A fire compartment is a zone within a building that is divided off, on every side including the ceiling and floor slabs, into smoke- and heat-tight areas by building elements with at least 60 minutes of fire resistance (Turkish Regulation on Fire Protection of Buildings (BYKHY), Article 4(tt)). The decisive phrase in the definition is "on every side": the separation is not a wall but an envelope, and it is only as good as its weakest penetration.
How compartment areas are determined by use class is given as a table in the article on fire compartment areas. This article is about details, not areas: resistance symbols, the rules on openings and penetrations, and the continuity provisions on the floor, facade and roof sides.
Two separate definitions: compartment and fire wall
The Regulation defines the two terms separately:
- Fire compartment: A zone within a building that is divided off, on every side including the ceiling and floor slabs, into smoke- and heat-tight areas by building elements with at least 60 minutes of fire resistance (BYKHY Article 4(tt)).
- Fire wall: A vertical element that stops the progress and spread of a fire for a specified period where volumes with different fire loads must be separated from each other, between two buildings or within the same building (BYKHY Article 4(rr)).
In other words, the fire wall is the vertical part of the compartment envelope; the rest of the envelope consists of floors, ceilings, doors and penetrations.
The text lists which spaces have walls that count as compartment walls: shared walls, and the walls and floors of boiler rooms, car parks, main electrical distribution rooms, transformer and medium-voltage substations, generator rooms and similar enclosed spaces with a fire hazard, have the properties of a compartment wall (BYKHY Article 24(2)). Every wall separating semi-detached houses is built as a fire wall and the houses count as separate buildings (BYKHY Article 24(3)).
The boiler room is the best-known member of this list: the boiler room is located in a central place as a single unit, separated from the other parts of the building by partitions with at least 120 minutes of fire resistance; a building expansion joint cannot pass through the boiler room (BYKHY Article 54(2)). The ways this is violated on site are covered in the article on the boiler room 120 minutes rule.
Resistance symbols and periods
The fire resistance symbols are given in Annex 3/A, the resistance periods of building elements in Annex 3/B, and the periods by building use class in Annex 3/C (BYKHY Article 29(7)). The Annex 3/A symbols are in the Regulation text itself: R load-bearing capacity, E integrity, I insulation, W radiation, M mechanical resistance, C self-closing, S smoke leakage.
The Annex 3/B rows used most in project practice are:
| Building element (Annex 3/B) | Resistance |
|---|---|
| Fire compartment walls (separating different use functions) | REI 60 or Annex 3/C, whichever is greater |
| Protected shafts (excluding protected 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 |
| Floor between basement and ground floor | REI 90 or Annex 3/C, whichever is greater |
| Fire stop | EI 30 |
| Suspended ceiling | EI 30 |
There is a separate value for adjoining buildings: fire walls separating adjoining (terraced) structures from each other are designed for at least 90 minutes of fire resistance (BYKHY Article 25(1)). In high-rise buildings, the walls of vertical service shafts and ducts such as refuse, communication, document and technical equipment shafts must have at least 120 minutes of fire resistance, and their hatches at least 90 minutes, and be smoke-tight (BYKHY Article 25(3)).
No holes or openings
Article 25(2) is the strictest provision on this subject and contains four rules: there can be no holes or openings in fire walls; unavoidable openings such as doors and fixed glazed windows must have at least half the resistance period of the wall; doors must be self-closing and smoke-tight; and the surroundings of these half-resistance openings must be kept clear of all combustible materials.
The same paragraph also regulates service penetrations: where water, electrical, heating, ventilation and similar 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 fire wall (BYKHY Article 25(2)).
There is a separate article for electrical installations: in horizontal and vertical crossings from one fire separation to another, all openings must be closed with fire-stopping mortar, pillows, panels and similar materials (BYKHY Article 69).
For product selection, installation steps and site documentation, see the article on firestop applications; it contains a detailed table by penetration type.
Floors are fire walls too
An often-overlooked provision: all floors must have the character of a fire wall; the fire resistance periods of floors are given in Annex 3/B (BYKHY Article 26(1)). In other words, when the compartment discussion ends vertically, it continues horizontally.
