View our Product FAQ for answers to common questions about GenieMat products.
An underlayment needs to be resilient and dense to efficiently isolate impact footfall and airborne noise. GenieMat RST meets both of these requirements in each available thickness. The thinner RST-02 and RST-05 are recommended when the ceiling below has resilient clips or resilient channel installed. When the ceiling below is fixed to the framing, then the thicker RST-10, RST-12, or RST-15 are recommended. The thicker GenieMat RST versions are also recommended when a higher level of performance in isolating impact footfall and airborne noise is required.
GenieMat RST has been tested to perform under most common floor finishes including, but not limited to, tile, stone, wood, laminate, vinyl, VCT, and carpet with installation directly to wood, concrete, and steel sub-floors. The GenieMat RST has also been tested to meet ANSI standard 118.12 as a crack isolation membrane as well as IAQ test ASTM D5116 for zero VOC.
Rubber underlayment will always perform best over or under concrete, either full pour or lightweight. Because of the extreme mass and rigidity of the concrete, the rubber is able to compress properly allowing the rubber to add significant resilience to an otherwise rigid structure.
Rubber underlayment will not perform over wood sub-floors as predictably as it will over concrete. There are two great ways to mimic the performance of rubber over concrete in a wood structure. The best way is to fix the structural deflection between the joists (read Fixing Structural Deflection). The other way is by layering approximately 7 pounds per square foot of material over the sub-floor or over the GenieMat RST. Layering directly to the sub-floor will help more with low frequency airborne and footfall impact noise transfer while layering over the GenieMat RST will increase the STC rating by at least a couple points with a slight reduction in low frequency performance. Any heavy material will work for layering, e.g. plywood, OSB, MDF, drywall, 3/4" lightweight concrete, or a cementitious board like HardiBacker. Layering several pounds per square foot of material over the GenieMat RST is not required, but recommended in order to maximize the performance of the rubber underlayment in a wood structure.
Layering also provides an opportunity to add more damping to the floor with a product like our Green Glue Compound. Including Green Glue Compound will add to the isolation of both impact footfall and airborne noise. Decoupling the ceiling below with GenieClips or resilient channel increases the value of the GenieMat RST in both concrete and wood structures. The highest rated floor/ceiling assemblies will have resilience in both the floor and the ceiling.
Read our article Maximizing Rubber Underlayment Performance for more detailed information.
If the joists below can be stiffened using stepped blocking, then layering can be avoided. Read our article Fixing Structural Deflection for more detailed information.