Carcassing
Whatever your requirement, we can deliver - from simple unfinished sections of carcassing timber from our vast stock holding, to our full and extensive range of market ready and bespoke wood products.
All our stock is sourced from the very best mills throughout the Uk and Europe where our long standing partnership and strict quality control mechanisms ensure 100% quality every time. From Russian or Scandinavian Redwood/Whitewood to seasoned or graded Baltic carcassing, whatever the wood C16,C24, we will supply it quickly, efficiently and at a price that's always competitive.
When Size Does Matter
In the past the traditional method of regularising timber joists in width was a common practice. However , with the introduction of engineered I Beams into the Uk market and the variations in localised machine performance Along with the problems poor regularisiation could cause.Over the last few years both Countries and companies have been forced to look at providing joists that were accurately machined to size and that had a more aeshthetic appearance.The result is that in today's market carcassing is now more commonly S4S (sawn 4 sides ) or planed all round.The result of doing this additional machining does make the product appearance look better and ensures that the problems caused with width variations are minimised.
However , one off-shoot of this is additional process, is also that the timber joist thickness has also been decreased.This means that where traditionally Joist sizes were 50mm and 47mm thick , most joists are now supplied machined to a finish thickness of 47mm or 44mm .Please check with your local Howarth Timber and Building Supplies for details of speciifcations available.
The structural performance of a timber member is calculated using its strength grade
and its exact dimensions. Any form of processing which removes wood from the crosssection
will reduce the load that a piece can carry, or will reduce the span over which the
same load can be carried.
BS EN 336:2003 - Structural Timber. Sizes, Permitted Deviations - is the key Standard
referenced by grading standards such as BS 4978 - visual strength grading - and
BS EN 519 - machine strength grading - and defines very strict dimensional tolerances
within which structural timber must be produced. These tolerances recognize the small
differences in dimension which may occur within a piece or parcel due to inconsistent
sawing or machining.
At 20% MC Dimensions < / = 100 mm Dimensions > 100mm
Class T1 Tolerance (-1 +3) mm (-2 +4) mm
Class T2 Tolerance (-1 +1) mm (-1.5 +1.5) mm
However, the tolerance classes do not permit consistently under-sized timber, with the
Standard clearly stating:
"The average actual thickness and the average actual width of square-edged timber
shall not be less than the target sizes."
Of the two tolerance classes, T1 applies to sawn dimensions and T2, the more
stringent requirement, applies where some form of processing has taken place.
It is important that you ensure that you and/or your architect / structural engineer or builder have worked out the timber sections to be specified to allow for this size reduction. Failure to allow for this loss in thickness could/ will cause major performance and structural issues .
We have attached a copy of the 44mm span tables for your information but suggest that it is the responsibility of the structural engineer, architect and builder to ensure correct sized materials are specified and supplied. Additionally we have also attached details of span table information that can be obtained directly from TRADA TECHNOLOGY on 01494-569602.
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