Fire Performance Standards
1. What are Euroclasses and why are they replacing the old Class 1 / Class 0 standards?
Under the Construction Products Regulation introduced in July 2013 there is a move towards the European harmonisation of Standards for the fire retardant treatment of timber and plywood, with Euroclass B and Euroclass C replacing the old standards Class 0 and Class 1 respectively.
To achieve either a Euroclass B or C Specification, timber/plywood is tested to EN 13823:2002 (SBI or Single Burning Item Test) and EN ISO 11925 (Ignitability Test).
The SBI test is key and records parameters relating to the rate of fire growth, flame spread, heat release and smoke emission.
These test results are assessed in accordance with EN 13501-1 (Fire Classification of Construction Products and Building Elements) taking into account the presence or absence of an air gap behind the treated material and the fire characteristics of backing materials and a Euroclass Classification is assigned accordingly.
The same set of tests are conducted for both a Euroclass B and Euroclass C fire performance. However the thresholds for compliance in relation to SBI criteria are more stringent for Euroclass B than for Euroclass C. Therefore, by definition, if timber/plywood conforms to Euroclass B then it also conforms to Euroclass C.
In England and Wales, the fire requirements for buildings are dealt with by Approved Document Part B to the Building Regulations.
For timber and plywood in permanent construction, Euroclass B has now replaced Class 0 and Euroclass C has now replaced Class 1.
PLEASE NOTE: It is not possible to treat to a National Class and sell as a European Class or vice versa. For instance, timber treated to Class 0 cannot be sold as Euroclass B.
2. How many new Euroclass Classifications are there for fire performance and which are relevant to timber?
There are seven Euroclass Classifications for fire performance of different construction materials ranging from A1 & A2 through to F. Classifications for timber include B, C, D & E. Euroclasses D & E relate to untreated timber. Fire retardant impregnation to timber / plywood can elevate timber from Euroclass D (essentially untreated) to Euroclass C or Euroclass B to give the material in question compliance with the requirements of UK Building Regulations depending upon the location of the material within the building.
3. Are Euroclasses as good as the old Class 1 / Class 0?
The simple answer is that Euroclasses are underpinned by more up-to-date test methods compared to the old British Standards and trying to compare old and new is the wrong approach. Class 1 involved a measure of the Surface Spread of Flame (SSF). Class 0 included a measure of SSF and heat release. The Euroclass SBI test measures a wider scope of fire critical factors than the old Class 1 /0 tests, namely heat release, fire growth rate, smoke levels and flaming droplets. Euroclasses are more robust.
4. Building Control want evidence that the fire treated timber / plywood I am supplying will be Euroclass B / Euroclass C compliant. What documentation do I need?
Lonza Wood Protection issues a Fire Treatment Certificate upon despatch of an order which itemises customer name and order details. Generally this is what is presented to Building Control.
However, our recommendation is that a species/thickness specific Euroclass Classification Report, issued by UK independent fire test house such as Exova Warrington Fire, is also requested from the treater of the timber / plywood.
FULL COMPLIANCE = TREATMENT CERTIFICATE + CLASSIFICATION REPORT
5. Can I achieve 30 or 60 minute fire resistance with DRICON and ATP Generic?
In short no.
We offer fire retardant impregnation treatments that upgrade the fire performance of timber to achieve either a Euroclass B or Euroclass C fire performance.
Euroclass compliant timber retards the growth/propagation of a developing fire by limiting the amount of heat generated, the overall fire growth rate, the level of smoke production & flame spread in line with parameters defined within Euroclass Standards that are fully accepted within UK Building Regulations.
The key objective of a Euroclass specification is to retard fire growth to give people time to evacuate a burning building.
Note: Euroclasses are not a time rated fire performance.
Fire Resistance is a time related concept (30 or 60 mins typically) & commonly refers to the ability of a material or item to resist the passage of fire e.g. a 30 minute fire door will resist burn through for a minimum period of 30 mins the ability of timber to remain structurally load bearing after a defined amount of burning time.
6. Does Lonza Wood Protection still process timber/plywood to Class 1 or Class 0 for material to be used in permanent construction?
In short, no.
Through the Construction Products Directive it is now mandatory to fire treat timber and plywood to be used in permanent construction to Euroclasses ONLY where a harmonised Product Standard exists.