Custom Audio Designs Ltd 

IsoRubber | GM-FF | Screed | Iso Floor

acoustic screedacoustic screedacoustic screedacoustic screedacoustic screed


  • Studios, gyms, industrial and residential.
  • Can be used to exceed Building Regs.
  • Suitable for timber or concrete sub-floors.
  • Can be used under timber, light-weight or full-weight concrete.


  • Easy Installation.
  • Significantly increases airborne and impact sound insulation.
  • Low natural frequency down to 15Hz.
  • Can be loaded up to 7kg/cm² (690 kPa).
GM-FF superior impact isolation mat

GM-FF superior impact isolation mat92% Recycled


GM-FF is made using compressible elastomer technology. Compressible elastomers are a completely different technology than vulcanised rubber. Typically vulcanised natural rubber or neoprene is defined as incompressible. This means it requires high loadings in order to obtain some static deflection to provide for any vibration isolation. These types of systems simply do not work in buildings where high floor loading is neither available or desirable. In a similar manner, fibreglass isolators are comprised of rigid particles which loose elasticity when compressed. The end result of this material is a dramatic degradation of performance over time.

Compressible elastomer technology allows for low natural frequency at low loads. Due to the suitability of low loading, the rubber can cover the entire floor surface, providing consistent performance throughout. Vulcanised rubber isolator systems require the isolators to be carefully positioned and extra isolators are often needed depending on weight and position of equipment. This requires additional layout planning, installation and costs.

GM-FF is supplied with a moisture barrier. There is no need for any plywood formwork the material is simply rolled out, with joints taped. The concrete can be poured directly onto it. The only additional accessory required is an edge perimeter flanking isolation strip.

gm ff installation steps
gm ff cross section showing edge detail perimeter isolation stripgm ff cross section showing edge detail perimeter isolation strip
gm ff loading chart showing natural resonant frequency
gm ff natural frequency
gm ff penetration details for pipes and services
Tensile Strength:240 kPa minimum
Elongation at Break:60% minimum
Compressibility:@ 345 kPa = 15% / recovery 85% minimum
@ 690 kPa = 20% / recovery 85% minimum
Type A Hardness:30 durometer
Temperature stability:-40°C to +115°C
FF2513+10mm plywood150mm concrete slab5755 5014147
FF0660mm screed140mm structural concrete595226F289-41701
FF1060mm screed140mm structural concrete595126F292-41702
FF1760mm screed140mm structural concrete604928F293-41702
FF2560mm screed140mm structural concrete614730F296-41702
FF25100mm concrete140mm structural concrete704532F943-41992
FF50100mm concrete140mm structural concrete724335F920-41970
FF75100mm concrete140mm structural concrete734136F921-41970
FF252x12mm plywood200mm concrete slab6053 B3498.14
FF252x13mm plywood200mm concrete slab6349 B3498.15
gm ff roll sizes and weights

All information contained in these details is given in good faith but without warranty.
Custom Audio Designs reserves the right to alter the specifications of any product without notice.
©Custom Audio Designs