Article 24(5) of the Turkish Regulation on Fire Protection of Buildings (BYKHY) permits atrium spaces only in buildings with low and medium hazard uses, and requires the atrium area to be no less than 90 m² at any point. Atrium voids smaller than 90 m² need a smoke curtain at least 45 cm deep on every floor and, in sprinklered buildings, sprinklers 15 to 30 cm from the curtain at no more than 2 m spacing; smoke control in atria is provided by natural or mechanical means.
Atrium definition (Article 4)
The regulation defines an atrium as a covered, large and tall volume into which two or more floors open, excluding stairwells, lift shafts, escalator openings, and water, electrical, ventilation, air-conditioning and communication service risers and shafts (BYKHY Article 4(g)).
The rules of Article 24(5)
| Rule | Value | Note |
|---|---|---|
| Buildings where an atrium is allowed | Only uses in the low and medium hazard classes | No atrium in high hazard uses |
| Minimum atrium area | Must not be less than 90 m² at any point | |
| Void smaller than 90 m² | Smoke curtain at least 45 cm deep on every floor | Along the perimeter of the void |
| Next to the curtain in a sprinklered building | Sprinklers 15 to 30 cm from the curtain, spaced no more than 2 m apart | |
| Smoke control | Provided by natural or mechanical means | Method set by the design |
The occupant load table in Annex 5/A gives a factor of 3 m² per person for an atrium floor (row 6: reception areas, waiting areas, atrium floor). According to the Annex 5/A note, the occupant load for this row is calculated on the gross area; this value is used in the escape calculation (BYKHY Article 32(1)).
Design impact
If the atrium area is 90 m² or more, the smoke curtain requirement does not arise, but natural or mechanical smoke control is needed in every case. If the area is below 90 m², a 45 cm curtain is added on every floor, plus curtain-line sprinklers in a sprinklered building. This difference has a cost and visual impact in small gallery voids; enlarging the void to 90 m² is a frequently chosen architectural decision.
Field note
The curtain-line sprinkler rule (15 to 30 cm distance, no more than 2 m spacing) is the detail most often missed on site; a standard ceiling sprinkler layout does not satisfy this line automatically, so a separate run should be planned around the curtain.
Checklist
- Is the building use in the low or medium hazard class?
- Is the atrium area 90 m² or more at every point?
- If smaller, has a 45 cm smoke curtain been designed on every floor?
- In a sprinklered building, are the curtain-line sprinklers placed 15–30 cm away and no more than 2 m apart?
- Has natural or mechanical smoke control been designed?
FAQ
What is the minimum atrium area under BYKHY?
Under Article 24(5), the area of an atrium must not be less than 90 m² at any point. Atria are only permitted in buildings whose uses fall in the low and medium hazard classes.
What is required for an atrium smaller than 90 m²?
Under Article 24(5), the perimeter of an atrium void smaller than 90 m² is enclosed on every floor by a smoke curtain at least 45 cm deep; in sprinklered buildings, sprinklers are placed 15 to 30 cm from the curtain with no more than 2 m between them.
Is smoke control mandatory in an atrium?
Yes. According to the last sentence of Article 24(5), smoke control in atria is provided by natural or mechanical means.
References
- Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments; Articles 4(g), 24(5), 32(1), Annex 5/A. 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.