About the ISO TS 17870-3 porcelain cladding standard

As technical lead for the new international porcelain cladding standard, ISO TS 17870-3, recently published by BSI, our Founder and Chief Executive, Brian G Newell MBE, explains what it means for porcelain facade specification best practice.

The new ISO TS 17870-3 standard for porcelain facades, aims to enhance safety and quality assurance for porcelain cladding installations, and to enhance porcelain facade performance by reducing the potential for installation errors on site. The document applies to all mechanically-fixed porcelain cladding systems.

The International Standards Organisation is a global standards body representing more than 160 member nations that provide the vast knowledge and technical experience necessary to draft meaningful standards.

Our recent features on the ISO TS 17870-3 standard for porcelain cladding, including articles in Building Design , Construction Management and Project Scotland magazines, discuss the key elements of the new porcelain cladding standard. We would recommend that all architects, facade engineers and contractors delivering design & build contracts read the new porcelain facade standard in full, however, this summary provides an overview of the new requirements for porcelain cladding manufacturing, specification and installation.

Installation ready porcelain facade panels

To prevent the risk of poor fabrication practices and on-site fabrication issues, the ISO TS 17870-3 standard requires that all porcelain facade systems are supplied as installation-ready porcelain cladding panels, with no drilling or fitting of undercut anchors or attached bracketry on site. Ideally, on-site cutting of porcelain facade panels should also be avoided or minimised. The porcelain facade standard requires all drilling and fitting of undercut anchors, brackets or straps etc. to be carried out in quality-controlled and appropriately accredited factory facilities.

Meshing and combustibility of porcelain cladding systems

It is common best practice for facade manufacturers to apply an anti-fragmentation mesh to the rear face of porcelain cladding panels. While the standard does not make safety meshing mandatory, it does stipulate that any meshing used on porcelain facade panels should be A1 or A2-s1 d0 compliant to BS 13501-1. As porcelain is usually A1 rated for non-combustibility, this ensures that all ISO TS 17870-3-compliant porcelain facade systems are suitable for residential buildings taller than 18m.

For edge-slotted porcelain cladding systems, the standard recommends that the remaining front and rear edges of the slot walls should be a minimum of 5mm thick. It also recommends that this type of fixing should be avoided for very large porcelain facade panels.

Visible overlapping clip systems are also not considered appropriate for very large porcelain facade panels.

Durability and impact resistance of porcelain facade systems

Large format porcelain cladding panels should be proven to resist hard and soft body impact testing.

All fixing components for porcelain facade systems should have a high level of corrosion resistance, enabling them to retain their properties with little or no maintenance during the lifespan of the facade.