Products : Surface Prep : Waterproofing Membranes & Underlayments : Crack Buster® Pro Crack Prevention Mat Underlayment

Crack Buster® Pro Crack Prevention Mat Underlayment

A self-bonding, fabric-reinforced asphaltic mat that reduces crack transmission in tile and stone floors. For both full and partial floor applications, Crack Buster® Pro is an anti-fracture membrane for horizontal cracks up to 3/8" (9.5 mm). Its strong self-adhesive backing and uniquely designed surface provide secure bonding for all types of ceramic tile, natural stone and terrazzo.

  • Features & Benefits
  • Technical Documents
  • Warranty Information

Key Features

  • Rated for extra heavy duty applications
  • Easy application - Peel & stick
  • Elastomeric - Reduces crack transmission in tile and stone floors
  • Reduces downtime allowing immediate installation of tile
  • Seal surface with Custom's Peel & Stick Primer

Suitable Substrates

  • Concrete, cement mortar, masonry
  • Cement Backerboard
  • Exterior Plywood and OSB (interior, dry areas only)
  • Exterior Decks – Contact Technical Services
  • Post-Tension Concrete – Contact Technical Services
  • Lightweight Concrete (min. 2000 psi compressive strength)
  • Gypsum-Based cement topping (min. 2000 psi compressive strength)
  • Existing ceramic tile and resilient flooring

Composition & Materials

Crack Buster® Pro is an elastomeric, fabric-reinforced mat underlayment, with modified asphalt and a polyurethane adhesive.


  • Extra heavy-duty rating for installation within diverse substrates.
  • Exceeds ANSI A118.12 standards for crack isolation material.
  • Eliminates crack transmission in tile and stone floors.
  • Easy and quick self-adhesive installation reduces downtime for tile and stone installation.


  • Do not bond directly to hardwood, Luan plywood, particle board, parquet, cushion or sponge-back vinyl flooring, metal, fiberglass, plastic or OSB panels.
  • Do not use as a wear surface.
  • When setting glass tile larger than 6" × 6" (15 × 15 cm), contact Custom's Technical Services for recommendations.
  • When setting dimensional stone larger than 12" × 12" (30 × 30 cm), contact Custom's Technical Services for recommendations regarding subfloor deflection requirements.


36" x 75' (.91 x 23 M) Rolls

Technical Data

Applicable Standards

American National Standards Institute (ANSI) ANSI A108.01, A108.17 and A118.12 American National Standards for the Installation of Ceramic Tile ASTM International (ASTM)

  • ASTM C627 Standard Test Method for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson-Type Floor Tester
  • ASTM D638 Standard Test Method for Tensile Properties of Plastics

Tile Council of North America (TCNA) TCNA Handbook for Ceramic Tile Installation, TCNA Method EJ171, F125 & F125A


Technical Data Sheet Technical Data Sheet - French Technical Data Sheet - Spanish Material Safety Data Sheet - English Material Safety Data Sheet - Sound Guard

Product Warranty

Custom® Building Products warrants to the original consumer purchaser that its product shall be free from defects in material and workmanship under normal and proper usage for a period of one year following the date of original purchase. CUSTOM's sole liability under this warranty shall be limited to the replacement of the product. Some states, countries or territories do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty will not extend to any product which has been modified in any way or which has not been used in accordance with CUSTOM's printed instructions. CUSTOM makes no other warranties either expressed or implied. This warranty gives you specific legal rights, and you may have other rights that vary from state to state or from one country/territory to another.  This warranty is not transferrable.

Warranty Duration

When Crack Buster® Pro Crack Prevention Mat Underlayment is used as a part of a qualifying full installation system of CUSTOM products, the installation can qualify for up to a lifetime system warranty. CUSTOM will repair and/or replace, at its discretion, the affected area of the system. For more information, find details and limitations to this warranty at

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