Short answer: Under BYKHY Article 89, pressurisation is mandatory in all buildings except residential ones where the stairwell height exceeds 30.50 m (89(1)), in escape stairs serving the basement in buildings with more than 4 basement floors (89(2)), and in residential buildings with a structure height above 51.50 m (89(3)). Emergency lift shafts are also pressurised (89(4)).

Article 89 of the Turkish Regulation on Fire Protection of Buildings (BYKHY) ties the pressurisation of escape stairs to three thresholds: in all buildings except residential ones, if the stairwell height exceeds 30.50 m; in stairs serving the basement if there are more than 4 basement floors; and in residential buildings with a structure height above 51.50 m. The same article also gives performance values such as a 50 Pa pressure difference, a 110 N door force and a 1 m/s air velocity.

Three thresholds and their basis

Threshold Paragraph Scope
Stairwell height > 30.50 m Article 89(1) All buildings except residential
More than 4 basement floors Article 89(2) Escape stairs serving the basement floors
Structure height > 51.50 m Article 89(3) Residential buildings
Emergency lift shaft Article 89(4) The shaft is pressurised so that it is not affected by the fire

The second sentence of Article 89(1) carries an important detail: even if the escape stair serving the basement and the upper floors is in the same shaft, if it is separated at ground level by a smoke-tight wall with 120 minutes fire resistance and a separate exit is provided, the height of the upper floors is taken as the basis for the stairwell.

Performance criteria

Criterion Value Paragraph
Pressure difference, all doors closed At least 50 Pa Article 89(5)
Pressure difference, open door condition At least 15 Pa Article 89(5)
If the fire lobby is also pressurised Pressure on the stair side higher than in the lobby Article 89(6)
Force applied to the door handle At most 110 N Article 89(7)
Average air velocity through an open door At least 1 m/s (with each door fully open) Article 89(8)
Design scenario At least 2 internal doors + 1 external discharge door open; leakage areas are added; the number of open doors is increased according to the number of floors Article 89(9)
Air quantity Covers the flows to the surroundings through leakage areas Article 89(10)
Overpressure protection Systems such as an overpressure relief damper and a variable-frequency fan are provided Article 89(11)

Under Article 89(8), the air velocity is provided for the condition where the doors of two consecutive floors and the external discharge door are fully open.

Design impact

Building Measure Pressurisation
Non-residential, stairwell 28 m < 30.50 m Not mandatory under Article 89(1)
Non-residential, stairwell 35 m > 30.50 m Mandatory (Article 89(1))
Residential, structure height 45 m < 51.50 m Not mandatory under Article 89(3); however, under Article 48(5)(c), at least one of the two protected escape stairs needs a fire lobby or pressurisation
Residential, structure height 54 m > 51.50 m Mandatory (Article 89(3))
Any building, 5 basement floors More than 4 Basement stairs mandatory (Article 89(2))

Field note

The two most common mistakes: "4 basement floors" is confused with "more than 4" (Article 89(2) requires a number exceeding four), and in a non-residential building the structure height is taken as the measure (Article 89(1) is based on the stairwell height). Systems such as an overpressure relief damper and a variable-frequency fan are not optional but mandatory under Article 89(11); if 50 Pa and 110 N cannot both be achieved during commissioning, first check the setting of these systems and the tightness of the doors.

Checklist

FAQ

In which buildings is escape stair pressurisation mandatory?

Under BYKHY Article 89, pressurisation is mandatory in all buildings except residential ones where the stairwell height exceeds 30.50 m (89(1)), in escape stairs serving the basement in buildings with more than 4 basement floors (89(2)), and in residential buildings with a structure height above 51.50 m (89(3)). Emergency lift shafts are also pressurised (89(4)).

What pressure difference and door force are required for pressurisation?

Article 89(5): with all doors closed, the pressure difference between the stairwell and the building use areas must be at least 50 Pa, and at least 15 Pa in the open door condition. Article 89(7): the force applied to the handle to open the door must not exceed 110 Newtons. Article 89(8): the average air velocity through an open door must be at least 1 m/s.

How many doors are assumed open in the design?

Under Article 89(9), the design assumes at least 2 internal doors and 1 external discharge door open, with the leakage areas of the closed doors added; the number of open internal doors is increased according to the number of floors in the building.

References

  1. Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments; Articles 48(5), 89. mevzuat.gov.tr

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Sources & Disclaimer

Sources 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.