Products : Surface Prep : Waterproofing Membranes & Underlayments : Custom® 9240 Waterproofing and Anti-Fracture Membrane

Custom® 9240 Waterproofing and Anti-Fracture Membrane

A flexible, seamless waterproofing membrane system with a liquid-applied polymer and reinforcing fabric that bonds to a variety of substrates and is ideal for heavy duty service installations. Designed for waterproofing tile and stone installations, Custom® 9240 also provides protection from fractures to 1/8" (3 mm) over shrinkage and other non-structural cracks.

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Key Features

  • Waterproofing membrane rated for extra heavy-duty service
  • Anti-fracture protection up to 1/8" (3 mm)
  • Listed with IAPMO for use as a shower pan liner


  • Rated for extra heavy duty service
  • Forms flexible, seamless waterproofing for varying substrates
  • Provides anti-fracture protection to 1/8" (3 mm) for shrinkage and non-structural cracks
  • Meets Uniform Plumbing Code specifications for use as a shower pan liner


Applicable Standards

American National Standards Institute (ANSI) ANSI A108.01, A108.13, A108.17, A118.10 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


Custom® 9240 has tested and complies with Uniform Plumbing Code and International Plumbing Code standards for use as a shower pan liner per IAPMO Research and Testing, Inc., File No. 4244. Custom® 9240 has tested and complies with International Building Code (IBC), International Residential Code (IRC) and International Plumbing Code (IPC) standards for water resistance per ICC Evaluation Service, ESR-1413.

Conformance to Building Codes

Installation must comply with the requirements of all applicable local, state and federal code jurisdictions.

Composition of Product

Custom® 9240 is a system with a liquid-applied polymer and reinforcing fabric.

Environmental Consideration

Custom® Building Products is committed to environmental responsibility in both products produced and in manufacturing practices. Use of this product may contribute to LEED® certification.

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
  • Floor heating systems - contact Technical Services

General Surface Prep

USE CHEMICAL-RESISTANT GLOVES, such as nitrile, when handling product.

Exterior and wet areas must have proper sloping to drains. All surfaces must be structurally sound, clean, dry and free from contaminants that would prevent a good bond. Newly prepared concrete must be  troweled smooth and textured to a fine broom finish and cured for 28 days. Existing surfaces must be scarified and leveled, and all defects must be repaired. Cracks should be treated in accordance with TCNA F125 or TCNA F125A.

Movement Joint Placement

Do not bridge joints designed to experience movement. Carry these types of joints through the tile work. Clean the joint and install an open or closed cell-backer rod to the proper depth, as outlined in the Tile Council Handbook, EJ171. Next compress sealant into the joint, coating the sides and leaving the sealant flush with the surface. When the sealant is dry, place bond-breaker tape over the joint. Apply a liberal coat (15-20 mils) of Custom® 9240 liquid over the joint and the substrate, following the instructions provided previously. Install the tile work onto the membrane, but do not bridge the joint. After the tile work is properly set, follow the architect's and manufacturer's instructions to fill the joint with Commercial 100% Silicone Caulk.

Health Precautions

Wear impervious gloves and eye protection while using this product. Avoid contact with eyes or prolonged contact with skin. Wash thoroughly after handling. If eye contact occurs, rinse cautiously with water for several minutes, remove contact lenses if easy to do: continue rinsing. Immediately seek medical advice if symptoms are significant or persist. Do not take internally. KEEP OUT OF REACH OF CHILDREN.

Limitations to the Product

  • Do not apply to surfaces that may drop below 40°F (4°C) within 72 hours of application.
  • Do not apply over wet surfaces or surfaces subject to hydrostatic pressure.
  • Do not use to bridge or cover over existing expansion, control, construction or cold joints.
  • Do not use as an adhesive.
  • Do not use as a wear surface; the membrane must be covered with tile or other permanent flooring.
  • Do not use solvents in conjunction with the membrane.

Bonding to Backerboards

Custom® 9240 reinforcing fabric and the third coat of liquid may be omitted from main applications over interior walls and other vertical surfaces made with cementitious backer units (CBU) or gypsum wallboard. Coves, corners, seams and board joints, however, must be pretreated as described previously.

Application of Product

Custom® 9240 for 2-Part System for heavy duty and commercial applications

Mortar Bed over Framed Structures – B414
Cement Backerboard Walls – B415
Surface Bonded Waterproofing – B421

Download the illustrated installation details by clicking on the link above or go to, select “Tile” as the installation type and select the appropriate illustrated TCNA detail by number (example: B414).

