have the quality of a fire wall; in other words, in a multi-storey building every floor slab is in fact a compartment boundary. If openings such as doors or fixed lights in a fire wall cannot be avoided, they must resist fire for at least half the resistance of the wall, and be self-closing and smoke-tight (Article 25(2)).
Which spaces must be compartments?
Article 24 and the use-specific articles require certain spaces directly as compartments:
- Article 24(2): Walls shared by two or more buildings, and the walls and floors of boiler rooms, car parks, main electrical distribution rooms, in-building transformer stations, medium-voltage substations, generator rooms and similar enclosed spaces with a fire hazard, have the properties of a compartment wall.
- Article 24(3): Common walls belonging to two or more buildings are built as fire-resisting walls; every wall separating semi-detached houses is a fire wall and the houses are treated as separate buildings.
- Article 24(4): In non-residential buildings with a building height of more than 21.50 m and in residential buildings of more than 30.50 m, on the floors above these heights at most three floors are arranged as one fire compartment.
- Article 24(5): Atria are permitted only in buildings made up of low and medium hazard uses; the atrium area must not be less than 90 m² at any point.
- Article 49(1)(b): Each sleeping floor larger than 300 m² in hospitals and care homes is divided into two or more compartments, each at least half the size, or protected horizontal evacuation areas are formed.
- Article 50(1)(ç): In hotels, other rooms opening onto the bedroom corridor must have the same level of compartmentation as the bedrooms.
Hazard classes and compartments (Article 19, Annex 1)
Article 19(2) requires the hazard classification to be taken into account when compartments are formed, and defines three classes:
| Class | Article 19(2) definition | Annex |
|---|---|---|
| Low hazard | Places containing materials with a low fire load and combustibility, resistant to fire for at least 30 minutes and with no single compartment area larger than 126 m² | Annex 1/A |
| Ordinary hazard | Places containing combustible materials with a moderate fire load and combustibility | Annex 1/B (OH-1, OH-2, OH-3, OH-4) |
| High hazard | Places containing materials with a high fire load and combustibility that would cause a fire to spread and grow quickly | Annex 1/C (HH-1 … HH-4) |
The compartment appears directly in the low hazard definition: for a space to count as low hazard, it must have no part larger than 126 m² and must be resistant to fire for at least 30 minutes. Annex 1/A gives as examples of this class certain areas of schools and other educational institutions and of offices that do not fall within Annex 1/B and Annex 1/C, and prisons.
Annex 1/B: Ordinary hazard uses (examples)
| Class | Examples in Annex 1/B |
|---|---|
| Ordinary Hazard-1 | Cement works; sheet metal production; slaughterhouses, dairies; hospitals, hotels, dwellings, restaurants, libraries (excluding book stores), schools, offices; computer data processing offices (excluding data storage rooms) |
| Ordinary Hazard-2 | Photographic laboratories and film factories; car factories and repair workshops; bakeries, biscuit, chocolate and confectionery works, breweries; physics laboratories, laundries, car parks, museums; leather goods factories |
| Ordinary Hazard-3 | Glass factories; dyeing processes, soap factories; electronics, refrigerator and washing machine factories; animal feed, fruit drying, sugar works, grain mills; radio and television broadcasting stations, railway stations, plant rooms; bookbinders, cardboard and paper factories, printing works; cable, plastic moulding and plastic goods (excluding foam plastics), rubber goods, synthetic fibre (excluding acrylic) and vulcanising factories; department stores, shopping centres; carpet, fabric and clothing, footwear, knitwear, home textile, bed and mattress factories (excluding foam plastics), weaving workshops; woodworking and furniture factories, furniture shops |
| Ordinary Hazard-4 | Candle, beeswax and match factories, dye works; alcohol distilling; cinemas, theatres, concert halls, tobacco factories; exhibition halls; waste paper plants; rope factories; cotton spinning mills, flax and hemp preparation; wood shavings, chipboard and plywood factories |
The note to Annex 1/B is important: if Ordinary Hazard-1 and Ordinary Hazard-2 uses contain dyeing processes or similar areas with a high fire load, the use is assessed as Ordinary Hazard-3. If a car repair workshop has a paint booth, the area becomes OH-3 and falls to a tighter limit in Annex 4.
