Under Article 4 of the Turkish Regulation on Fire Protection of Buildings (BYKHY), a high-rise building is a building whose building height exceeds 21.50 m and whose structure height exceeds 30.50 m. These two measures are taken from different points, and once the threshold is exceeded the provisions on compartments, facades, escape width, the fire brigade outlet line and pressurisation change.
Two different height definitions
The regulation defines two separate heights (BYKHY Article 4):
| Term | Definition (Article 4) | Measured from |
|---|---|---|
| Building height | The distance from the point at which the building takes its level to the eaves level, or the height set in the zoning plan and the regulation | Between the level point and the eaves |
| Structure height | The total height of all floors built, including basement floors, mezzanines and roof-space rooms | From the basement to the roof space |
| High-rise building | A building whose building height exceeds 21.50 m and whose structure height exceeds 30.50 m | Article 4(ccc) lists the two measures separated by a comma; the text contains no "and" or "or" conjunction |
The most common mistake in practice is looking at the wrong measure, either leaving out or counting the basement floors. The high-rise definition uses both measures; some articles, such as Article 89, refer directly to "structure height" or "stairwell height".
Provisions that change above the threshold
| Article | Threshold | Provision |
|---|---|---|
| Article 24(4) | Building height > 21.50 m (non-residential); > 30.50 m (residential) | On the floors above this height, at most three floors are arranged as one fire compartment |
| Article 27(1) | Building height > 28.50 m | External facade of low-flammability material; in other buildings at least hardly-ignitable |
| Article 33(2) | High-rise building | The width of escape routes and stairs may not be less than 120 cm |
| Article 94(1)(a)(1) | High-rise buildings; shopping centres, car parks and similar places with a floor area over 1,000 m² (including factories, workshops and warehouses) | Fire brigade connection outlets on a wet or dry fixed pipe; in protected spaces |
| Article 89(1) | Stairwell height > 30.50 m (except residential) | Pressurisation of escape stairs |
| Article 89(3) | Structure height > 51.50 m (residential) | Pressurisation of escape stairs |
| Article 34(7) | Emergency lift and structure height > 51.50 m | Fire lobby in front of the escape stair mandatory |
The automatic fire detection requirement is also tied to Annex 7 through structure height or total enclosed area (Article 75(3)): automatic detection is required if the structure height exceeds 51.50 m in residential buildings, or if the structure height exceeds 30.50 m or the total enclosed area exceeds 5,000 m² in office buildings. Here too the criterion is structure height, not the high-rise definition.
The facade threshold is 28.50 m, not 21.50 m
Article 27(1) uses a building height threshold of 28.50 m for external facade material. The same paragraph requires, to prevent flames passing from floor to floor, a solid fire-resisting surface at least 100 cm high vertically between the unprotected openings of two floors; as an alternative, it allows the facade to be protected by sprinkler heads on the inside of the facade at no more than 2 m spacing and no more than 1.5 m from the facade.
Field note
The decision "let's stay below 21.50 m" is often made on projects; however, since Article 24(4), Article 27 and Article 89 use separate thresholds, looking at a single number is not enough. In a residential project the compartment rule starts at 30.50 m and pressurisation at 51.50 m; in a non-residential project the compartment rule starts at 21.50 m and pressurisation at a 30.50 m stairwell. Check each threshold on a separate line.
Checklist
- Have the building height and the structure height been calculated separately (Article 4)?
- Has the residential / non-residential distinction been made (Article 24(4), Article 89)?
- If the building height is above 28.50 m, is the facade material low-flammability (Article 27)?
- In a high-rise building, has an escape route width of 120 cm been provided (Article 33(2))?
- Are the fire brigade outlet line connections in a protected space (Article 94(1)(a)(1))?
FAQ
How is a high-rise building defined under BYKHY?
Under BYKHY Article 4, a high-rise building is a building whose building height exceeds 21.50 m and whose structure height exceeds 30.50 m. Building height is the distance from the point at which the building takes its level to the eaves level; structure height is the total height of all floors, including basement floors, mezzanines and roof-space rooms.
Which provisions apply once the high-rise threshold is exceeded?
Article 24(4): in non-residential buildings with a building height over 21.50 m, at most three floors above this height form one fire compartment. Article 33(2): in high-rise buildings, the width of escape routes and stairs may not be less than 120 cm. Article 94(1)(a)(1): fire brigade outlet line connections are mandatory in high-rise buildings. Article 89 and Article 34(7) use the 30.50 m and 51.50 m thresholds.
Is there a separate height threshold for facades?
Yes. Under Article 27, the external facade must be of low-flammability material in buildings with a building height over 28.50 m, and of at least hardly-ignitable material in other buildings. This threshold differs from the 21.50 m in the high-rise definition.
References
- Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments; Articles 4, 24, 27, 33, 34, 75, 89, 94 and Annex 7. 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.