The space above a suspended ceiling is a second volume that is not drawn in the project but exists on site. The Turkish Regulation on Fire Protection of Buildings (BYKHY) ties this volume down in three places: Article 26(4) sets the material class, Article 87(7) the cables that may pass through it when it is used as a plenum, and Article 69 the sealing of penetrations between fire separations.
Suspended ceiling material: Article 26(4)
The sentence most often heard on site is: the ceiling is plasterboard anyway, it does not burn. The Regulation does not leave this to assumption. Under Article 26(4), the ceiling linings and suspended ceiling materials of all buildings other than detached single-family houses must be at least low flammability.
The code equivalent of the term is given in Annex 2/Ç; low flammability corresponds to the group of rows starting at B,C-s1,d0 and extending, at minimum, to A2,B,C-s3,d2. How the code is read is explained in detail in the reaction-to-fire classes of building materials article.
The critical distinction here is this: Article 26(4) governs the material's reaction to fire; it does not say that the ceiling is a fire-resisting separation. Fire resistance is a separate matter and is left to Article 29(7) and the Annex 3 tables. A decorative suspended ceiling, even if it is at least low flammability, is not a compartment boundary.
Compartment continuity: where does the wall stop
This is the most critical topic regarding suspended ceilings, and the Regulation states it clearly. Under Article 24(7), for fire compartments to be effective, the fire resistance of the elements enclosing the compartment is also continuous at the junctions, and there can be no non-fire-resisting openings between compartments.
In practice, partition walls often stop at suspended ceiling level. In that case the two compartments are connected to each other through the ceiling void, and the continuity required by Article 24(7) is missing. Why the compartment areas permitted by occupancy class differ so much is explained in the fire compartment areas article; none of those area limits means anything in a building where the wall is cut off above the ceiling.
On site, check three points: does the top of the wall continue up to the underside of the slab, have the gaps left above the wall because of slab beams or trapezoidal deck profiles been filled, and has every cable tray and pipe passing through the wall been sealed individually.
Provisions for sealing penetrations
Instead of piling penetration sealing into a single article, the Regulation distributes it according to the element being penetrated. The table below summarises which paragraph to cite for which penetration on site.
| Penetration | Regulation provision |
|---|---|
| Horizontal and vertical crossings of electrical installations between fire separations | Article 69: all openings are sealed with firestop mortar, pillows, boards and similar materials |
| Water, electrical, heating and ventilation services passing through a fire wall | Article 25(2): the area around the service is sealed, leaving no opening, for at least the fire resistance period of the fire wall |
| Services passing through a floor | Article 26(5): the area around the service is sealed, leaving no opening, for at least the fire resistance period of the floor |
| Normal-flammability soil pipe over 70 mm in a high-rise building | Article 29(4): fire stoppers at floor crossings rated for the fire resistance period of the compartment wall |
| Ventilation duct crossing a 120-minute compartment wall or floor | Article 87(8): ducts are in principle not to penetrate compartment walls; where the crossing is unavoidable, measures such as a fire damper, a shunt duct or a special collar at the crossing |
| Ventilation duct passing through a protected shaft | Article 87(8): fire dampers at entry to and exit from the shaft |
| One air handling unit serving more than one compartment | Article 87(6): fire dampers in the supply and extract ducts at crossings between compartments |
| Pressurisation ducts | Article 87(9): fire dampers are not used |
Article 87(11) further requires service shafts and ducts that play a role in fire spread to be aligned with the fire compartments and insulated so as not to reduce the fire resistance of the compartment, and does not permit ventilation ducts and shafts to cross compartments except with special details. The same paragraph requires air ducts to be made of, or lined with, non-combustible material; Article 87(4) requires duct lining material to be at least low flammability.
For typical mistakes on the installation side, see the firestop application guide article.
The plenum rule: Article 87(7)
This is the most overlooked provision regarding suspended ceilings and the one with the heaviest consequences. Under Article 87(7), where spaces such as the void above a suspended ceiling and below a raised floor are used as a plenum, only mineral-insulated, aluminium or copper armoured cables, rigid metal conduit and liquid-tight flexible metal conduit may pass through these spaces. The same paragraph permits the use of cables for computer, television, telephone and intercom systems, fire protection system pipes, and pipes of non-combustible material carrying non-flammable liquids.
The practical meaning is this: the decision to use the ceiling void for return air redefines every cable and pipe that will pass through that void. A plenum decision taken on the architectural or mechanical side directly binds the electrical design. If these two disciplines do not sit at the same table, non-compliance is inevitable.
For a more general view of fire behaviour in concealed spaces, see the raised floor fire spread article, and for passive protection of cable trays, the rock-wool insulation of cable trays article.
Cables that must keep working in a fire
The Regulation sets two separate expectations for cables, and one does not replace the other.
Fire resistance. Under Article 83(1), the following must be able to withstand fire for at least 60 minutes: signal and power cables running from fire control panels to audible and visual alarm devices, voice evacuation system amplifiers and loudspeakers, and emergency control devices; the parts inside the building of cables used to notify the fire brigade and firefighting teams; communication and power cables between main and sub fire control panels and repeater panels; and the power supply cables feeding all fire control panels and repeater panels. Article 83(2) requires these cables to be tested and certified in accordance with the relevant standards.
