Crack Monitors & Tell Tales
Crack monitors and telltales are used to record visible changes in cracks over time. Installed across a crack or used as a reference during repeat inspections, they provide a consistent way to compare movement or crack width at the same location.
At Celtic Surveys, our Distance Monitoring & Measurement range includes crack monitoring equipment for building inspections, maintenance checks and condition surveys. The right product will depend on the surface, crack position and whether you need to record width, movement or changes across a corner or flat surface.
Using a Crack Monitor for Repeat Measurements
A crack monitor is typically installed across a crack so that its position can be checked again during later inspections. The initial reading provides a baseline, and later readings can then be compared with it.
Depending on the design, a crack monitor may show relative movement through changes in a marked scale or reference position. Recording the installation date, location, orientation and first reading makes it easier to compare results consistently over time.
For repeat monitoring, the unit should remain securely fixed and undisturbed. Any damage, loosening or movement of the monitor itself should be recorded because this can affect later comparisons.
A crack monitor records what is happening at the measured point. It does not by itself determine why the crack formed or what the structural significance may be.
Crack Monitors, Tell Tales and Crack Width Gauges
Different tools are available depending on what needs to be measured.
A telltale crack monitor is normally fixed across a crack to provide a reference for later observations. Straight designs are suitable for compatible flat surfaces, while corner versions are available for cracks that cross internal or external angles.
A crack width gauge or crack scale is used differently. Rather than being left in place, it can be positioned over a visible crack so the width can be compared with marked graduations.
Where close measurement of visible crack width is the main requirement, our Crack Width Measurement range provides additional equipment for this type of inspection.
Other products may include fixed reference discs, crack monitoring gauges and pocket microscopes. Each method measures something slightly different, so the product should be chosen around the inspection objective rather than assuming one tool can cover every type of crack measurement.
Monitoring Cracks on Walls and Corners
Surface type and crack position are important when choosing monitoring equipment.
A standard flat crack monitor is intended for installation across a suitable flat surface. If the crack crosses a corner, a monitor specifically designed for internal or external angles may be required.
The fixing method also matters. Adhesive or other mounting materials should be suitable for both the monitor and the surface being inspected. Surface condition, access and the likelihood of accidental disturbance should also be considered before installation.
Once installed, readings should be taken consistently from the same reference position. Photographs can also help document the condition of the crack and monitor it during repeat visits.
Choosing the Right Crack Monitoring Equipment
Start by deciding what you need to record.
If the purpose is to compare movement over time, an installed crack monitor or telltale may be appropriate. If the main requirement is to measure the visible width of a crack during an inspection, a crack gauge, scale, or microscope may be more suitable.
Consider:
- Whether the crack is on a flat surface or corner
- The expected direction of movement
- The required measurement range
- The scale or resolution provided
- The fixing method
- Surface and working conditions
- How readings will be recorded during later visits
Product specifications vary, so check the individual measurement range, scale and installation requirements before selecting equipment.
Recording Crack Movement Over Time
Consistent record keeping is important when using crack monitors.
For each monitored point, record the location, installation date, initial reading and orientation. Later inspections should use the same reference points and include the date and observed reading.
A single reading only records the condition at that time. A series of readings provides the information needed to compare changes between inspection dates.
If a monitor becomes damaged, loose or disturbed, this should be recorded before using the reading for comparison.
Crack Monitors & Tell Tales from Celtic Surveys
Celtic Surveys supplies crack monitors, tell tales, crack gauges and related equipment for repeat crack observation and measurement.
Choose the product that matches the surface, crack position and measurement method required for your work. If you need help selecting suitable crack monitoring equipment, call 01 801 1335 or email sales@celticsurveys.ie for product advice before ordering.