Other provisions on the floor side:
- Floor finishes are made of at least normally flammable material, and in high-rise buildings of at least hardly flammable material (BYKHY Article 26(2)); easily flammable thermal insulation on a floor is permitted only if it is covered with a screed at least 2 cm thick (BYKHY Article 26(3)).
- Where services pass through a floor, the gap around them is sealed, leaving no opening, for at least the fire resistance period of the floor (BYKHY Article 26(5)).
Leapfrogging along the facade
Even if the compartment wall is never breached, flames can jump via the facade. The Regulation closes this route with a separate article: to prevent flames passing from one floor to another, a solid surface of fire-resisting facade element at least 100 cm high vertically is formed between unprotected openings such as the windows of two floors, or the facade is protected by an automatic sprinkler system with sprinklers placed on the inside of the facade at no more than 2 m spacing and no more than 1.5 m from the facade (BYKHY Article 27(1)). The same paragraph also sets the material class: external facades must be made of hardly combustible material in buildings with a building height of more than 28.50 m, and of at least hardly flammable material in other buildings.
Traditional facade systems have an additional rule: in buildings with a building height of more than 6.50 m, fire barriers of non-combustible material at least 15 cm wide at the sides and at least 30 cm wide at the top of windows and similar openings are formed (BYKHY Article 27(2)(b)).
In curtain walling, the critical detail is the slab edge: the junctions between facade elements and floors that have no gaps through which flames can pass are sealed, for the period that provides the floor's fire resistance, so as to prevent flames leaping to adjacent floors (BYKHY Article 27(3)(a)).
The roof side
The Regulation requires a series of possibilities to be considered in the construction of roofs: collapse of the roof, fire entering through the roof, spread under and within the roof, passage from a rooflight into the building, spread over the outer surface of the covering and flaming droplets, and fire passing to the neighbouring roof in adjoining buildings (BYKHY Article 28(1)).
The concrete requirements are in two paragraphs. Roof coverings must be of BROOF class materials, and the surface or insulation beneath roof coverings must be of at least hardly flammable materials; where non-combustible material is used as the roof covering, the underlying surface is permitted to be of at least normally flammable materials (BYKHY Article 28(2)). In high-rise buildings and adjoining structures, the floors on which roofs sit must act as horizontal fire stops, and the roof structure and roof coverings must be of non-combustible material (BYKHY Article 28(3)).
Continuity: a one-sentence rule
A single provision ties all these details together: for fire compartments to be effective, the fire resistance of the elements enclosing a compartment is also continuous at the junctions, and there can be no non-fire-resisting openings between compartments (BYKHY Article 24(7)).
The points on site where this sentence is violated are well known: the wall stopping above the suspended ceiling (Article 24(7)), unsealed service penetrations (Articles 25(2), 26(5), 69), openings made later (Article 25(2)), the gap between facade and floor (Article 27(3)(a)), missing facade protection between floors (Article 27(1)) and roof crossings in adjoining buildings (Articles 28(1)(f), 28(3)).
How this risk is managed during refurbishment is covered in the article on fire risk during refurbishment; periodic monitoring of penetrations is the subject of the inspection, testing and maintenance guide.
Sprinklers do not remove the separation
The notes to Annex 4 state that when suitable fire control systems are installed, the compartment area may be doubled or become unlimited (BYKHY Article 24(6)). The conditions of this flexibility are explained in the article on sprinklers and compartments. But a larger area does not mean the remaining boundaries are relaxed: as the number of compartments falls, the continuity rule of Article 24(7) and the prohibition of openings in Article 25(2) become even more critical.
Field note
During a site inspection of a wall separating two compartments in a production facility, the wall itself was flawless. When the suspended ceiling was opened, the wall was found to end at ceiling level; the void above turned the two compartments into a single volume. This is a direct violation of Article 24(7): there can be no non-fire-resisting openings between compartments.
The fault arises not from bad intent but from sequencing: the wall is built, the suspended ceiling is installed, and then nobody looks above the ceiling. Compartment inspection should therefore be carried out before the suspended ceiling is closed.
