Multifoil Insulation: Categories & Role of Internal Foil Layers

A few years ago, it was very difficult to insulate the most conservatory areas of the home. Insulation materials used to be were thick and cumbersome, sometimes 10-15 cm thick. But, in recent years the construction industry had gone through a significant change in providing insulation to the home. Technological innovations have resulted in new materials, including thinner, more flexible and increased insulating properties. You can now install thermally dynamic multifoil insulation to the existing conservatory roof or wall, without losing much headroom at all.

multifoil insulation

Product Range

The Multifoil insulating material is divided into three distinct categories:

Reflective foils: Reflective foils are designed by laminating the reinforcing metal foils or plastic membranes on the board by using a reflective treatment. These foils are used:

  •    • Sarking of underlays
  •    • A supplementary layer is placed over the regular horizontal roof insulation 
  •    • Below the concrete ground floors as an impermeable membrane
  •    • Suspended ground floors that are draped over the joists 
  •    • Insulate the wall suspended in the vertical cavities 
  •    • To insulate from wrapping to ducting.
  •    • As vapour control layers
  •    • Fire protection

Laminated Membranes: Laminated membranes are flexible and composite materials having a series of polyethylene sheet, aluminum foil, mineral wool fleece and polypropylene membranes. Its thickness ranges between 3-30mm. Uses include:

  •    • Sarking of underlays 
  •    • Placing as an extra layer placed over the horizontal roof
  •    • Suspended ground floors that are draped over the joists 
  •    • Insulate the wall suspended in the vertical cavities 
  •    • To insulate from wrapping to ducting.

Laminated Boards: Laminated Boards are reflective foils laminated with rigid polyurethane, quilt or mineral wool boards or with extruded polystyrene. Its uses includes:

  •    • Flexible and rigid sarking insulation 
  •    • Ground floor insulation placed between the concrete slabs or the joists
  •    • Insulating the wall having structural framing or masonry leaves
  •    • To insulate from wrapping to ducting. 

Role of internal foil layers in Multifoil

The principle behind MLI is radiation balance. Popular thinking is, the thicker the insulation the warmer the house. But increasing the thickness disproportionately lowers the increase in thermal resistance. With increasing, thermal regulations walls and roofs will have to become thicker to deliver the required U value. So, the metal layers such as aluminium acts as an excellent conductor of heat and reflects 90% of heat radiation. It continuously reflects the heat in its different layers back and forth, with the same efficiency until it is eventually absorbed and conducted away.

The multifoil reflective are found in many insulation boards. So, buyers should look for their thermal performance, surface emissivity, thermal resistance value and accreditation from various standards before purchasing it.

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