Description
MJS Sound Block Rubber SB310 is a 3mm high-density natural rubber underlay engineered specifically for laminate and timber floating floors, using a closed-cell structure that gives it genuine sound-absorption performance rather than just cushioning underfoot. The integrated golden-foil membrane on the underside is rated as a 100% vapour barrier, stopping moisture and moisture vapour transferring up from the subfloor into the flooring above when correctly installed and joined.
Acoustic performance is documented as a genuine before-and-after comparison rather than a single generic figure: the bare concrete slab alone rates L’nT,w (FIIC) 63 (35), and installing Sound Block Rubber underneath the floating floor brings that down to L’nT,w (FIIC) 47 (56) — a 16-point reduction (ΔL’nT,w). Lower numbers mean less impact noise transferring through the floor, so that 16-point drop is a meaningful, measurable improvement rather than a marketing figure.
Technical Specifications
| Thickness | 3.0mm + golden foil |
|---|---|
| Roll size | 10 lineal metres x 1m wide (10m² per roll) |
| Density | 880 kg/m³ |
| Floor rating L’nT,w (FIIC) | 47 (56) |
| Concrete slab rating L’nT,w (FIIC) | 63 (35) |
| ΔL’nT,w reduction | 16 |
| Water vapour transmission rate | 1.8g/m²/24hr (ASTM E96) |
| Water absorption (28 days) | 0.03mg/cm² (JIS 6767) |
| Compressive strength (25% compression) | 70kPa (ISO844) |
| Overlap | 50mm |
Where to Use
- Underneath laminate and engineered timber floating floors
- Over concrete or timber subfloors, subject to moisture testing
- Installations requiring documented impact-sound reduction
How to Apply
- Test the subfloor — confirm moisture content is below 14% for timber/particleboard, or below 80% relative humidity (or 4% by impedance meter) for concrete, per AS1884-2012 Appendix A.
- Prepare the subfloor — ensure it is dry, clean, smooth and free of sharp objects.
- Roll out the underlay — gold foil side down.
- Join adjacent rolls — remove the protective cover from the joining tape and roll the next length so the tape and flap seal together.
- Install the flooring — proceed with the engineered timber or laminate flooring once the underlay is fully laid.
Important Notes
- Not a waterproof membrane — it is not intended to protect against excessive or abnormal subfloor moisture.
- Store protected from moisture and direct sunlight prior to installation.
- The published acoustic ratings are site-specific and indicative; actual performance depends on the overall floor/ceiling system.
- Footwear with protruding surfaces should be avoided when walking on the underlay during installation, to prevent surface damage.