Checklist
- Have the compartment boundaries been conceived as an envelope matching the "on every side" definition in Article 4(tt)?
- Do the walls and floors of the spaces listed in Article 24(2) have the properties of a compartment wall?
- Have the resistance periods been taken from Annex 3/B and Annex 3/C? Does the boiler room comply with Article 54(2)?
- Are unavoidable openings at least half the wall's resistance period, self-closing and smoke-tight; have all service penetrations been sealed (Articles 25(2), 26(5), 69)?
- Has facade protection between floors been resolved as a 100 cm solid surface or facade sprinklers (Article 27(1))? In curtain walling, has the slab junction been sealed (Article 27(3)(a))?
- Do the roof covering and the underlying surface comply with Article 28(2)? Has Article 28(3) been applied for high-rise or adjoining buildings?
- Has compartment continuity been checked before the suspended ceiling is closed (Article 24(7))?
FAQ
How is a fire compartment defined in BYKHY?
A fire compartment is a zone within a building that is divided off, on every side including the ceiling and floor slabs, into smoke- and heat-tight areas by building elements with at least 60 minutes of fire resistance (BYKHY Article 4(tt)). A fire wall, by contrast, is a vertical element that stops the progress of a fire for a specified period where volumes with different fire loads must be separated (BYKHY Article 4(rr)).
Can a fire wall have a door or opening?
As a rule, there can be no holes or openings in fire walls. If openings such as doors and fixed glazed windows cannot be avoided, they must have fire resistance of at least half the resistance period of the fire wall. Doors must be self-closing and smoke-tight; the surroundings of these half-resistance openings are kept clear of all combustible materials (BYKHY Article 25(2)).
Can services pass through a fire wall?
They can, but sealing is mandatory. Where water, electrical, heating, ventilation and similar 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 fire wall (BYKHY Article 25(2)). The same rule applies at floor penetrations on the basis of the floor's resistance period (BYKHY Article 26(5)).
How is a fire wall dealt with at the roof?
In roof design, the Regulation requires the possibility of a fire on the roof passing to the neighbouring roof in adjoining buildings to be considered (BYKHY Article 28(1)(f)). In high-rise buildings and adjoining structures, the floors on which roofs sit must act as horizontal fire stops, and the roof structure and roof coverings must be of non-combustible material (BYKHY Article 28(3)).
References
- Turkish Regulation on Fire Protection of Buildings (BYKHY), Council of Ministers Decision No. 2007/12937 of 27/11/2007, Official Gazette 19/12/2007, No. 26735. Amendments: OG 09/09/2009-27344; OG 05/04/2012-28255; OG 09/07/2015-29411; Council of Ministers Decision No. 2017/10459 of 14/06/2017 (in force 29/06/2017); Council of Ministers Decision No. 2018/11347 of 05/02/2018 (in force 15/03/2018); OG 04/11/2020-31294 (Presidential Decision 3167); OG 20/11/2021-31665 (Presidential Decision 4825); OG 01/07/2025-32943 (Presidential Decision 10026). Current text: mevzuat.gov.tr (consolidated text)
- Articles used in this article: Article 4(rr) (fire wall), 4(tt) (fire compartment), Article 24(1) (Annex 3/B), 24(2) (spaces counted as compartment walls), 24(3) (common walls, semi-detached houses), 24(6) (Annex 4), 24(7) (continuity), Article 25(1) (adjoining buildings 90 minutes), 25(2) (no holes or openings, service penetrations), 25(3) (shaft walls and hatches in high-rise buildings), Articles 26(1)–26(5) (floors), Articles 27(1), 27(2)(b), 27(3)(a) (facades), Articles 28(1), 28(2), 28(3) (roofs), Article 29(7) with Annex 3/A, Annex 3/B, Annex 3/C, Article 54(2) (boiler room), Article 69 (electrical penetrations through fire separations).
- TS EN 13501-1 and TS EN 13501-5: the reaction-to-fire classification standards referenced in the Regulation for Annex 2/Ç and roof coverings.
All article numbers and values in this article are taken from the Regulation text published in the Official Gazette. Even so, the current text should be used as the basis for design, and the design should be carried out by an authorised engineer.
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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.