Through our Professional & Technical Services Roster, Benfield ATT are able to offer the above specialist surveys...
Structural Timber Surveys
Our experienced timber surveyors use specialist techniques such as decay detection drilling to determine the condition of structural timbers. All our specialist timber condition investigations include a moisture content survey to establish if any decay is on-going or historic. Benfield ATTsβ reports highlight areas of structurally significant fungal decay or insect damage, and provide recommendations for repairs. The reports can be used for QS purposes and as a reference document for repair contractors.
Minimally invasive surveys β We use fibre-optic borescope examinations to search for any decay, such as dry-rot behind timber panelling, lath and plaster finishes, or dry lining. This conservation-minded service allows inspection of otherwise inaccessible cavities or voids while avoiding opening-up works and minimising any damage to decorative finishes.
Benfield ATT can provide specialist timber condition surveys of roof timbers, floor timbers, stud walls, lintels, and any other timber in buildings, for architects, structural engineers, general surveyors, and developers. Typical projects include agricultural buildings, churches, commercial refurbishments and renovations, timber bridges, and residential developments. Recommendations include fail-safe repair details to avoid fungal decay in the future. Our experts have experience liasing with conservation bodies and building control on behalf of clients. Our services can be tailored to suit your budget.
In-Situ Timber Strength Assessment
Avoid unnecessary strengthening works to existing timbers β In our experience structural engineers sometimes assume, for calculation purposes, a strength class for existing timbers (for instance C16) that undervalues the load-bearing capacity of the wood. Additionally, in large section timbers, drying fissures which may have very little influence on load-bearing capacity may be mistaken for fissures caused by over-stressing. Both the above can easily result in costly strengthening works that may be avoidable if in-situ visual strength grading is carried out.
Justification of existing structures for calculation purposes β In-situ visual strength grading allows the structural engineer to assign strength values to existing timbers with increased accuracy, thereby minimising assumptions and any associated risk.
Qualified visual strength graders assess timbers against the requirements of the relevant British and European Standards (BS 4978: 1996 for softwoods, and BS 5756: 1997 for hardwoods).
Species identification is critical for strength class allocation so all our visual strength grading services include microscopic examination of small samples removed from the timber, for identification purposes. The visual strength grade assigned by our graders is then matched with the species, to determine the applicable strength class (for example C16, C18 or C24 for softwoods or D30, D40 or D50 for hardwoods) as given in BS 5268-2: 2002.
In-situ visual strength grading requires access to three faces of each piece, along the full length. Timbers must be free of heavy coatings or dirt, to allow the size and location of knots and fissures, and grain direction to be assessed.
Species Identification
For listed buildings or other buildings of historic interest β ensure that any replacement or additional timbers can be matched to the existing, for conservation or aesthetic purposes.
An essential element of in-situ strength grading assessments* β strength grading against the requirements of BS 4978 (for softwoods) or BS 5756 (for hardwoods) requires identification of the timber species, so that the correct strength class can be assigned for structural calculation purposes
Species clarification/dispute settlement β species that appear very similar may have very different properties, in terms of strength, movement, resistance to fungal decay or insect attack, and suitability for use in different service conditions. It is therefore important that the right species is used for the right application, or premature failure could occur. If you suspect that the timber supplied does not match the species you ordered, this can be clarified by microscopic species identification of a small sample.
Trained experts examine samples with a X10 hand lens to establish the gross features, and thin sections are cut from the samples for microscopic examination, to establish the anatomical characteristics. The gross features and anatomical characteristics of the samples are then matched with those of reference timber samples or with published literature.
*site inspection required.
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