Crack Monitor Installation INSTRUCTIONS | CRACKMON® XL 15040A

Thank you for purchasing Buildera CRACKMON® structural crack monitors, the Engineer’s Choice™. Buildera designs and manufactures the CRACKMON XL 15040A in the USA, providing years of reliable indoor and outdoor endurance. Follow this installation guide and all safety precautions to ensure a fail-proof installation. Always wear eye protection and gloves when using power tools and structural adhesives.

Required Tools and Accessories

Buildera has developed and field-tested the following installation process, and recommends specific tools and procedures to ensure consistent, reliable installations every time. Deviations may result in sub-optimal installation and cannot be guaranteed. Due to the larger size and weight of the CRACKMON XL series crack monitors, mount with epoxy and heavy-duty corrosion-resistant fasteners for best results. Use professional discretion for any and all substitutions.

RECOMMENDED TOOLS (Minimum Requirements)

  • 1/2" Percussion hammer drill (Milwaukee® cordless M12/M18 series or similar)
  • 1/4" Hex impact driver (Milwaukee M12 Fuel Model 2453-20 or similar)
  • 1/4"-diameter round or tri-shank concrete hammer-drill bit (Bosch or similar)
  • 3-mm hex impact-driver bit with 1/4" hex shank
  • Black marker (Sharpie® or similar)
  • 12"-24" carpenter level (Stabila® or similar)
  • Stiff wire or nylon brush
  • Metric tape measure or ruler
  • 1/4" cylindrical wire brush (for cleaning dust from bored holes)
  • Compressed air (spray can with plastic straw nozzle)
  • Hammer (12 - 20 oz)
  • 5/16"-impact socket driver with 1/4" hex shaft
    (DEWALT DWA2222IR 5/16" Impact-Ready Cleanable Nutsetter, Milwaukee SHOCKWAVE® 49-66-0503, or similar)
  • (1) Dual syringe Buildera STRUPOXY® structural epoxy (1 oz)
  • Mixing cup for epoxy (may also use scrap piece of wood or heavy cardboard)
  • Rag for cleanup

ACCESSORIES (Mounting Hardware)

  • (4) concrete anchors (Toggler® Alligator A6F supplied with each CRACKMON)
  • (4) #10 x 1-1/2" stainless-steel sheet-metal fasteners with EPDM washers


Prior to shipment, Buildera pre-configures the CRACKMON 15040A at the 0/0 (X-Y) origin (Figure 1 below). This provides a relative X-axis displacement range of -55 to +155 mm (including 5-mm over-range on each end). This is the optimum starting position for larger existing cracks, fissures, or expansion joints where negative crack motion is possible. Two M5-0.8x10 mm metric nylon fasteners (one on each side of the measurement grid) secure the top and bottom plates during installation, ensuring perfect X-Y origin alignment. Always remove the nylon screws after mounting, and retain them for future CRACKMON re-use.

If the crack, fissure, or expansion joint is already at or near its minimum possible displacement (closed condition), use mounting Position 2, starting at -50 mm on the X-axis (Figure 2 below). This position allows up to -5 mm of crack closing, and +155 mm of positive crack opening. When using Position 2, remove the two M5 (5 mm) nylon screws securing the two plates together, and reposition the clear top plate until the red crosshair aligns at the -50 mm mark on the X-axis  measurement grid. The nylon screws help to protect the clear top plate from scratches and inadvertent cracking of the measurement device. Over-torquing fasteners may crack the gauge, voiding the warranty.

 FIGURE 1. CRACKMON XL 15040A Crack Monitor [Standard Mounting Position] | Range: -55 mm to +105 mm from 0/0 X-Y origin

FIGURE 1. CRACKMON XL 15040A Crack Monitor [Standard Mounting Position] | Range: -55 mm to +105 mm from 0/0 X-Y origin

 FIGURE 2. CRACKMON XL 15040A Crack Monitor [Offset Mounting Position] | Range: -5 mm to +155 mm from -50/0 X-Y origin

FIGURE 2. CRACKMON XL 15040A Crack Monitor [Offset Mounting Position] | Range: -5 mm to +155 mm from -50/0 X-Y origin

Fastening Methods

The CRACKMON XL 15040A features a redundant fastening method including horizontal and vertical slotted holes for fasteners, as well as Buildera's exclusive TAMPERLOK™ Epoxy-Grip Technology for tenacious adhesion between the measuring device and the substrate. Due to the larger size and heavier weight of the CRACKMON XL 15040A, and to improve tamper resistance, Buildera strongly recommends a dual mounting method that combines both mechanical fasteners and epoxy adhesive.


