Facade Fire Safety and BYKHY Rules

The Turkish Regulation on Fire Protection of Buildings (BYKHY) gathers the core of its facade rules in Article 27; however, Article 27(4), added by the 2021 amendment, imposes a separate and stricter facade requirement in the external fire zone of certain facilities in or adjacent to forest areas, and Article 28(4) was added for roofs. As the general rule, under Article 27(1) external facades must be of limited-combustibility material in buildings with a building height of more than 28.50 m, and of at least low-flammability material in others. The same paragraph requires a solid surface at least 100 cm high vertically, or facade sprinklers, to stop floor-to-floor spread.

There are two separate facade thresholds; do not mix them up

The most common mistake on site is to tie the facade material question to the high-rise definition. These are two separate thresholds.

• High-rise definition (Article 4(ccc)): Buildings with a building height of more than 21.50 m or a structure height of more than 30.50 m. For the background to this threshold, see the 21.50 m high-rise threshold article.
• Facade material threshold (Article 27(1)): Building height of 28.50 m. This value is specific to Article 27 and is not the same as the high-rise definition.

Building height is defined in Article 4(h): 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. When making the facade decision, do not confuse this measure with structure height (Article 4(bbb)), which also includes basement floors.

Article 27(1): material and floor-to-floor barrier

Article 27(1) sets two separate requirements in a single paragraph.

Material. External facades must be of limited-combustibility material in buildings with a building height of more than 28.50 m, and of at least low-flammability material in other buildings. The code equivalents of the terms are in Annex 2/Ç: limited combustibility is A2-s1,d0; low flammability is the group of rows starting with B,C-s1,d0 and extending to, at minimum, A2,B,C-s3,d2. How to read the codes is explained in detail in the reaction-to-fire classes of building materials article.

Floor-to-floor barrier. To prevent flames passing from one floor to another, a solid surface of fire-resistant facade element at least 100 cm high vertically is formed between the unprotected openings, such as windows, of two floors. Alternatively, 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.

This second option is often overlooked in design. If the 100 cm solid surface cannot be provided for architectural reasons, the regulation leaves a way out, but that way out is not an ordinary sprinkler line: the sprinkler spacing and the distance to the facade are fixed by numbers in the paragraph.

Conventional facades and thermal insulation systems

Article 27(2) directly targets external thermal insulation systems, the most common facade solution in Turkey.

System certificate (27(2)(a)). Where a thermal insulation system made up of insulation material, adhesive, anchors, render mesh, render and similar components is applied, the system must be certified by an accredited laboratory under the relevant standards. The certified system details and technical properties are included in the placing-on-the-market documents. In other words, a certificate for the board alone is not enough; the certificate is for the assembled system.

Ground-level and window barriers (27(2)(b)). In buildings below 28.50 m in height whose external facade consists of low-flammability material or system, the first 1.5 m above natural or finished ground level must be clad with non-combustible material. 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 side edges and at least 30 cm wide at the top edge of windows and similar openings must be formed.

Read together, these two provisions address the two typical ignition scenarios of facade fires: ignition from outside at ground level, and flames breaking out of a window.

Height difference in adjoining buildings (27(2)(c)). In adjoining buildings of different heights, the external facade cladding of the taller building's storey at the roof level of the lower building must be of non-combustible material or system. A fire on the roof of the lower building applies heat and flame directly to the facade of the taller one; the provision targets exactly this contact zone.

Curtain walls: cavity and slab junction

Article 27(3) contains two provisions, both addressing risks specific to curtain walls.

Slab junction (27(3)(a)). The junctions between facade elements and floors that have no gaps through which flames can pass are sealed for the period that provides the fire resistance of the floor, so as to prevent flames leaping to adjacent floors. On site this means closing the gap between the facade and the slab edge; how installation details are selected is covered in the high-rise glass facade firestop and firestop installation guide articles.

Ventilated facade (27(3)(b)). The facade and insulation materials used in buildings with open-jointed or ventilated curtain wall systems must be at least limited combustibility. Note that this requirement is not tied to building height. The risk that the facade cavity behaves like a vertical chimney raises the material level regardless of height. How fire behaves in the facade cavity and the international test approaches are covered in the glass facade fire risk article.

