Waterproofing Membrane Vs. Moisture Barrier: Is There A Difference?

Given the variety of goods available on the market today that offer moisture management in some form, the best option for the job may not always be obvious. There are a few things to think about while selecting these kinds of products: How does a waterproofing membrane vs. moisture barrier differ? What materials are they each made of? What could make you choose one over the other? The simple answer is that it will vary somewhat from job to job. However, the following are some common points you can keep in mind.

What Are Waterproofing Membranes and Moisture Barriers?

Waterproofing only prevents liquid water from flowing from one area to another; it does not entirely deter water in a vapor state (though it can slow it down).

Moisture barriers and waterproofing are two distinct types of goods with quite different uses. To keep water from getting into a particular space, like a shower pan, you would employ a waterproofing membrane.

Moisture-reduction barriers manage moisture in a state of vapor. These membranes essentially prevent any vapors from passing through within the limitations of the particular product. They do so by filling the pores of the substrate, generally with epoxy or a polymer. These materials are ideal for treating high-moisture slabs or areas where there is a possibility of future high-moisture conditions.

What Are the Key Product Composition Differences?

Waterproofing membranes generally consist of a liquid rubber-like substance that is applied like regular wall paint. Although roller-applied membranes are the most prevalent, there are additional varieties that require reinforcing fabrics and meshes or application using a trowel rather than a roller. For instance, the HLM 5000 Roller 5G is a moisture-curing, single-component polyurethane elastomeric waterproofing membrane that can be rolled on surfaces. It is made for exterior, below-grade, or between-slab applications.

Moisture-reduction membranes come in a wide range of compositions, but some of the more common forms include epoxy, polyurethane, and polymer-based. Epoxy does a fantastic job at sealing open holes in concrete and creating a solid barrier to guard against the transmission of vapor. 

However, epoxies can be a little challenging to deal with, and the majority of these membranes will have moisture vapor emission limits. This brings us to other products, such as ones that use polyurethane.  Polyurethanes are pre-mixed and simple to apply with a paint roller, saving time and hassle. Lastly, polymer-based moisture-reduction membranes are widely accessible, affordable, and simple to install. One excellent option is our TREMproof 250GC waterproofing membrane. This is a high-solids, VOC-compliant, rapid-curing modified polyurethane waterproofing membrane. It is easy to apply on damp concrete, which reduces the delays related to rain or other moisture sources.

Final Thoughts

How do you decide, then? Determine whether you want to prevent “water” or “water vapor” infiltration. A waterproofing membrane is recommended whenever you need to prevent water from flowing from one place to another, such as when building a basin to contain water within a fountain. A moisture-reduction barrier will be the best option if you need to lay solid sheet vinyl over a high-moisture concrete surface.