Article 83(3) defines an exemption: fire resistance may not be required for cables to manual call points, detectors and cables between panels, which do not need to keep working for long after a fire is detected, nor for cables to electromagnetic door holders and similar devices that do not create a hazardous situation when de-energised.
Halogen and toxic gas. Under Article 83(5), in healthcare buildings, accommodation buildings with more than 100 persons and assembly buildings with more than 1,000 occupants, the materials used in all supply and distribution cables and cable enclosures must be halogen-free and must not produce any toxic gas when exposed to fire.
Article 83(4) also requires fire alarm system cables to be installed separately from other systems and from power-carrying cables. In projects where trays are shared in the suspended ceiling void, this provision is a direct routing constraint.
Field note
In a shopping centre, the compartment walls had been drawn correctly in the project. On site, the walls were found to stop at suspended ceiling level, with a continuous cable tray running between two compartments. The continuity required by Article 24(7) was missing, and the penetration sealing required by Article 69 had not been done either; a single finding breached two separate provisions at once.
A second example: on an office floor, return air was taken through the suspended ceiling void, meaning the void was being used as a plenum. No one on the electrical design side was aware of this decision, and most of the cables in the void were outside the types permitted by Article 87(7). The problem surfaced not at handover but during a refurbishment in the second year of operation.
The lesson: the ceiling void is not a place to be closed once and forgotten, but a volume to be managed for the life of the building. Write the plenum decision on the project cover sheet, and record every sealed penetration with its location, date, system used and a photograph, then hand the records over to the operator. The chain of responsibility on the operator side is covered in the fire safety management article.
Checklist
- ☐ Certificate of at least low flammability obtained for the ceiling lining and suspended ceiling material (Article 26(4))
- ☐ Confirmed that partition walls continue up to the underside of the slab and that junctions are continuous (Article 24(7))
- ☐ Penetrations of electrical installations through separations sealed with firestop materials (Article 69)
- ☐ Fire wall and floor penetrations sealed for the fire resistance period of the element concerned (Article 25(2), Article 26(5))
- ☐ If the ceiling void is used as a plenum, the types of cables and pipes passing through it checked against the Article 87(7) list
- ☐ The plenum decision shown in the same way in the electrical, mechanical and architectural designs
- ☐ Dampers or equivalent measures applied at compartment crossings of ventilation ducts (Article 87(8))
- ☐ Confirmed that no fire dampers are used in pressurisation ducts (Article 87(9))
- ☐ Duct lining material documented as at least low flammability (Article 87(4))
- ☐ At least 60 minutes of fire resistance demonstrated by certificate for cables within the scope of Article 83(1)
- ☐ Halogen-free cable use confirmed in buildings within the scope of Article 83(5)
- ☐ Fire alarm cables installed separately from power cables (Article 83(4))
- ☐ Confirmed that no service shaft access panel opens into the escape stair enclosure or fire lobby (Article 41(9))
FAQ
What does BYKHY require for suspended ceiling material?
Under BYKHY Article 26(4), the ceiling linings and suspended ceiling materials of all buildings other than detached single-family houses must be at least low flammability. Annex 2/Ç gives the TS EN 13501-1 equivalent of low flammability as the group of rows starting at B,C-s1,d0 and extending, at minimum, to A2,B,C-s3,d2.
Which cables may pass through a suspended ceiling void used as a plenum?
Under BYKHY Article 87(7), where spaces such as the void above a suspended ceiling and below a raised floor are used as a plenum, only mineral-insulated, aluminium or copper armoured cables, rigid metal conduit and liquid-tight flexible metal conduit may pass through them. Cables for computer, television, telephone and intercom systems, fire protection system pipes and non-combustible pipes carrying non-flammable liquids are also permitted.
Must the compartment wall continue above the suspended ceiling?
Under BYKHY Article 24(7), for compartments to be effective, the fire resistance of the elements enclosing the compartment must also be continuous at the junctions, and there must be no non-fire-resisting openings between compartments. If the wall stops at suspended ceiling level, this continuity is not achieved.
How are cable penetrations sealed?
Under BYKHY Article 69, in all buildings and structures, at horizontal and vertical crossings of electrical installations from one fire separation to another, all openings must be sealed with firestop mortar, pillows, boards and similar materials to prevent the passage of fire or smoke.
References
- Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments; Articles 24(7), 25(2), 26(4), 26(5), 29(4), 29(7), 41(9), 69, 83(1)–83(5), 87(4), 87(6), 87(7), 87(8), 87(9), 87(11), Annex 2/Ç, Annex 3. Amendments: OG 09/09/2009-27344; OG 05/04/2012-28255; OG 09/07/2015-29411; Council of Ministers Decision 2017/10459 of 14/06/2017 (in force 29/06/2017); Council of Ministers Decision 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). mevzuat.gov.tr (consolidated text)
- TS EN 13501-1 – the classification standard on which the reaction-to-fire classes in Annex 2/Ç are based.
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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.