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Robust Detail E-FC-4 is an acoustic solution for precast plank floors. This system exceeds the requirements of Approved Document Part E and when registered with Robust Details Ltd removes the requirement for on-site sound testing.

  • Exceeds Building Regulation requirements.
  • No need for sound testing if registered with Robust Details Ltd.
  • System uses Isorubber Base to reduce noise transfer, this is a tough, resilient acoustic mat that can withstand the rigours of the screeding process.
  • Purpose made Isoedge strip is used around the screed perimeter to eliminate flanking sound transfer.
  • No long term / short term deformation of acoustic layer.
  • Suitable for use with Under Floor Heating
  • Tried and tested solution which has been widely used since 2004.
Acoustic Performance:

As a Robust Detail the E-FC-4 system must consistently achieve a site test mean average:
Airborne Sound ≥ 50db (Dntw + Ctr)
Impact Sound ≤ 57db(Lntw)
This exceeds the Building Regulation (Approved Document Part E) requirements by 5dB in both cases.

Isorubber Base

Roll Size: 6mm x 1m x 10m
Roll Weight: 37Kg (14 Rolls per pallet)
Density: 635Kg/m3

Isoedge 6/260

Roll Size: 6mm x 260mm x 50m
Roll Weight: 5.2Kg (3 Rolls per Bag)
Density: 30Kg/m3

Isosonic Hangers Type C

Box Quantity: 100
Box Weight: 10.8Kg

Isosonic Ceiling Strip

Roll Size: 40mm x 25m
Roll Weight: 0.8Kg (10 Rolls in a Bag)
Density: 30Kg/m3

Isorubber Jointing Tape

Roll Size: 50mm x 50m
Roll Weight: 0.45Kg (24 Rolls in a Box)

Isorubber Base is a 6mm thick acoustic insulation that is laid beneath the screed, separating it from the precast plank and absorbing impact sound. A durable product with a density of approximately 635Kg/m3, Isorubber Base does not suffer from any deterioration of acoustic performance during the normal lifespan of a building. This is because it undergoes virtually no short term deformation or long term creep deformation under normal domestic loads.

With a recycled content of approximately 90% waste rubber, a Global Warming Potential of Zero and an Ozone Depletion Potential of Zero Isorubber Base provides a means of using problematic waste material to the benefit of the environment.

Isoedge 6/260, a purpose made edge strip, is fitted around the perimeter of the screed to separate it from the walls and reduce flanking sound transmission. With an adhesive backing strip, die cuts and markings to aid installation Isoedge 6/260 has been designed to eliminate installation errors at what is generally regarded as a problem junction.

No CFCs or HCFCs are used in the manufacture of Isoedge 6/260 and it has Global Warming Potential of 3 and Ozone Depletion Potential Zero.

A standard metal frame or Isosonic Ceiling system is also required to the underside of the precast plank. The type and depth of the ceiling are dependent on the precast plank thickness (please see the Robust Details handbook for further guidance on the options available).

The Isosonic Ceiling treatment utilises Isosonic Hangers Type C to separate the ceiling from the precast plank. Isosonic Ceiling Strip can be used around the ceiling perimeter to help reduce flanking sound transmission.

Isorubber Jointing Tape is a cloth tape designed to adhere to the Isorubber and Isoedge range of products.

The ever-popular E-FC-4 system was the first ever proprietary Robust Detail for concrete floors and has been widely used since its approval in 2004. It provides high performance and excellent design flexibility, being compatible with all masonry external flanking wall types. This makes it the natural choice for under screed Approved Document Part E compliance.

The E-FC-4 system consists of 6mm Isorubber Base fitted below a minimum 65mm sand & cement or minimum 40mm proprietary screed with Isoedge 6/260 separating the screed from the wall. The structural floor must be a minimum 150mm precast plank with a minimum mass of 300Kg/m2 per unit area. The joints of the Isorubber Base are lapped by 50mm and taped using Isorubber Jointing Tape.

This system can be used with all masonry external flanking wall constructions, including aircrete blocks (450 – 800Kg/m3, 1350 – 1600Kg/m3 & 1850 – 2300Kg/m3).

A metal frame ceiling with a minimum void of 100mm or an Isosonic Ceiling is also required. Both ceiling details are under drawn with a layer of gypsum based board (minimum 8Kg/m2).

The extensive site testing carried out for Robust Detail classification and the subsequent monitoring tests show that the E-FC-4 system can achieve 3 Code for Sustainable Homes Credits, subject to pre-completion testing.

As part of the E-FC-4 registration Thermal Economics provide site training to Site Managers and Screeders by experienced industry professionals who will instruct on installation procedures and answer any questions regarding your specific project.

The E-FC-4 system can also be, and is frequently, used in non Robust Detail specifications, subject to pre-completion testing.