Article 27(4): external fire zone for facilities in forest areas (2021)

The amendment published in Official Gazette No. 31665 of 20/11/2021 added a separate layer to the facade rules for a specific group of facilities. The scope has to be set correctly first:

• Article 7(12): For industrial facilities to be built in or adjacent to forest areas, such as refineries, fossil-fuel power plants, energy generation facilities with an installed capacity of 500 MW or more and factories with a total enclosed floor area greater than 2000 m², together with their storage facilities/yards, the additional measures specified in the regulation are taken.
• Article 21(5): In these areas, except for the exceptions listed in the paragraph, an external fire zone is formed within 100 m of the facility's building facade and storage yard; this distance is increased according to the terrain slope. Within the zone there are separate vegetation and combustible material rules for the bands of 1.5 m, 1.5–10 m, 10–30 m and 30–100 m from the building facade.

Facade (27(4)). In buildings to be constructed in the areas specified in Article 21(5), all external facades (including balconies, projections, chimneys, terraces and the like) must be of non-combustible material, door and window frames must be of non-combustible material and at least 30 minutes fire-resistant, and doors and windows must have at minimum double glazing, or the glass used must be unbreakable or 30 minutes fire-resistant. The external facades of annexes closer than 15 m to the building must also be of non-combustible material or at least 30 minutes fire-resistant. Where the relevant sections of the regulation define a higher criterion, those criteria are followed.

There is no height condition in 27(4): in these areas, the external facade is non-combustible whatever the building height. A limited-combustibility cladding that satisfies the general rule does not satisfy this paragraph; the Annex 2/Ç equivalent of non-combustible is given in the reaction-to-fire classes of building materials article.

Existing buildings (138(5)). For buildings within the scope of Article 7(12) that were completed or under construction before the paragraph entered into force, the measures to be taken within the plot boundaries are applied (except for external fire zone measures whose distances the authority determines cannot be met because of the location); in these buildings, at least limited-combustibility material may be used instead of the non-combustible material specified in Articles 27(4) and 28(4) (BYKHY Article 138(5)).

The facade decision also affects the compartment decision

The facade is the surface through which the compartment logic is breached from outside. The regulation establishes this relationship in two places. Under Article 24(4), in non-residential buildings with a building height of more than 21.50 m and residential buildings with a building height of more than 30.50 m, at most three storeys are arranged as one fire compartment on the floors above those heights. Article 24(7) requires the fire resistance of the elements enclosing the compartment to be continuous at the junctions as well, and allows no openings without fire resistance between compartments. The facade-to-slab junction is exactly such a junction. How compartment areas vary by use class is covered in the fire compartment areas article.

In adjoining buildings, Article 25(1) comes into play: fire walls separating adjoining buildings are designed with at least 90 minutes of fire resistance, and the same paragraph states that the properties fire walls must have at facades and roofs are set out in the relevant articles.

The roof is also a continuation of the facade. Under Article 28(2), roof coverings must be of B_ROOF class materials and the surface or insulation beneath them of at least low-flammability material; where non-combustible material is used as the roof covering, the underlying surface may be at least normal flammability. Under Article 28(3), in high-rise buildings and adjoining buildings, the roof structure and roof coverings must be of non-combustible material. Under Article 28(4), added in 2021, in buildings to be constructed in the areas specified in Article 21(5) (external fire zone), roof coverings, materials such as roof valleys, chimney flashings, gutters and downpipes, and the roof structure must be of non-combustible material, and the surface or insulation beneath the roof coverings of at least limited-combustibility material (Added: OG 20/11/2021-31665).

Field note

In an office building, the correct class had been chosen for the facade cladding and the documents were complete. However, the backfill of the sill and reveal profiles at the window edges appeared in no document. Article 27(2)(b) requires a non-combustible barrier at least 15 cm wide at the side edges and at least 30 cm wide at the top edge of window openings in buildings with a building height above 6.50 m. That barrier covers exactly the zone where those profiles sit; when the backfill is not questioned, the barrier stays on paper.