Apply a liberal coat of liquid, approximately 8" (20 cm) wide, over cracks and joints. Embed the 6" (15 cm) wide reinforcing fabric into the first coat of liquid. Apply a second liberal coat of liquid to seal the fabric. To pretreat coves and corners, apply a liberal coat of liquid. Fold 6" (15 cm) wide fabric in half and embed it into the liquid, flashing the fabric 3" (7.5 cm) up walls. Apply a second liberal coat of liquid to seal the fabric. Wet-coat thickness should be 15-20 mils thick. Do not install over structural cracks, cracks with vertical movement or cracks with more than 1/8" (3 mm) horizontal movement.

To pretreat penetrations, pack any gaps around pipes, lights or other penetrations with a compressible backer rod and suitable waterproof sealant. Apply a liberal coat of liquid around the penetration opening and embed pieces of 6" (15 cm) wide fabric into the liquid. Cover with a second layer of liquid. After curing, seal the flashing with a waterproof sealant. For expansion joints and cracks in excess of 1/8" (3 mm), treat as expansion joints and follow the instructions provided previously for expansion joints.

To pretreat drains for a 2-part system, have a clamping ring with open-weep holes for thin-set application. The drain should be fully supported, without movement, and should be even with the substrate plane. Cut a square of reinforcing fabric approximately 38" x 38" (96 x 96 cm). In the center of the fabric, cut a hole that matches the diameter of the drain throat. Apply a liberal coat of liquid to the bottom flange. Center the circular cutout over the drain throat and embed the fabric into the liquid, making sure it does not obstruct the drainage hole. Apply an additional coat of liquid 15-20 mils thick. After curing, apply a waterproof sealant bead where the fabric cutout meets the drain throat. Clamp the upper flange onto the membrane and tighten. Caulk with 100% Commercial Silicone Caulk around the flange where the membrane and upper flange make contact. A toilet flange may be handled in much the same manner.

Before beginning the 2-part Custom® 9240 application, allow all pretreated areas to dry to the touch. Using a brush or roller, apply a liberal coat (15-20 mils thick) of liquid over the substrate, including pretreated areas. Lay reinforcing fabric into the wet liquid and smooth out any wrinkles. Press the fabric with a brush or roller until liquid bleeds through to the surface. Lap seams approximately 2" (5 cm). Flash the membrane over pretreated coves and corners so that the areas will have two layers of fabric. Apply another liberal coat of liquid over the fabric to saturate it. Let the top coat dry to the touch, approximately 1-3 hours. Apply another liberal coat (15-20 mils thick) of liquid over the entire surface to the seal membrane. When the last coat has dried to the touch, inspect final surface for pinholes, voids, thin spots or other defects and use additional liquid to seal defects. Reinforcing fabric and the third coat of liquid can be omitted over interior, vertical cement backerboard or drywall surfaces; pretreatment is, however, still required.

Custom® 9240 for 1-Part System for Residential and Light Commercial Applications

Using the above instructions: reinforcing fabric and third coat of liquid can be omitted; however, pretreatment is required for coves, corners, seams, expansion joints and drains.

Curing of Product

Custom® 9240 is dry when it turns a solid dark orange, normally 1.5-2 hours; ambient conditions can, however, increase drying time to 12 hours. Installation can be flood tested 24 hours later. Swimming pools should not be filled for 7 days.

Tile and Stone Installation

Install tile or stone with a Custom® Building Products polymer-modified mortar that meets ANSI A118.4, A118.15 or A118.11 standards.

Cleaning of equipment

Clean tools and hands with water before the material dries. Clean all spray equipment immediately after use.


Do not freeze.

Product Maintenance

Properly installed product requires no special maintenance. Do not use as a wear surface.

Ordering Information


  • 6 gallon (22.7 L) pail of liquid
  • 6" x 75' (0.15 x 22.85 M) fabric roll
  • 36" x 100' (0.91 x 30.5 M) fabric roll
  • Kit containing 6 gallon (22.7 L) pail of liquid, one 6" x 75' (0.15 x 22.85 M) fabric roll and one 36" x 100' (0.91 x 30.5 M) fabric roll

Warranty Information

Product Warranty

Obtain the applicable LIMITED PRODUCT WARRANTY at or send a written request to Custom Building Products, Inc., Five Concourse Parkway, Atlanta, GA 30328, USA. Manufactured under the authority of Custom Building Products, Inc. © 2017 Quikrete International, Inc.

Warranty Duration

When Custom® 9240 Waterproofing and Anti-Fracture Membrane 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

Coverage Chart

Coverage is for a full Custom 9240 kit, containing a 6 gallon (22.7 L) pail of Part 1 Liquid, one 6" x 75' (15 cm x 22.85 m) roll of fabric and one 36" x 100' (91.5 cm x 30.5 m) roll of fabric.

Size Max Coverage
1 Kit 300 ft² (27.87 m²)

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