Timber Condition Assessments (TCA)
When a client needs to know the condition of structural timbers or requires an assessment of insect and fungal decay, Exposure Surveying Ltd offer complete and cost effective solutions.
We can investigate insect and fungal timber decay in domestic and commercial properties, timber structures and playground equipment found in public spaces.
Timber Condition Assessment, Hampton Court Rail Station
Client: Frankham Consultancy Group
Non-destructive Assessments
We use a range of non-destructive testing techniques, including Ultrasonic Decay Detection(UDD) instrumentation which quickly locates cross sectional decay beneath the surface of timbers. The Resistograph microdrill is used to help quantify the extent of sub-surface decay and is extremely adept at assessing timbers imbedded in masonry walls.
Ultrasonic Decay Detection (U.D.D)
We use the U.D.D to detect decay beneath the surface of timber. An ultrasound pulse is transmitted through the subject timber and the time it takes to cross the section is recorded. The signal travels faster through ‘good’ timber and therefore, delays outside the allowed parameters, provide a strong indication of the presence of cross sectional decay.
The instrumentation is very sensitive and can even detect the early onset of decay.
Large numbers of timbers can be quickly and cost effectively assessed using this non-destructive technique.
Resistograph Investigations
We use the Resistograph microdrill for the assessment and detection of sub-surface decay and defects in timber. It is extremely adept at assessing decay in the ends of beams and joists embedded in masonry.
A 1.5 mm needle is drilled at a constant speed into the subject timber and the microdrill measures the resistance of the timber against the needle, producing a 1:1 scale reading.
The reading is analysed and the exact location of any decay present will be identified and is quantifiable.
Holes are refilled automatically with the extraction of the needle, leaving nothing visible or at worst something resembling a beetle flight hole, depending on the timber species being assessed.
The Resistograph and U.D.D are the most accurate, sensitive and cost effective way of assessing sub-surface decay in timbers.
Borescope
We use borescopes to look behind panelling, below suspended timber floors and into ceiling voids, allowing a thorough assessment with the minimal of disruption and loss of fabric.
In-situ Visual strength grading (BS5756)
This is the in-situ assessment of structural timbers in order to ascertain their potential load bearing capacity. The timber is assigned a grade based on species, slope of grain, knot area ratio, fungal and insect activity etc.
Structural engineers, architects and designers can use this information to make informed decisions when considering the implications of a change of use or repair to an existing building.
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.
Impartial reports
A report of the investigation will include the appropriate written, graphical and photographical studies as well as extensive data collected from monitoring instrumentation. This gives the client an independent, objective and informed assessment of the structural condition of the timbers, enabling informed decisions to be made.
Dry timber is not at risk from fungal or insect decay, so it is essential to investigated how the timbers have become damp before any recommendations can be made.
The recommendations section of the report will focus on the repairs and modifications that are necessary for the defects to be resolved.
You can commission timber condition assessments on the most remote parts of buildings and structures by utilising the services of our rope access team. It will be our IRATA trained (Industrial Rope Access Trade Association), timber specialist, who will undertake the assessment at height.
