Subsidence monitoring can take many different forms; from simple measurements with a crack gauge to continuous recordings with a wireless crack movement recorder, with built in data logger. Each system comes with its own strengths and weaknesses, which must be considered in order to apply the most appropriate and effective technique.
Crack monitors or ‘tell-tales’ are the most common form of subsidence monitoring used in Ireland. They are easily sourced online so anybody with a VISA card and a drill can install them. And that sometimes is the problem.
The cheaper alternatives do not possess pre-set pegs which allow for quick and easy fixing. However, the pre-set pegs do not always allow the cursor to be square to the grid so accurate recording on installation is paramount. This can occur on uneven finishes such as wet dash or where lateral movement has taken place.
To be fair, standard tell tales (without the pre-set pegs) require a bit more thought and this wasn’t applied on a property in Roscrea, Co. Tipperary where readings from crack monitors would suggest that all cracks have closed by a distance of over 25 mm!!!!!
This is just one example of how poorly installed and recorded monitors provide no data whatsoever and can be a complete waste of time and money for the consumer. Subsidence monitoring should be performed by qualified, experienced professionals for accurate results –
Substruck Ltd. is an approved installer of Avongard crack monitors.