26
Timber treatment is a complex and essential aspect of specification. By knowing what you’re looking for, and appreciating what documentation should be available, you’ll ensure effective specification every time
EUROCLASS Reaction to fire test results are expressed as Euroclass classifications to EN 13501-1
to improve durability and many other characteristics. The result is a much wider choice of materials for specifiers to consider.
Documented evidence is available from all accredited timber treatment providers. Architects must ask and retain this proof to demonstrate the product will meet the anticipated service life.
Getting to grips with improved fire performance
A risk assessment or Building Regulations usually prompts the need for flame retardant treated timber. Fire (or flame) retardant treatments work by making the wood more difficult to ignite and by slowing the spread of flame, smoke and burning droplet generation, giving more time for evacuation and lessening damage to the structure. Wood and wood-based panels are generally treated to Euroclass C (limited lateral spread of flame, like a BS476 class 1 rating) or Euroclass B (very limited lateral spread of flame, like BS476 class 0). Treatment involves the impregnation of timber under controlled conditions. The smoke rating will be given as an ‘s’
value, and the burning droplets rating as a ‘d’ value.
Classification Reports exist to verify performance. They will detail timber species, thickness, substrate e.g. plasterboard, and whether the tested assembly incorporated an air gap or not. Deviation from any of these test specifics – e.g. thickness of the wood – will make the performance certificate invalid.
When specifying flame retardant timber, always check the material description in the Classification Report against the material to be used in your project. Species, size and intended use should match exactly. Only then do you have the right evidence to confirm your product’s ability to perform and to comply with the requirements of Building Control officers or insurers.
CE marking and Declaration of Performance Timber cladding and wood-based panels are subject to CE marking. CE marking compliance is the responsibility of the organisation that brings cladding and panels into the marketplace, and means the product must be accompanied by a Declaration of Performance (DoP). Usually drawn up after treatment of a wood product against fire, insist on a check to ensure your specification matches the DoP. If you need more detail, ask for the product’s Reaction to Fire Classification Report. This is issued by an independent fire test certifying organisation such as Exova.
Where to seek help Timber treatment is a complex and essential aspect of specification. By knowing what you’re looking for, and appreciating what documentation should be available, you’ll ensure effective specification every time. The WPA has a series of fact sheets to help you, in addition to a CPD accredited course. Telephone helpdesks are available at both the TDCA and WPA. When it comes to timber protection, there’s no reason to make poor specification decisions.
Janet Sycamore is the director of operations at the Timber Decking and Cladding Association
WWW.ARCHITECTSDATAFILE.CO.UK
ADF AUGUST 2019
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36
