Fire safety and powder coating in high-rise buildings: A Guide

The relevant documents and sections are as follows: 

• Approved Document B (ADB), Volume 1: Dwellings (including flats)

Requirement B4 section 10 details “Resisting fire spread over external walls”. Page 81 – 88.

• Approved Document B (ADB), Volume 2: Buildings other than dwellings.

Requirement B4 section 12 details “Resisting fire spread over external walls”. Page 91 – 98.

• There is another, lesser-known Approved Document 7 (AD7). which details the compliance of materials and workmanship.

We will be cutting through the jargon and complexity to summarise the requirements of section B4  of ADB volumes 1 & 2 and Approved Document 7.

The first thing to point out is that the contents of volume 1 and 2 are almost the same. Between them they cover dwellings (including flats) and buildings other than dwellings. Therefore the points below cover every type of building, occupancy and usage. For ease we have simply referred to both volume 1 and volume 2 as “ADB – B4”.

ADB Requirement B4, External fire spread.

This states that the external walls of the building “shall adequately resist the spread of fire over walls…….” Note that it does not say that the external walls of the building should be fireproof. The document goes on to say that the “materials used to construct the external walls……do not contribute to the rate of fire spread up the outside of the building”.

Table 12.1 details the fire performance requirements of materials for various types of building. Any external surface which achieves a performance category better than A2-s1, d0 can be used on any building of any type and any height.

Therefore, in this regard, A2 rated materials are as compliant as A1 rated materials.

Approved Document 7, Materials and workmanship

Fitness of materials (in our case, powder coating material) is established via external testing results which are available to powder coaters from the powder manufacturers. This certification references standards fire performance standards BS EN ISO 1716, BS EN 13823 and BS EN 13501. Fire performance of powder coating is via 3rd party certification, an accredited fire test facility.

Other important powder coating standards and specifications; BS EN 12206-1, Qualicoat and BS EN 13438-1 do not mention fire performance of powder coatings.

The adequacy of Workmanship (applying the powder correctly) is established via certification to a recognised management system (ISO 9001-1 for example). Internal tests to demonstrate control and compliance to the ‘Field of Application’ of the powder coating material, as detailed in the powder manufacturers fire approval certificates is the best method to demonstrate workmanship.

Making your life simple

Conformance to fire regulations is not simple.There are many nuances around definitions of surface area, fabrication techniques, full height testing etc which need to be taken into account. We have not elaborated on those issues here.

We can, however, clarify the four actions required to meet ADB-B4 requirements and our suggested ways to clear up some of the common misconceptions that have arisen around the topic of fire safety compliance in building materials.

Four important actions

1. The powder coating material must have manufacturer 3rd party certification stating that it is  A2-s1, d0 compliant.
2. The powder manufacturer certification must include a “Field of application”. This is a description of the conditions under which the tests were performed.
3. The powder coating applicator MUST use the approved powder.
4. The powder coating applicator must demonstrate (via measurement of the powder coating thickness) that the application complies with the Field of Application.

Achieving points 1 and 2 satisfies ADB-B4 requirements

Achieving points 3 and 4 satisfies the materials and workmanship AD7 requirements.

Avoiding misunderstanding and confusion

• Consult with the Fire Officer or project consultant in good time to agree powder coat film thickness measurement criteria, Field of Application, design complexities and other requirements.
• Early discussion between client, fabricator, powder coater and architect is essential and will save time later.
• Include a requirement for written records of powder coating film thickness in your specification.
• Remember - powder coating is not flammable; it does not sustain a fire or accelerate a fire. Once the source of ignition is removed powder coating will cease to burn, it is the effect NOT the cause.
• A2 rating has the same compliance  as A1 rating is not better than A2
• Any powder coating finish claimingto be A1 will have been applied  too thinly to perform its primary functions of colour retention, gloss retention, adhesion and corrosion prevention.

LInks to the relevant documents