In most cases, yes — using both layers gives the best result.
The first layer (vibration damping) stops the metal and plastic panels from vibrating. Without this step, panels can still rattle and amplify noise, even if insulation is added on top.
The second layer (sound absorption or sound blocking) works on airborne noise — road noise, tyre noise, wind noise, and engine sound. It absorbs or blocks sound that would otherwise pass straight into the cabin.
If you use only the second layer, vibrations may remain.
If you use only the first layer, some noise will still get through.
When both layers are combined, they work together to deliver a quieter, more comfortable, and more solid-feeling cabin — especially for long drives, family trips, or vans used for camping.
For some small or budget-focused projects, one layer may still help, but we always recommend combining layers where possible for the best long-term result.