Facade Standards: Key Russian SP Codes and GOST Standards

Facade regulations in Russia are a set of federal laws, codes of practice (SP) and standards (GOST) that set requirements for safety, fire protection, strength and thermal protection of facades, and for how work is carried out and accepted. There is no single 'facade law': the requirements are spread across documents in different fields.

For the client and designer, the key is to understand which document covers which issue: fire safety determines the permitted materials and systems, load codes govern fixing calculations, thermal protection determines insulation thickness, and rules for execution of works govern installation and acceptance. The current editions of documents must be checked as of the design date.

This article is for architects, designers, technical supervision and general contractors. Related material is in Facade maintenance, codes and repair.

Key documents on which facade design and construction are based:

Rainscreen facade systems additionally require a document confirming the system's suitability for use in construction: a technical assessment with a manual of technical details. The editions of codes are updated regularly, so the design specifies the current edition.

Besides the main documents, related codes and standards are used in facade design and construction:

In the absence of a dedicated national code for glass fibre reinforced concrete (GFRC) products, manufacturers usually rely on their own technical specifications and procedures, with test methods taken from concrete standards; internationally, the European standards EN 1169 and EN 1170 are used for GFRC. The list of documents for a specific project is fixed in the design.

Fire safety is the main constraint when choosing a facade system, especially for multi-storey and public buildings.

• Structural fire hazard class (K0–K3). For the outer side of external walls, the codes set the required class depending on the fire resistance degree and the structural fire hazard class of the building. High-rise and many public buildings require K0: the construction must not spread fire.

• Confirming the class. The class of a facade system is determined by fire testing a mock-up to Russian standard GOST 31251; the whole system is tested: cladding, substructure, insulation, wind barrier.

• Combustibility of materials. The combustibility group of the cladding and insulation (NG, G1–G4) is determined by combustibility tests. Rainscreens on taller buildings use non-combustible insulation and cladding.

• Details. Fire barriers in the ventilated cavity and non-combustible opening surrounds follow the system's technical details.

GFRC is a mineral material; according to manufacturers, including TECHNOFORMA Group, it belongs to combustibility class NG (non-combustible). The class of a specific system is confirmed by documents for the assembled system.

How often-confused terms relate to each other:

Hence a practical rule: non-combustible cladding does not automatically make a system K0. If there is combustible insulation, a combustible membrane or incorrectly installed fire barriers behind it, the system may fail the test. So technical supervision checks not only the certificate for the slab but also that the installed system matches the tested build-up, including the insulation brand, membrane, fire barrier spacing and opening surrounds.

The substructure and cladding fixings are calculated for a combination of loads according to Russian standard SP 20.13330:

• Dead load of cladding, rails and insulation; decisive for heavy materials (stone, GFRC, concrete panels).

• Wind load: pressure and suction; depends on the wind region, terrain type, height and facade zone. At corners and parapets peak suction is higher, and fixing spacing is reduced there.

• Snow and ice loads for canopies, cornices and horizontal elements.

• Thermal actions: expansion of rails, accommodated by movable connections.

• Seismic loads in seismic areas, according to SP 14.13330.

The capacity of anchors in the actual substrate is confirmed by on-site pull-out tests; the design value is taken from their results with safety factors. Test results are included in the as-built documentation.

The calculation procedure for a rainscreen facade in outline: determine the wind region and terrain type according to SP 20.13330, find the characteristic wind pressure for each facade zone taking into account height and aerodynamic coefficients (higher in corner zones and at parapets), add the dead load of cladding and substructure and, where necessary, snow, ice and seismic loads. Then check the strength and deflection of the rails and the capacity of brackets, clips, rivets and anchors. The result is bracket and rail spacing for each zone, the type and number of anchors, and testing requirements.

Thermal protection of external walls is governed by Russian standard SP 50.13330 'Thermal performance of buildings'. It sets:

• the required thermal resistance of walls depending on the heating degree-days of the construction area and the building's use;

• accounting for non-uniformities (brackets, anchors, reveals, junctions) through the reduced thermal resistance;

• requirements for protecting the envelope from excessive moisture;

• sanitary and hygienic requirements for internal surface temperature.

For a rainscreen this means the insulation thickness is chosen not by a 'standard 100 mm' but by calculation for the specific region, taking into account the thermally conductive inclusions of the substructure. Brackets are installed with thermal break pads, and the insulation is laid without gaps. More on this in the article on facade energy efficiency.

Besides thermal resistance, moisture requirements matter for rainscreens: the insulation must release moisture into the ventilated cavity, and the cavity must work as a channel with an inlet at the plinth and an outlet below the parapet. Cavity dimensions and the area of ventilation openings are set by the system's technical details. A breather membrane, if used, must be vapour-permeable and permitted by fire requirements for a building of that height.

A thermal calculation that accounts for brackets usually shows that the conductive inclusions of the substructure reduce the reduced thermal resistance noticeably, and the insulation thickness has to be increased. So brackets with a smaller cross-section, thermal break pads and optimal spacing are not only a way to save metal but also a way to meet thermal requirements without excess insulation thickness.

Quality control of facade work has several levels:

1. Incoming inspection of materials: checking data sheets, certificates, compliance with the design, appearance and geometry.

2. Operational control: setting out, installation of anchors, brackets, rails, insulation and cladding with tolerance checks.

3. Inspection of concealed work: anchoring, insulation, wind barrier and substructure before they are covered by cladding, with formal records.

4. Testing: anchor pull-out and, where necessary, checking tightening and strength.

5. Acceptance: checking facade geometry, joints, junctions and completeness of as-built documentation.

On capital construction projects, control is carried out by the contractor and the technical client (construction control), and on projects subject to state construction supervision, also by the supervisory authorities. Geometric tolerances and the set of documentation are determined by the design and the codes for execution of works.

What is checked at acceptance of a rainscreen facade: a summary checklist for technical supervision:

Typical comments at acceptance: no concealed work records for a substructure already covered by cladding; insulation or membrane replaced with an 'equivalent' without confirmation that the system was tested with it; anchors installed without tests in the actual substrate; incorrect bracket spacing in corner zones; ventilation gaps sealed with sealant. All of these are easier to prevent than to correct: checking the substructure means removing the cladding.

After acceptance, the regulations continue to apply in service: the owner must keep the facade in good condition and carry out inspections and repairs. For this, the facility manager is given the as-built documentation, cladding layout drawings and fixing details.

TECHNOFORMA Group designs facades with a team of 12 designers led by two architects and installs rainscreen substructures, insulation and cladding. Examples of projects where the company was responsible for design and installation:

• Chechen State University in Grozny: a public building, 12,000 m² of GFRC; design and installation supervision.

• RUBLEVO BUSINESS PARK in Moscow: 12 storeys, 15,000 m² of GFRC and 5,000 m² of FRONTEK.

All projects are in the TECHNOFORMA projects section. How thermal protection standards affect heating costs is discussed in Facade energy efficiency and building heat loss.