When considering moisture mitigation systems, there are many different options. Let’s start with the assumption that moisture mitigation was specified and even a particular system was called out. Now we can look at the different types of systems that may be encountered:
- Poly sheeting (plastic)
- Loose lay sheets (infused paper type)
- All-in-one adhesives
- Typically, 6 mil plastic with overlapped and sealed seams and run up the wall. Only suitable for floating floor installations over a slab.
- Will completely stop vertical moisture movement, but there is an increased chance of microbial growth in the space between the space and the substrate.
Loose Lay Sheets (Infused Paper Type)
- Semi-rigid sheets with taped seams. Most often used under LVT/LVP (float and glued).
- Varying moisture limits depending on the system installed, but holds the same concern of an increased chance of microbial growth in the space between the plastic and substrate.
- Designed to penetrate the capillaries of the concrete. Generally, requires an absorbent substrate (per ASTM F 3191). Can be water-based, urethane-based, or silane-based in formulation.
- Varying limits. Penetrating systems become part of the substrate, blocking or slowing moisture in the slab before it can reach the top.
Film Forming Systems
- Two-component epoxy systems are the most common option and have decades of proven success. There also are one-component urethane and silane-based options that act more like a hybrid with some penetration and some film-forming properties.
- Varying limits. Purely film-forming systems require a specific mechanical concrete surface profile (typically CSP #3) obtained by shot/bead blasting. The film thickness also is critical to the performance.
- These types of systems primarily are urethan-based, but there are silane-based systems as well. They are applied in a liquid state and cure to a solid state.
- Varying limits. Substrate profile and preparation are critical and may have limited options for surface treatment.
- All-in-one adhesive systems. Primarily for wood flooring installation.
- Varying limits. Can be effective. Highly increased consumption or adhesive. More difficult installation. Most require 100 percent transfer for warranty, which can be incredibly difficult to achieve.
All of the mentioned systems will have different levels of moisture protection up to and including “no limits/no testing required.” It is important that you understand the type of system you are using. Ask their technical departments and representatives all your questions, and apply/install the system as intended, following all of the manufacturer’s instructions. Even “similar” systems can have very different properties, so again, contact that manufacturer’s technical team or your local representative and wear them out with questions before you begin.
Don Jewell is the head of technical for Loba-Wakol LLC in Wadesboro, North Carolina. He can be reach at email@example.com.