Annex 1/C: High hazard uses (examples)
| Class | Examples |
|---|---|
| High Hazard-1 | Upholstery fabric and oilcloth factories; manufacture of paints, colourants and varnishes; manufacture of synthetic rubber, resin, lamp black and turpentine; sawdust factories, wood wool manufacture |
| High Hazard-2 | Flare factories; plastic foam and sponge works; tar distilling; bus depots, loaded lorries and wagons, depots for buses and unloaded lorries |
| High Hazard-3 | Cellulose nitrate factories |
| High Hazard-4 | Fireworks factories |
If different parts of a building have different hazard classes, the water and pump capacity is determined by the highest class (Article 19(1)). If different uses cannot be separated by a fire-separating element suited to the higher hazard class, the rules of the stricter class apply to the whole building (Article 18). Compartmentation is therefore the tool that makes it possible, in a mixed-use building, to separate two classes from each other and apply each its own rules.
Annex 4: Maximum compartment areas
Article 24(6) leaves the maximum compartment area required in buildings to Annex 4. In the table, only the industrial and storage rows are split in two by hazard class:
| Building use class | Hazard class | Maximum compartment area | Note |
|---|---|---|---|
| Dwellings | — | Unlimited | |
| Accommodation | — | 4,000 m² | (1) |
| Institutional: healthcare | — | 1,500 m² | (1) |
| Institutional: education | — | 6,000 m² | (2) |
| Offices | — | 8,000 m² | (1) |
| Commercial (4) | — | 2,000 m² | (2) |
| Assembly: food and drink, entertainment, museums and exhibitions | — | 4,000 m² | (2) |
| Assembly: other | — | 6,000 m² | (2) |
| Industrial buildings | Ordinary Hazard-3 and above | 6,000 m² | (2) |
| Industrial buildings | Ordinary Hazard-1 and 2 | 15,000 m² | (3) |
| Storage | Ordinary Hazard-3 and above | 1,000 m² | (2) |
| Storage | Ordinary Hazard-1 and 2 | 5,000 m² | (3) |
| Enclosed car parks | — | No limit |
Notes:
- (1) If suitable fire control systems (automatic detection, sprinkler system, smoke extraction system and the like) are installed, the compartment area may be doubled.
- (2) If suitable fire control systems are installed, the compartment area is unlimited.
- (3) If the building is single-storey there is no limit; if suitable fire control systems are installed, the compartment area is unlimited.
- (4) Fruit and vegetable markets, fish markets, meat exchanges, places holding metal spare parts and similar places are outside the commercial row.
The notes list the systems as examples; one of them (for example automatic detection alone) satisfies the condition of the note. The tightest row of the table is OH-3 and above storage: 1,000 m²; this limit is not lifted even in a single-storey warehouse, because the single-storey concession exists only in note (3) of the OH-1/2 rows. For how the notes are applied and further detail, see Fire Compartment Areas: BYKHY Annex 4 Table and Article 24 and unlimited compartment area with sprinklers.
