The Complete Assembly Must Work Together

A membrane may bond securely to concrete and control moisture as intended while a primer, patch, underlayment, adhesive, coating, or floor covering above it loses adhesion.

The completed installation is a chain of bonded layers. The performance of the entire floor depends on the weakest material or interface in that chain.

Build a System Map

Before ordering materials, list every layer in the proposed assembly in the order it will be installed.

1. Concrete substrate
2. Concrete repair and crack-treatment materials
3. Moisture-mitigation membrane
4. Broadcast aggregate or bonding primer
5. Patching or self-leveling underlayment
6. Flooring adhesive or resinous coating primer
7. Floor coating, flooring, or wearing surface
8. Sealants, joint fillers, coves, and transition materials
9. Cleaning, sanitation, and maintenance products

Identify the manufacturer and exact product for every layer. Avoid generic descriptions such as “epoxy primer,” “leveler,” or “approved adhesive” when seeking compatibility confirmation.

Compatibility Has Several Meanings

Why a Membrane Surface Can Be Difficult to Bond

A cured resin membrane may be smooth, dense, nonporous, and chemically resistant. Those qualities are useful for moisture control but can make it difficult for cementitious underlayments and water-based adhesives to bond or dry properly.

The membrane manufacturer may require a primer, aggregate broadcast, sanding, abrasion, or installation of the next material within a defined recoat window.

Applying a product intended for porous concrete directly over a nonporous membrane can change its drying, open time, bond development, coverage, and working characteristics.

Primers Above the Membrane

A primer can promote adhesion, control absorbency, isolate materials, or prepare the membrane for a cementitious or resinous layer. The word “primer” does not describe one universal product.

Primer Questions

• Is the primer approved over the specific membrane?
• Must the membrane be tacky, cured, sanded, or cleaned first?
• What is the required primer coverage?
• Is dilution permitted?
• How long must the primer dry?
• What is the minimum and maximum overcoat interval?
• How should puddles and thick areas be avoided?
• Can the primer tolerate the underlayment or adhesive moisture?
• What happens if the primer becomes contaminated?
• How is an expired primer window restored?

Broadcast Aggregate

Some membrane systems require clean, dry aggregate to be broadcast into the wet membrane. After cure, the embedded aggregate provides a textured mechanical bonding surface.

The manufacturer should specify the aggregate type, size, moisture condition, application rate, and whether the broadcast is light, uniform, or to refusal.

Broadcast Problems

• Aggregate applied after the membrane becomes too tack-free to accept it
• Insufficient aggregate leaving glossy resin areas
• Excess aggregate forming piles or uneven texture
• Damp or contaminated aggregate
• Wrong aggregate size or mineral type
• Loose aggregate not removed after cure
• Aggressive cleanup damaging the membrane
• Thin membrane caused by aggregate sinking through the film

Do not assume that any dry sand is acceptable. Moisture, dust, gradation, mineral composition, and cleanliness can affect performance.

Patching Materials

Patching may occur below or above the moisture-mitigation membrane, depending on the system. That sequence must be determined before work begins.

A patch installed beneath the membrane must tolerate the slab moisture and alkalinity. A patch installed above the membrane must bond to the membrane or approved primer and cure without a porous-concrete absorption path.

Questions About Patching

• Is the patch installed before or after mitigation?
• Is it approved for the measured substrate moisture?
• What primer is required?
• What are the minimum and maximum thicknesses?
• Can the patch be feather-edged?
• What cure time is required before the next layer?
• Can it be used at cracks, joints, or moving transitions?
• Does it contain gypsum or another moisture-sensitive component?
• Will the warranty include the patching material?

Self-Leveling Underlayments

Self-leveling underlayments contain water and may require a primer to bond to a nonporous membrane. Primer coverage, drying, underlayment thickness, flow, cure, and environmental conditions are critical.

A membrane that limits moisture from below can also limit drying through the bottom of the underlayment. The material must be suitable for drying primarily toward the exposed surface.

Excessive underlayment thickness, standing primer, low temperature, high humidity, or early covering can delay cure and trap moisture within the assembly.

Flooring Adhesives

Flooring adhesives may behave differently over a nonporous membrane than over absorbent concrete. Water or solvent cannot move into the substrate at the same rate, which can change open time, tack, working time, and cure.

The adhesive manufacturer should approve the membrane or the specified primer and state the correct trowel, spread rate, open time, working time, and flooring-placement procedure.

Adhesive Compatibility Questions

• Is the adhesive approved over the exact membrane or primer?
• Is the receiving surface considered porous or nonporous?
• Which trowel notch is required?
• Must the adhesive remain wet, become tacky, or dry before placement?
• What temperature and humidity limits apply?
• What is the working time over the nonporous surface?
• When may the installed flooring receive rolling, traffic, or loading?
• Does the adhesive tolerate alkalinity or moisture at seams and edges?
• Are rolling and weight requirements different over the membrane?

Resinous Coatings Over Mitigation Membranes

A resinous floor coating may require chemical adhesion within a recoat window or mechanical adhesion to an abraded or aggregate-broadcast surface.

Even when both products are epoxy, they are not automatically compatible. Differences in curing agents, additives, surface energy, cure stage, blush, and formulation can affect bonding.

