Thursday's #MAPEITechTip: Can any patching compound or self-leveler be used under the Moisture Control System?

Due to time and budget constraints, project managers are always looking for ways to improve their bottom line—without compromising system performance over the service life of the installation. Moisture Control Systems have offered this edge, permitting moisture sensitive floor coverings to be installed, where previously a job may have been halted until an alternative solution was found—a project can continue on schedule, saving time and money.

But even with these systems there are some considerations that must be looked at. Although these 100% solid epoxy systems work well to control the MVER (moisture vapor emission rate), they aren’t designed to correct imperfections and depressions in the concrete substrate. For these moisture control systems to work optimally, a consistent thickness of a homogenous coating across the entire surface is required to effectively control the MVER.  So often it is necessary to make some repairs to the concrete substrate prior to applying the 100% epoxy system—but can you use any self-leveler or patching compound?

In a word, No, only patching compounds or self-levelers formulated for exterior applications or high MVER should be used to make repairs in the substrate prior to applying a moisture control system. If interior use cementitious patches or self-levelers are applied to a concrete substrate with a moisture vapor drive, they could degrade and fail under the moisture barrier system—causing additional time and money to remove and replace the failed patch or self-leveler.

MAPEI makes both a patching compound and self-leveler that can be applied prior to application of a moisture control system without breaking down or degrading under the coating:

1. Cementious Self-Leveling Underlayment: MAPEI’s Ultraplan Extreme 2 is specifically formulated for the resurfacing of horizontal surfaces where the building core & shell are still open to the environment or not under HVAC. Although not an exterior rated product, it is not affected by exposure to water or freezing temperatures and has no MVER limitations. Due to the MVER, it is important also to use a primer suited for the application, in this case either ECO Prim Grip or Primer T can be used before installing this self-lever.

2. Cementitious Patching Compound: MAPEI’s Mapecem Quickpatch is a fast-setting patching compound rated for both interior/exterior applications. It can be applied from featheredge to 3” (7,5 cm) for ramping or filling of depressions, or ‘bird baths’.

Have you ever wondered what is a ‘Thixotropic’ mortar?—this will be our topic for discussion Thursday the 28th of May.