Visual Strength Grading of Timber
Visual strength grading is a method of determining the strength of a piece of timber intended for structural use. The study of the features present in a selected piece of timber will determine the grade awarded for its use as a structural component.
Visual strength grading of temperate hardwoods (to BS5756)
Designers and engineers need to know that the structural timbers that they specify will perform as envisaged under working loads and stresses.
The performance of a structural timber component is determined by its species, the consequence of its natural growth characteristics and its dimensions.
It is these growth characteristics that include, knot area ratio, slope of grain, fissures, insect and fungal defects that are assessed by visual strength graders and will determine the strength classification assigned to each piece of timber.
We grade timbers that are destined for new buildings and extensions, or for the repair of historic buildings.
Changes in how an old or historic building is used can subject structural timbers to new loadings and stresses. We can undertake in-situ, visual strength grading assessments of these timbers to determine their suitability or to help identify that strengthening works may be necessary.
Additionally, these assessments can be undertaken at height using rope access.
Visual Strength Grading of softwood to BS4978 accreditation expected within 2007.
The above image shows a parcel of timbers that we strength graded that were to be used in the roof structure of a new build house.