BUILDERA CRACKMON 4020A Heavy-Duty Concrete Crack Gauge (3-Pack)

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The BUILDERA CRACKMON® 4020A Heavy-Duty Concrete Crack Gauge is a vibrant, new generation of flexible crack monitors for demanding commercial and industrial use. Engineered and built from the ground up in the USA. Epoxy not included.


  • Extreme durability—50% thicker proprietary polymer compared to classic model (4.5 mm vs 3 mm)
  • New 2D+ polar magnitude and X-Y displacement measurement grid with precision TickPoints™ improve measurement accuracy
  • Vibrant rich-black and red printing on opaque white background doubles the contrast and legibility
  • Unique serial IDs yield unprecedented engineering traceability in a crack monitor
  • Integrated GeoQR™ technology for online instructions and geolocation tagging
  • Flexible mounting arrangement optimized for #8(M4) or #6(M3.5) tamper-resistant fasteners and epoxy
In addition to familiar X-Y 2D Cartesian measurements, the redesigned measurement grid now includes a new polar-magnitude measurement function, effectively computing the angular hypotenuse (magnitude) of change from the zero-crossing.  To improve reading accuracy over the entire range, the measurement grid now sports variable-length tick marks, as well as patent-pending TickPoints™ at 1 mm x 1 mm intervals. TickPoints™ improve measurement accuracy as the measurement cross-hairs traverse the grid. This is particularly helpful when the two plates are no longer parallel.

The BUILDERA CRACKMON® 4020A is printed in five process colors, including a high-contrast rich-black text UV-cured over a thick double layer of brilliant opaque white ink. The result is a bright, bold measurement grid with a 2X contrast improvement that's much easier to read over a wide range of lighting conditions. 

Each crack monitor features a unique 15-character serial number that tracks the country of origin, design revision, and unique ID. This ensures engineering traceability in the field and offers a significant benefit and professionalism in forensic analysis. An imprinted QR code works with your mobile phone to access installation instructions and other helpful data, wherever you may be.

The impact-absorbing drilling guide features an aggressive adhesive that sticks to concrete, masonry, stucco, steel, wood, and other rough surfaces. Simply peel it, stick it, and drill it. Improved mounting options now include both horizontal and vertical slots, optimally sized to accept four different screw types including English (#8/#6) and Metric (M4/M3.5) fasteners, respectively.


30 mm x 152 mm x 9 mm (1.20" x 6.00" x 0.35")
40 mm x 20 mm (scale divided as ±20 mm x ±10 mm)
±0.5 mm, typ.
Mounting Holes
(4) Per side
Proprietary polymer
Tensile Strength
11,000 psi (ASTM D-638)
Flexural Strength
117 MPa (17,000 psi), ASTM D-790
Tensile Impact Strength
20 ft-lb/in^2
Rockwell Hardness
M-95  (ASTM D-758)
Hole Dimensions
#8/M4 Fasteners: .60" x .20"
#6/M3.5 Fasterns: .20 x .16"
Recommended Fasteners
#8 Torx®-Plus Pan Head Security Sheet-metal Screw, Stainless Steel (18-8 alloy) and washers
(Note the use of washers during mounting it essential to securing the crack monitor and to distribute load across the mounting surface area. Tighten by hand. Do not over-torque)
Specific Gravity / Relative Density
Light Transmission-Total
Water Absorption
0.4% by weight (ASTM D-570)
Thermal Expansion (ASTM D696, -30C to +30C)
54 µm/(m-°C), 30 µin/(in-°F )
Maximum Recommended Continuous Service Temperature
< 85°C (185°F)
Deflection Temperature @ 264 psi (1.8 MPa)
95°C (203°F)
Melting Temperature
150°C (300°F)
Self Ignition Temperature
445°C (833°F)
Flame Spread Index
115 (ASTM E-84)
Smoke Density Rating
3.4% (ASTM D-2843)