Specifying the correct adhesive for commercial rubber flooring is critical to ensuring long-term performance, mitigating moisture-related failures, and meeting indoor air quality standards. This guide details the technical requirements for adhesive selection, focusing on moisture tolerance, volatile organic compound (VOC) emissions, and compatibility with resilient floor coverings.
TL;DR
- Adhesive selection must align with the subfloor moisture condition, typically assessed via relative humidity (RH) testing in accordance with BS 8203.
- High-moisture environments require specialist moisture-tolerant adhesives or the prior application of a surface damp proof membrane (DPM).
- Two-part polyurethane (PU) adhesives offer superior bond strength and moisture resistance compared to standard acrylic or solvent-based options.
- VOC emissions from adhesives must comply with indoor air quality standards, such as BREEAM Hea 02, to ensure occupant health and safety.
- Compatibility between the adhesive, subfloor preparation materials (e.g., smoothing compounds), and the rubber flooring is essential to prevent chemical reactions or bond failure.
Understanding subfloor moisture and its impact
Moisture is the primary cause of adhesive failure in commercial flooring installations. When moisture vapour from the subfloor interacts with the adhesive layer, it can cause the adhesive to re-emulsify, leading to bubbling, lifting, and eventual failure of the floor covering. BS 8203 (Code of practice for installation of resilient floor coverings) mandates that subfloors must be tested for moisture prior to installation.
The standard method for assessing subfloor moisture in the UK is the use of a surface hygrometer to measure the relative humidity (RH) of the concrete or screed. For standard adhesives, the RH must typically be below 75%. If the RH exceeds this threshold, a surface damp proof membrane (DPM) must be applied, or a specialist moisture-tolerant adhesive must be specified.
| Moisture Condition | RH Threshold | Recommended Action |
|---|---|---|
| Dry | < 75% | Standard adhesive application |
| Damp | 75% - 85% | Moisture-tolerant adhesive or surface DPM |
| Wet | > 85% | Surface DPM mandatory |
Types of adhesives for commercial rubber flooring
The selection of adhesive depends on the specific requirements of the installation, including the type of rubber flooring, the subfloor condition, and the expected traffic load.
Acrylic adhesives
Acrylic adhesives are commonly used for standard commercial rubber flooring installations. They offer good initial grab and are relatively easy to apply. However, they are generally not suitable for areas with high moisture levels or extreme temperature fluctuations.
Two-part polyurethane (PU) adhesives
Two-part PU adhesives provide a high-strength, durable bond that is highly resistant to moisture and temperature changes. They are the preferred choice for heavy-duty applications, such as free-weights zones utilizing products like Titan, or areas subject to high dynamic loads. PU adhesives cure through a chemical reaction, creating a bond that will not re-emulsify in the presence of moisture.
Epoxy adhesives
Epoxy adhesives offer similar performance characteristics to PU adhesives, providing exceptional bond strength and chemical resistance. They are often specified for specialist applications where extreme durability is required.
Volatile Organic Compounds (VOCs) and indoor air quality
The emission of Volatile Organic Compounds (VOCs) from flooring adhesives is a significant consideration for indoor air quality (IAQ). High VOC emissions can contribute to "sick building syndrome" and adversely affect the health and well-being of building occupants.
Specifiers should select adhesives that comply with recognized low-VOC standards, such as the EMICODE EC1 Plus classification or the requirements of BREEAM Hea 02 (Indoor Air Quality). Low-VOC adhesives minimize the release of harmful chemicals during and after installation, ensuring a healthier indoor environment.
Compatibility and system warranties
Ensuring compatibility between all components of the flooring system is crucial for a successful installation. The adhesive must be compatible with the subfloor preparation materials (e.g., primers, smoothing compounds) and the rubber floor covering itself. Incompatible materials can lead to chemical reactions, plasticizer migration, or bond failure.
Specifying a complete system from a single manufacturer or utilizing products that have been explicitly tested and approved for use together is highly recommended. This approach not only ensures compatibility but also simplifies warranty claims in the event of a failure.
Application techniques and environmental conditions
The successful application of flooring adhesives requires strict adherence to the manufacturer's instructions regarding trowel notch size, open time, and working time. The correct trowel notch ensures the appropriate amount of adhesive is applied to achieve a secure bond without excessive squeeze-out.
Environmental conditions during installation also play a critical role. The ambient temperature, subfloor temperature, and relative humidity must be within the ranges specified by the adhesive manufacturer. Installing outside of these parameters can affect the curing process and compromise the bond strength.
Key takeaways
- Always conduct subfloor moisture testing in accordance with BS 8203 prior to adhesive selection.
- Specify two-part PU adhesives for heavy-duty applications or areas with elevated moisture levels.
- Prioritize low-VOC adhesives to ensure compliance with indoor air quality standards and promote occupant health.
- Verify compatibility between the adhesive, subfloor preparation materials, and the rubber flooring to prevent system failure.
FAQ
For standard adhesives, the subfloor relative humidity (RH) must typically be below 75%, as measured in accordance with BS 8203.
Two-part PU adhesives should be specified for heavy-duty applications, areas subject to high dynamic loads, or environments with elevated moisture levels where standard adhesives may fail.
High VOC emissions can contribute to poor indoor air quality, potentially causing health issues for building occupants. Specifying low-VOC adhesives mitigates this risk.
No, the adhesive must be specifically formulated for use with rubber flooring and compatible with the subfloor preparation materials to ensure a durable bond.
Applying adhesive outside the manufacturer's recommended temperature range can affect the curing process, leading to reduced bond strength or complete failure of the installation.
A surface DPM is required if the subfloor moisture level exceeds the tolerance of the specified adhesive, typically when the RH is above 75% or 85%, depending on the adhesive type.
The trowel notch size is critical as it determines the amount of adhesive applied. Using the incorrect size can result in insufficient bonding or excessive adhesive squeeze-out.
Open time is the period between applying the adhesive and when the flooring must be laid into it. Working time is the total time available to adjust the flooring before the adhesive begins to set.
Related resources
Specification summary Subfloor Preparation: Subfloor to be prepared in accordance with BS 8203. Moisture testing to be conducted via surface hygrometer; RH must not exceed 75% unless a surface DPM or moisture-tolerant adhesive is specified. Adhesive: Apply [Insert Adhesive Type, e.g., Two-part PU] adhesive, compliant with low-VOC standards (e.g., EMICODE EC1 Plus), using the manufacturer's recommended trowel notch size. Application: Ensure environmental conditions (temperature and humidity) are within the adhesive manufacturer's specified parameters during application and curing.