A second example: on a ventilated curtain wall, the cladding panel was of the correct class, but the substructure was timber battens. Article 27(3)(b) requires facade and insulation materials to be at least limited combustibility, and the inside of the facade cavity is exactly the volume this paragraph seeks to protect.

The lesson: look for the combustible load on a facade not in the cladding panel but in the intermediate layers nobody looks at. Split the material list into cladding, insulation, substructure, sealing, backfill and fixings, and ask for a separate document for each line.

Checklist

• ☐ Building height measured according to the Article 4(h) definition and the facade class set against the 28.50 m threshold
• ☐ The Annex 2/Ç code for the facade material written into the specification
• ☐ Solid surface at least 100 cm high vertically between floors shown in the design
• ☐ If facade sprinklers were chosen instead of the solid surface, sprinkler spacing and distance to the facade checked
• ☐ Accredited laboratory certificate and system detail for the thermal insulation system filed
• ☐ The first 1.5 m above ground level seen to be clad with non-combustible material
• ☐ Non-combustible window barriers of 15 cm at the side edges and 30 cm at the top edge measured on site
• ☐ In adjoining buildings, the taller building's facade at the roof level of the lower building checked
• ☐ In curtain walls, the slab junction sealed for the floor's fire resistance period
• ☐ In open-jointed or ventilated facades, all facade and insulation materials selected as at least limited combustibility
• ☐ Sealed slab-edge gaps recorded with location and photographs
• ☐ Whether the facility falls under Article 7(12) (in or adjacent to a forest area) and the Article 21(5) external fire zone determined; if in the zone, facade, frames, glazing and annexes selected per Article 27(4) and the roof per Article 28(4) (Article 138(5) for existing buildings)

FAQ

Which reaction-to-fire class does BYKHY require for facade cladding?

Under BYKHY Article 27(1), external facades must be of limited-combustibility material in buildings with a building height of more than 28.50 m, and of at least low-flammability material in other buildings. Under Annex 2/Ç, limited combustibility corresponds to A2-s1,d0. This threshold is separate from, and independent of, the 21.50 m threshold in the high-rise definition.

How is the floor-to-floor spread barrier defined in BYKHY?

Article 27(1) requires a solid surface of fire-resistant facade element at least 100 cm high vertically between the unprotected openings, such as windows, of two floors to prevent flames passing from one floor to another. Alternatively, it allows the facade to be protected by automatic 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.

Where is the fire barrier placed in an external thermal insulation (ETICS) system?

Under Article 27(2)(b), in buildings below 28.50 m in height whose external facade consists of low-flammability material or system, the first 1.5 m above natural or finished ground level is clad with non-combustible material. 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 side edges and at least 30 cm wide at the top edge of windows and similar openings are formed.

Does the material class change for a ventilated curtain wall?

Yes. Under Article 27(3)(b), the facade and insulation materials used in buildings with open-jointed or ventilated curtain wall systems must be at least limited combustibility. This requirement is not tied to building height; it arises from the system type because of the risk that the facade cavity behaves like a chimney.

References

1. Turkish Regulation on Fire Protection of Buildings (BYKHY), Official Gazette 19.12.2007/26735 and amendments (including OG 20/11/2021-31665); Articles 4(h), 4(bbb), 4(ccc), 7(12), 21(5), 24(4), 24(7), 25(1), 27(1), 27(2), 27(3), 27(4), 28(2), 28(3), 28(4), 138(5), Annex 2/Ç. mevzuat.gov.tr (consolidated text)
2. TS EN 13501-1: the classification standard on which the facade material classes in Annex 2/Ç are based.
3. TS EN 13501-5: the standard referenced in Annex 2/Ç for the external fire performance class of roof coverings.

This article is for general information. For article numbers, thresholds and exemptions, the current regulation and standard texts published in the Official Gazette should be used, and design should be carried out by an authorised engineer.

SprinkCalc — Fire Sprinkler Design Across Three Standards

SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report.

Download SprinkCalc on the App Store

MEP Calc — 110+ Engineering Calculators

MEP Calc bundles 110+ engineering modules in one iOS app: 21 fire calculations plus heating, cooling, HVAC, plumbing, steam and natural gas.

Download MEP Calc on the App Store