Standards for precast concrete

BS 8297

Code of practice: Design, manufacture and installation of architectural precast concrete cladding

BS 8297 has long been the definitive standard for precast concrete cladding. In October 2017, following recent advances and innovations in the sector, a new updated version was published, with a new title: ‘Design, manufacture and installation of architectural precast concrete cladding’. The standard has been revised to account for changes in manufacturing techniques and product ranges introduced over the last 20 years.
The new standard provides comprehensive coverage of all types of precast cladding and architectural concrete elements of the outer skin of the building.

BS 8297 should be used by anyone involved with designing, reviewing and installing architectural precast concrete, because it thoroughly explains the processes, considerations and best practice. It is as valid for architects and principal contractors as it is for structural engineers, and also other members of a project team, including façade consultants, designers, manufacturers and installers.

The standard is available from BSI.

Precast Concrete: EN 13369 and Precast Products    

With the exception of EN 13369, all structural precast product standards are mandated. However the product standards all refer to EN 13369: Common rules for precast concrete products. And thanks to EN 13369, the product standards are all structured in the same way.

The product standards (see table) are written 'by exception' to EN 13369 i.e. they either accept what is in EN 13369 or have mirror clauses that elucidate or supersede those in EN 13369. 

This approach was chosen in order to ensure that:

• The product standards are all based on a uniform approach. 
• Conflicting statements were avoided - a possibility that could not be entirely ruled out in the early phase of the standardisation work. Having been established in EN 13369, the higher-ranking provisions in the various product standards, should not differ from each other. 

As an example, in regard to 'mechanical resistance' EN 13369 Cl 4.3.3 says to either design to EN 1992, use design based on EN 1992 aided by physical testing or test. BS EN 1168 hollow core slabs Cl 4.3.3.2 goes into some depth concerning design but says nothing about 'verification' based on EN 1992 aided by physical testing or testing.

Structure of the product standards

The most important chapters refer to:

• the areas of application 
• the requirements made on: materials, manufacture and end product in particular, manufacturing tolerances, minimum dimensions, concrete cover, surface quality and the resistance to mechanical actions, ie the load-bearing capacity.  

Other clauses deal with:

• fire resistance, 
• behaviour in fire, 
• sound insulation, 
• durability, 
• safety in transport and during erection and 
• safety in use.  

One chapter is devoted to:

• test procedures, 
• conformity assessment, 
• labelling and 
• technical documentation. 

For most clauses, reference is simply made to EN 13369.  In other cases, the product standard defines appropriate rules, depending on the product characteristics. This is followed by normative and informative annexes, which also depend on the individual product.