Annex 3/C: Fire resistance periods of compartment elements
Under Article 24(1), the resistance of compartment walls and floors is referred to Annex 3/B, and Annex 3/B in most rows refers on to Annex 3/C. Annex 3/C gives the periods by use class, presence of a sprinkler system, basement depth and building height (minutes):
| Use | Sprinklers | Basement > 10 m | Basement < 10 m | Building < 5 m | Building < 21.50 m | Building < 30.50 m | Building > 30.50 m |
|---|---|---|---|---|---|---|---|
| Single-family and two-family houses | — | — | 30 (2) | 30 | 60 | — | — |
| Apartment buildings | — | 90 | 60 | 30 (2) | 60 | 90 | 120 |
| Accommodation | no | 90 | 60 | 60 | 60 | 90 | not permitted |
| Accommodation | yes | 60 | 60 | 30 (2) | 60 | 60 | 120 (3) |
| Institutional | no | 90 | 60 | 60 | 60 | 90 | not permitted |
| Institutional | yes | 90 | 60 | 30 (2) | 60 | 90 | 120 (3) |
| Offices | no | 90 | 60 | 30 (2) | 60 | 90 | not permitted |
| Offices | yes | 60 | 60 | 30 (2) | 30 (2) | 60 | 120 (3) |
| Commercial | no | 90 | 60 | 60 | 60 | 90 | not permitted |
| Commercial | yes | 60 | 60 | 30 (2) | 30 (2) | 60 | 120 (3) |
| Industrial | no | 120 | 90 | 60 | 90 | 120 | not permitted |
| Industrial | yes | 90 | 60 | 30 (2) | 60 | 90 | 120 (3) |
| Assembly | no | 90 | 60 | 60 | 60 | 90 | not permitted |
| Assembly | yes | 60 | 60 | 30 (2) | 60 | 60 | 120 (3) |
| Storage | no | 120 | 90 | 60 | 90 | 120 | not permitted |
| Storage | yes | 90 | 60 | 30 (2) | 60 | 90 | 120 (3) |
| Open car parks | — | — | — | 15 (2)(4) | 15 (2)(4) | 15 (2)(4) | 60 |
| Other car parks | — | 90 | 60 | 30 (2) | 60 | 90 | 120 (3) |
Basement depth is the distance between the lowest basement floor slab and the ground floor slab. Annex 3/C notes:
- (1) The floor above a basement (or, where there is more than one basement, the floor above the uppermost basement) must meet the requirement for the entrance and upper floors if that period is greater.
- (2) Increased to at least 60 minutes for fire compartment walls separating buildings.
- (3) May be reduced to 90 minutes for elements that do not form part of the structural system.
- (4) Increased to 30 minutes for elements forming the emergency escape.
Although the table has 30-minute cells, the definition in Article 4(tt) requires every side of a compartment to be resistant for at least 60 minutes. Elements used as compartment boundaries do not go below 60 minutes. In addition, the words not permitted in the cells for a building height above 30.50 m in accommodation, institutional, office, commercial, industrial, assembly and storage buildings without a sprinkler system show that these buildings cannot be built without sprinklers; Article 96(2)(a) also makes sprinklers mandatory in non-residential buildings with a structure height above 30.50 m.
Other compartment-related rows of Annex 3/B
| Element | Resistance |
|---|---|
| Protected shafts (excluding fire escape stair enclosures and emergency lift shafts) | REI 120 |
| Wall separating a protected fire escape stair enclosure, emergency lift shaft and fire lobby from the rest of the building | REI 120 |
| Wall separating these from each other | REI 60 |
| Fire stop | EI 30 |
| Suspended ceiling | EI 30 (from below) |
In high-rise buildings, the walls of vertical service shafts and flues such as refuse, communication, document and technical equipment shafts must be resistant to fire for at least 120 minutes and their access doors for at least 90 minutes, and be smoke-tight (Article 25(3)).
Service penetrations: the weak point of a compartment
The most common mistake that breaks a compartment is not the wall but the services passing through it:
- Ventilation ducts: Ducts must not penetrate compartment walls. If a duct has to pass through a 120-minute compartment wall or floor, a fire damper or a measure that prevents the passage of fire, such as a shunt flue or a special collar, is fitted at the crossing; a fire damper is mandatory at the entry to and exit from a protected shaft (Article 87(8)).
- Shared air handling unit: If the same air handling unit serves more than one compartment, fire dampers are fitted in the supply and extract ducts at the crossings between compartments (Article 87(6)). Fire dampers are not used in pressurisation ducts (Article 87(9)).
- Flues and ducts: Service flues and ducts that play a role in fire spread are aligned with the compartment and insulated so as not to reduce the compartment's fire resistance; except for special details, they are not allowed to cross compartments (Article 87(11)).
- Pipes and cables: Where water, electrical, heating and ventilation services pass through a fire wall, the gap around them is sealed against the passage of fire and smoke, leaving no opening, for at least the fire resistance period of the wall (Article 25(2)). If soil pipes of normally flammable material are used, fire stops with the fire resistance period of the compartment wall are used where they pass through floors (Article 29(4)).