Confirm the Following

• Approved primer or direct-to-membrane application
• Minimum and maximum recoat time
• Surface cleaning and abrasion after the recoat window
• Required aggregate broadcast
• Minimum and maximum application temperature
• Compatibility with decorative flakes, mortar, or quartz systems
• Resistance to the intended chemicals and cleaning processes
• Total system thickness and cure schedule

Recoat Windows

A recoat window is the period during which the next layer may be applied using the manufacturer's specified procedure. Early application can disturb an uncured membrane. Late application can result in poor intercoat adhesion.

Recoat time is affected by temperature and sometimes humidity. A time printed on the data sheet may apply only at a stated temperature.

Surface Blush and Contamination

Some resin materials can develop haze, blush, surface film, or exudate during cure. Dust, construction traffic, condensation, oils, and cleaning residues can also contaminate the membrane.

Applying the next layer over a contaminated surface can cause intercoat delamination. Follow the manufacturer's cleaning and preparation procedure. An unapproved solvent wipe can spread contamination or leave residue.

Materials From Different Manufacturers

Combining products from different manufacturers can divide responsibility. One manufacturer may approve the bond to the membrane but not the finished flooring. Another may approve its adhesive only over a specific primer.

Obtain written compatibility statements that identify the exact products and sequence. A statement that a product is “generally compatible with epoxy” is not equal to project-specific approval.

Written Approval Should Identify

• Exact manufacturer and product names
• Order of application
• Surface preparation between layers
• Primer and aggregate requirements
• Application rates and thicknesses
• Minimum and maximum recoat intervals
• Environmental limits
• Cure and return-to-service requirements
• Applicable warranty coverage and exclusions

Mock-Ups and Bond Tests

A mock-up can demonstrate handling, appearance, coverage, cure, and initial adhesion between system layers. It can also establish the approved installation sequence.

When adhesion testing is required, determine the method, location, quantity, cure time, acceptance strength, failure plane, and repair procedure before testing.

A successful small-area test does not guarantee long-term performance under continuing moisture, traffic, chemicals, movement, or thermal cycling. It supplements—not replaces—written product qualification.

System Compatibility Review Process

1. List every material. Identify exact products from concrete repair through the finished surface.
2. Collect current technical documents. Obtain data sheets, application instructions, safety data, and warranty terms.
3. Compare substrate requirements. Verify that each layer is approved over the material below it.
4. Resolve conflicting instructions. Do not choose one requirement without written agreement from responsible parties.
5. Confirm recoat and cure timing. Build realistic intervals into the project schedule.
6. Confirm environmental limits. Use the most restrictive applicable requirement.
7. Review service exposure. Confirm traffic, chemicals, temperature, washdown, sanitation, and maintenance compatibility.
8. Obtain written approvals. Record manufacturers, products, sequence, preparation, and warranty responsibility.
9. Prepare a mock-up when required. Document the accepted materials and procedure.

Common Compatibility Failures

System Installation Records

Documentation should follow the assembly layer by layer. Record which material was installed, where, when, and over what surface condition.

Record the Following

• Exact product names and manufacturers
• Batch, lot, and expiration information
• Application area and floor-plan reference
• Condition of the preceding layer
• Cleaning, sanding, primer, or broadcast preparation
• Mixing and application times
• Coverage rates and thicknesses
• Air, surface, humidity, and dew-point readings
• Minimum and maximum recoat times
• Observed contamination, defects, and repairs
• Manufacturer or inspector approvals
• Photographs before each layer is covered

Contractor Compatibility Checklist

• Every layer in the system has been identified by exact product name.
• Each product is approved over the material beneath it.
• Required primers and aggregate broadcasts are identified.
• Preparation between every layer is documented.
• Minimum and maximum recoat intervals are scheduled.
• The most restrictive environmental limits are being followed.
• Patches and underlayments are suitable for their installation location.
• Adhesives are approved for the membrane's porous or nonporous condition.
• Finished coatings are approved over the membrane or intermediate primer.
• Cracks, joints, edges, drains, and transitions have compatible details.
• Service chemicals and maintenance products will not damage the assembly.
• Multi-manufacturer approvals are in writing.
• Warranty responsibility and exclusions are understood.
• Each layer will be inspected and documented before being covered.

Knowledge Check

Technical References

Use the editions required by the project specification and follow current written instructions issued by every system manufacturer.

• ASTM F3010-24 - Standard Practice for Two-Component Resin Based Membrane-Forming Moisture Mitigation Systems for Use Under Resilient Floor Coverings.
• ASTM F710 - Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring.
• ICRI Guideline No. 710.3-2022 - Guide for the Mitigation of Moisture in Concrete Floor Slabs.
• ICRI Guideline No. 310.2R - Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, Polymer Overlays, and Concrete Repair.
• ASTM D7234 - Standard Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers.
• Current technical data sheets, installation instructions, compatibility statements, safety data sheets, detail drawings, and warranty documents issued by the specified membrane, primer, repair, underlayment, adhesive, coating, and flooring manufacturers.

These references provide technical guidance but do not replace the project specification, applicable regulations, manufacturer requirements, or evaluation by a qualified professional. Final compatibility and installation decisions must be based on current documents, written approvals, and actual site conditions.