Following a survey a small number of trees may need detailed inspection – a close examination especially for faults or errors (Collins Concise English Dictionary). This may include a climbed inspection to ensure that all areas of the tree is fully inspected, excavation of root plates, detailed measuring and record taking, identification of pests or disease, fungal infections or structural issues etc.
As part of this process internal investigation may be required to compare decayed and sound tissues. Certhia uses a Resistograph – a micro drill which records drilling resistance in the wood. It provides a read out which can be analysed to compare the wood quality within the tree.