Example: same area, three different outcomes
Consider a 12,000 m² single-storey building:
- Furniture factory (Annex 1/B, OH-3): Annex 4 limit 6,000 m² (note 2). The building is divided into at least two compartments, or the limit is removed by installing a suitable fire control system. There is no single-storey concession for OH-3.
- Sheet metal production (Annex 1/B, OH-1): Annex 4 limit 15,000 m² (note 3); moreover, as the building is single-storey there is no limit. The 12,000 m² can be a single compartment.
- OH-3 materials warehouse: Annex 4 limit 1,000 m² (note 2). Without a system, 12 compartments are needed; with a suitable fire control system the limit is lifted. Even though the warehouse is single-storey, the OH-3 row has no single-storey concession.
If the same building is an unsprinklered industrial building with a building height between 5 m and 21.50 m, the compartment elements must be resistant for 90 minutes under Annex 3/C; with a sprinkler system this value falls to 60 minutes.
Common mistakes
- Forgetting the floor: The definition says "including the ceiling and floor slabs"; an area enclosed only by walls, with a non-fire-resisting floor, is not a compartment.
- Treating the door separately from the wall: If the door in a compartment wall is not self-closing and smoke-tight, the compartment does not work.
- Leaving service penetrations undetailed: Every penetration without a damper, fire stop or sealing detail breaks the continuity requirement of Article 24(7).
- Reading the hazard class from the use name: The Annex 4 row of a "warehouse" is 1,000 m² or 5,000 m² depending on the hazard class of the goods inside. An OH-1/2 facility with a paint section counts as OH-3.
- Applying a 30-minute cell to a compartment boundary: The 30-minute values in Annex 3/C are not enough for a compartment boundary; the definition requires at least 60 minutes.
FAQ
What is a fire compartment?
Under BYKHY Article 4(tt), a fire compartment is a zone within a building that is divided into smoke- and heat-tight areas by building elements resistant to fire for at least 60 minutes on every side, including the ceiling and floor slabs. The aim is to hold the fire and smoke in the zone where they start for a certain time.
What is the minimum fire resistance of a compartment wall?
By definition, at least 60 minutes. The actual period is read from Annex 3/B and Annex 3/C: compartment walls separating different uses within the building take REI 60 or the Annex 3/C value, whichever is greater; other compartment walls and floors rise directly to 60, 90 or 120 minutes under Annex 3/C.
What does the compartment area in Annex 4 depend on?
It depends on the building use class and, for industrial and storage buildings, also on the Annex 1 hazard class. For example, in storage buildings the maximum is 1,000 m² for Ordinary Hazard-3 and above, and 5,000 m² for Ordinary Hazard-1 and 2. With suitable fire control systems the area is doubled or becomes unlimited; in OH-1/2 industrial and storage buildings there is no limit if the building is single-storey.
Are a fire wall and a compartment wall the same thing?
No. A fire wall (Article 25) separates adjoining buildings from each other and is designed to resist fire for at least 90 minutes. A compartment wall separates zones within a building; its period comes from Annex 3/B and Annex 3/C and is at least 60 minutes. Article 26(1), in turn, requires all floors to have the quality of a fire wall.
Can a ventilation duct pass through a compartment wall?
Article 87(8) requires ducts not to penetrate compartment walls; if a duct has to pass through a 120-minute compartment wall or floor, a fire damper or a measure that prevents the passage of fire, such as a shunt flue or a special collar, is fitted at the crossing. If the same air handling unit serves more than one compartment, fire dampers are mandatory in the supply and extract ducts at the compartment crossings (Article 87(6)).
References
- Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments (current consolidated text); Articles 4(1)(s), 4(1)(tt), 4(1)(uu), 18, 19, 24, 25, 26, 29(4), 49, 50, 87; Annex 1/A, Annex 1/B, Annex 1/C, Annex 3/B, Annex 3/C, Annex 4. mevzuat.gov.tr
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Download MEP Calc on the App StoreSources are listed in the References section at the end of the article. Quotations from the regulation are unofficial English translations of the Turkish text. This article is for general information; for article numbers, thresholds and exemptions, the current regulation and standard texts published in the Official Gazette govern, and design must be carried out by an authorised engineer.