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CRACKMON® Model 4020A Crack Monitors



CrackPAK™ (3)

ContractorPAK™ (18)

BulkPAK™ (50)

  CRACKMON concrete & masonry crack width monitoring kit


Free Shipping (USA)
Free Shipping (USA)
Free Shipping (USA)

CRACKMON® Quantity

(3) Qty Model 4020A (18) Qty Model 4020A (50) Qty Model 4020A
(Bulk in box of 50 pcs)


(1) Epoxy Included (3) Epoxies Included Epoxy sold separately
Five-minute hardening, premium thixotropic structural epoxy adhesive. Tensile lap shear strength: 2,270 psi. Multiple-use dual 1-ounce total reservoir syringe-type applicator. Cold-temperature resistant.


UPC 816291010006 / EAN 0816291010006 UPC 816291010013 / EAN 0816291010013 UPC 816291010198 / EAN 0816291010198

Ship Method

USPS Priority Mail with Delivery Confirmation Ground

Ships Within

1 Business Day 1 Business Day

FOB Point

Origin - California


In Stock. Each pack is based on UPC/EAN 816291010259/0816291010259 Part Number In Stock. Call (888) 888-3111 for stock on large quantities.

Product Description

The CRACKMON® is a simple, reliable, and inexpensive device that measures vertical and horizontal differential movement in concrete and masonry surfaces. Ideal for restoration or analysis of differential settlement, the CRACKMON is an indispensable tool for every contractor, builder, engineer, or homeowner. Available in three conveniently sized PAKs, each CRACKMON is precision manufactured in the USA to exacting Builders Websource® standards using premium-quality materials and workmanship for superior engineering accuracy.

Who uses CRACKMON®?

Anyone who designs, builds, manages, maintains, lives in, or inspects brick, concrete, or masonry structures. CRACKMON is used by architects, engineers, builders, home inspectors, government agencies, home owners' associations, consultants and lawyers. The fastest growing use of the CRACKMON is in pre-construction surveys which insurance companies require before tunneling or excavation can begin. By installing gauges on all noticeable cracks in buildings next to your site, you can prove whether damage does or does not occur as a result of your project.

In addition, CRACKMON is ideal for assessing ongoing damage to foundations and masonry due to earthquakes, high winds,  ground subsidence (settlement) and soil upheaval (such as high clay content).

How does the CRACKMON® work?

CRACKMON consists of two overlapping acrylic plates. One plate is white with a black millimeter grid, while the other is transparent with red crosshairs centered over the grid. Once the CRACKMON is in position across a crack, the crosshairs shift vertically or horizontally on the grid if movement occurs, making it easy to see and track crack movement.

Is the CRACKMON® accurate?

CrackMON precision crack monitor gaugeWhen installed properly, the CRACKMON is very accurate. It can measure movements as small as 0.5 mm (.020 inch) and crack widths up to 20 mm (0.79 inch). For more detailed specifications see the SPECS.

Installing the CRACKMON®

Install CRACKMON using either anchors and bolts / screws, 5-minute epoxy adhesive, or a combination of both. If anchors and screws are used, the CRACKMON can be taken down and reused, but we don't recommend this method of installation in areas easily accessible by the general public. The CRACKMON is less likely to be removed by vandals if it is firmly epoxied in place.

When deciding whether to use anchors or epoxy, take into consideration the type of surface (for example, brick, masonry, concrete), the location and the risks (including cosmetic) involved in drilling holes for anchors. In some cases epoxy putty (if you can find a supplier) is the best mounting medium as it can minimize surface damage, is more easily removed and helps compensate for uneven or curved surfaces.

The CRACKMON can even be used on corners, following these mounting guidelines:

CRACKMON® corner installation example

CRACKMON® Specifications


Heavy-duty acrylic copolymer for superior clarity. Non-yellowing.

Dimensions (overall)

152 mm x 30 mm x 9 mm

Dimensions (grid)

40 x 20 mm / 1.57 x 0.79 in


0.5 mm / 0.020 in

Max. horizontal (width) movement

20 mm / 0.79 in

Max. vertical (upward) movement

10 mm / 0.38 in

Coeff. of thermal expansion

54 um/m-degC, -30C to +30C

Country of origin

Precision manufactured in the USA to precise tolerances

CRACKMON® is a registered trademark of Builders Websource®.


  • Concrete
  • Foundations
  • Masonry
  • Walls
  • Basements
  • Slabs
  • Walkways
  • Driveways
  • Restoration
  • Earthquakes
  • Settlement

Article Tools

ASTM International