MEL-ROL LM is a single-component, water-based, polymer-modified liquid waterproofing membrane designed for below-grade vertical applications. This document provides a detailed overview of its features, uses, surface preparation requirements, application methods, and essential installation guidelines, based on manufacturer documentation from W. R. Meadows. The membrane is suitable for both new construction and remedial waterproofing projects on concrete or masonry block substrates, and can even be used on ICFs and “green concrete.”
Product Description and Key Features
MEL-ROL LM is formulated to provide a waterproof barrier with very low vapor permeability. Its superior elongation characteristics allow it to bridge minor cracks and maintain its integrity over time, preventing brittleness. The membrane forms a fully bonded layer, preventing water migration beneath the surface. It offers an alternative to traditional “peel and stick” membranes, reducing installation time through spray or roller application. The system can be further enhanced by incorporating protection courses, insulation boards, or drainage boards, and is compatible with PERMINATOR® vapor barriers for a composite waterproofing system.
Surface Preparation
Proper surface preparation is critical for successful application of MEL-ROL LM. All surfaces must be thoroughly cleaned, free of coatings, curing compounds, and frost. They should also be relatively smooth and structurally sound. Any bug holes, tie holes, large gaps, or cracks should be patched using MEADOW-PATCH® 5 or MEADOW-PATCH 20. Loose laitance, dirt, dust, loose stones, and debris must be removed by sweeping or blowing. Inside corners require a cove of BEM from W. R. Meadows prior to membrane application.
Shrinkage cracks less than 1/16″ (1.6 mm) should be pretreated with a 60-mil coat of MEL-ROL LM, applied in a 6″ (152.4 mm) width. Cracks exceeding 1/16″ (1.6 mm) require taping with DETAIL STRIP from W. R. Meadows before membrane application. For specific project recommendations, contacting W. R. Meadows technical services is advised.
Mixing and Priming
MEL-ROL LM is designed for direct use from the pail or drum, typically requiring minimal to no mixing. However, if water appears on the surface, thorough mixing with a low-speed mechanical mixer is recommended before application.
Priming may be necessary to reduce blistering on concrete surfaces. A thin coat of MEL-ROL LM diluted with water can be used as a primer, with a recommended dilution ratio between 4:1 and 5:1 (MEL-ROL LM to water). The primer should be thoroughly mixed with a mechanical mixer and applied to the entire concrete surface at a coverage rate of 100 – 150 ft.²/gal. (2.45 – 3.68 m²/L). The primer requires approximately one hour to dry, depending on temperature and environmental conditions.
Application Methods
MEL-ROL LM can be applied using either a roller or a spray application method.
Roller Application
For roller application, a ¾” (19.1 mm) nap roller is recommended. The membrane should be applied in two coats, each 30 mils thick. It is essential to allow the first coat to reach its initial set before applying the second coat.
Spray Application
When spray applied, a minimum coverage thickness of 60 mils wet (45 mils dry) is required. To achieve this thickness and prevent slumping, the membrane should be applied in two coats of 30 wet mils each. The second coat should be applied after the first coat has dried, typically within one to two hours.
Spraying Equipment Recommendations
The most effective spraying equipment for MEL-ROL LM is the Graco HydraMax 350 or the Graco GH833 Big Rig. The Graco heavy-duty texture gun is recommended, utilizing a 0.051″ (Graco GHD551) heavy-duty switch tip for optimal results. For spraying the primer coat, a smaller orifice tip, such as the 0.035″ (Graco GHD635), can be used. Reversible tips are recommended for easy cleanup. Detailed spraying equipment guidelines are available from W. R. Meadows.
Detailing and Footing Details
After surface preparation, detailing is crucial. A desired thickness of 120 mils is recommended for inside/outside corners, non-moving cracks, hairline cracks, around drains, and penetrations. The W. R. Meadows Waterproofing Contractors Handbook provides additional information on detailing procedures.
For footing details, DETAIL STRIP from W. R. Meadows is used for impaction sheet coverage. The strips are folded lengthwise and cut at the fold, creating 4 ½” (114.3 mm) strips. These are installed on either side of the rebar, with any excess material turned down on the face of the footing. Voids around rebars in the keyway should be filled with BEM before pouring the walls.
Water Table Considerations
In applications subject to a high water table, the incorporation of WATERSTOP EC PLUS from W. R. Meadows (or an approved alternative) is required in the wall design.
Cleanup Procedures
Proper cleanup is essential, particularly after spray application. Material should not be left in the pump, lines, or gun after finishing. Caution must be exercised to prevent solvents from contacting MEL-ROL LM in the sprayer, as this can break the emulsion and cause clogging. The system should be flushed promptly with water only (no soap) until the pump and hose are clear, requiring approximately five gallons (18.9 L) of water. Aromatic solvents, such as xylene or toluene (approximately two gallons (7.6 L)), should be used for final flushing after the water flush. Mineral spirits, paint thinner, and gasoline must not be used for flushing. It is crucial to flush with water again to remove any remaining solvents before spraying MEL-ROL LM.
Protection and Backfilling
Vertical applications should be covered with PROTECTION COURSE, MEL-DRAIN™, or PERMINATOR from W. R. Meadows. MEL-DRAIN (type B with polymeric backing film) is specifically recommended. Refer to MEL-DRAIN INSTALLATION GUIDELINES for detailed instructions. Surfaces must be covered within 45 days of application.
Allow a 24-hour cure time for the membrane before backfilling.
Precautions
The provided documentation does not detail specific precautions beyond those related to solvent use during cleanup.
Conclusion
MEL-ROL LM provides a robust, water-based solution for below-grade waterproofing. Successful application relies on meticulous surface preparation, appropriate application techniques (roller or spray), and adherence to recommended cleanup procedures. Utilizing the specified spraying equipment and detailing methods, as outlined by W. R. Meadows, will ensure optimal performance and longevity of the waterproofing system.