The Grenfell Tower inquiry asked Claude Schmidt, president of cladding manufacturer Arconic, why he didn’t “seek to understand thoroughly the testing and certification which supported that product?” He replied: “Because it wasn’t my priority.”

This highlights why timber suppliers and contractors must understand the documents behind fire retardant timber. Only then can you be sure it’s fit for your purpose.


Many timber treaters provide customers with a classification report. Whilst not wrong, it’s open to interpretation and doesn’t assure you of effective fire protection for your specific application.

To create the report, a testing house assesses timber samples. But the field of application remains vague. The class of fire-treated timber might be Euro B or C, but is that sufficient for your assurance?

In contrast, a certification delivers more realistic assurance. At the core is a Constancy of Performance, supplied annually after auditing by a notified body. Species specific, certification also considers your end-use application. It provides in-depth information that demonstrates your safety testing.

In other words, your fire retardant timber is effectively specified, and you’ve done the right thing. You’ve understood the testing and certification process and made it your priority.

Certification comes from CE-marking – compulsory for fire retardant timber. Following Brexit, the UK is moving to a UKCA mark.


The Construction Product Regulation (EU number 305/2011) determines requirement for CE and UKCA marks. This states the manufacturer or company placing the product on the market must mark it.

For fire retardant timber, this isn’t clear. Is it the timber supplier? Or is it the company undertaking the treatment? After all, treating timber changes the properties considerably – akin to manufacturing.

We believe ‘the manufacturer’ is the timber treater. We provide all CE and UKCA documentation for our Burnblock fire retardant products.

As a timber supplier or contractor, understand who is responsible for CE and UKCA marking in your supply chain.


A CE or UKCA certification mark requires many documents. To ensure your fire retardant timber is fit for your purpose, understand them, and keep copies.

1. Constancy of Performance (AVCP1). Taking timber cladding as an example, CE marking uses the harmonised standard BS EN 14915:2013. This states the AVCP (Assessment and Verification of Constancy of Performance) must be Class 1 for reaction to fire products. 

AVCP1 requires annual auditing by a notified body. They then provide a Constancy of Performance. This document ensures a consistent standard of treatment – not a one-off sample of timber.

2. Declaration of Performance. A species-specific Declaration of Performance is crucial. Otherwise, you’ve got a vague promise. It’s only provided following the Constancy of Performance.

We provide this for every fire-treated product. We don’t have to, but we think it’s right. Your timber specification determines the type of fire retardancy treatment necessary.

3. Treatment Certificate. Provided by your timber treater, the certificate should detail the timber species being treated and the fire classification it will achieve (Euro B or C). It should also confirm treatment to correct standard (for example, EN 13501-1:2018).


When it comes to fire retardant timber, understanding certification is fundamental to construction safety. Specified and tested correctly, with assurance documentation, your timber will be fit for purpose and perform as expected if put to the test.