  1. Identify and tag the cracks, fissures, or expansion joints to measure.
  2. Use a stiff nylon bristle brush to clean and remove loose debris from crack and mounting area. Keep surface dry.
  3. Select and configure the CRACKMON for mounting position 1 (standard), or position 2 (offset) as illustrated above in Figure 1 and Figure 2, respectively. For position 2, remember to reposition the top plate and re-secure with the nylon screws.
  4. Position and level the CRACKMON crosshair generally over the center of the crack. For vertical and 45-degree shear cracks, position the X-axis parallel to the ground. If the crack is more horizontal in nature (less than 45 degrees from horizontal), rotate the CRACKMON 90 degrees such that the X-axis is now perpendicular to the ground.
  5. Locate the four 22 mm x 6 mm horizontal and vertical slots on each end of the CRACKMON. Mark two hole locations on the wall or substrate on each side for fasteners. The center-to-center spacing between holes is 40 mm. Temporarily set aside CRACKMON is a safe location.
  6. Bore four 1-1/2” (4 cm) deep holes using a cordless hammer drill and 1/4” (ø6 mm) concrete bit. The center-to-center hole spacing is 40 mm on each mounting flange. Drill accurately to ensure proper alignment with the fastener holes and the wall. Wear eye protection!
  7. Before inserting the anchor, thoroughly clean the hole using the 2x2x2 method. This method is as follows:
    (A) After drilling the concrete or masonry to the correct depth, blow out debris from hole using compressed air. A compressed-air can is convenient. Insert the compressed air straw tube to the bottom of the hole. Do not just blow from the top, as this will trap the dust inside. Repeat this step a second time.
    (B) Insert a 1/4" nylon spiral brush into the hole to agitate the sidewalls, removing loose debris and dust. Repeat this step a second time.
    (C) Finally, blow out the remaining dust and debris using compressed air, making sure that the air starts at the bottom of the hole. Repeat this step a second (final) time. The hole should now be free of excess dust and debris.
  8. Measure the hole depth and confirm that each hole is at least 1-1/2" deep and that the hole is generally free of dust and debris.
  9. Follow directions to mix sufficient epoxy adhesive. Discard first few pumps until equal portions of Part A and Part B can be mixed. Failure to mix equal parts may result in cure failure. Use only Buildera-approved thixotropic (thick, non-sagging) epoxy (STRUPOXY or similar) with a 5-minute set-up.
  10. Locate the four 1/4” (ø6 mm) A6 Toggler® Alligator® plastic anchors. Roll the first anchor in the epoxy, thoroughly coating the outer surface. 
  11. Insert one anchor into each hole. Tap flush with a hammer until flange is flush with substrate. For best results, do not use any other anchor unless pre-approved by Buildera.
  12. If using machine-screw type screws to secure the CRACKMON to the wall, you may pre-thread the anchors using an M5-0.8 hand tap, being careful not to strip the anchor. However, if using the supplied coarse-thread sheet-metal screws, no pre-tapping is necessary.
  13. Using the mixing stick that accompanies the epoxy, apply an ample coating of epoxy (1 - 2 mm) on the backside of the CRACKMON mounting fins in the area of the nine epoxy-grip holes, covering at least a 25 x 25 mm area (1" x 1"). Back-butter the CRACKMON to force the epoxy into the small grip holes. A rough or uneven surface may require a thicker layer of epoxy.
  14. With ample epoxy on each fin, position and fasten the CRACKMON® with supplied #10 x 1-1/2” stainless-steel sheet-metal screws and ribbed compression washers. The ribs face outward. Over-torquing screws may inadvertently damage the gauge, shear off the screw head, or crack the measuring device.
  15. Use a cordless impact driver or a screw gun with the clutch set at the lowest speed and setting. Carefully tighten the fasteners until flush and firmly pressed against the CRACKMON. Tighten last turns by hand to avoid over-torquing. The CRACKMON should now be firmly anchored on the wall.
  16. Allow the epoxy to cure for 30 minutes and then remove the (2) nylon positioning screws to allow free motion of the two plates. Failure to remove the nylon screws may result in breakage due to compression or tension of the device due to differential movement over time.
  17. Note the X-Y starting position on TRACARD® or progress sheet. Generally this will either be 0-0 (standard position) or -50,0 (offset position).
  18. Inspect movement periodically. Document with phone/camera and Buildera CRACKMON® 224R Crack-Width Comparator (ACI compliant).
  19. Tamper-resistant fasteners may be used for improved vandal resistance. Consult Buildera for additional options.


Upon project completion, the CRACKMON may be either left in place indefinitely, or removed. The following procedure will minimize surface damage to the structure:

  1. Remove the four 1-1/2" screws in the slotted holes holding the CRACKMON to the wall
  2. If no epoxy was used during the original installation, the CRACKMON should be free for re-use
  3. If the CRACKMON is still secured via the epoxy, use an oscillating tool with a fine-kerf blade to remove the CRACKMON. Some epoxy residue may exist on the surface. Light sanding may help to remove large amounts. Clean remaining dry epoxy with mineral spirits or alcohol. If the surface was painted, minor touch-up will be required.