Low Energy House

Low Energy House - What is Rock Wool Insulation?

Rock Wool Insulation is manufactured from volcanic rock, mainly basalt and/or dolomite, which  is blended with coke and limestone

Rock Wool Cavity Insulation - Image Provided by Rockwool® Ltd

Production of Rock Wool Insulation

The materials are heated in a furnace to a very high temperature and then spun into fibres. They are coated with a resin binder water-repellent mineral oil, pressed into shape, and cured in an oven.

The melt runs onto a series of rotating wheels which spin the droplets into fibres; they are then coated with resin binder and water-repellent mineral oil.  The fibres fall onto a conveyor belt, where the loose mat is compressed to the required thickness and density, then passed into an oven where the binder is cured. Finally the Rock Wool insulation product is cut into rolls or slabs.

Recycling Rock Wool Insulation

An increasing proportion of Rock Wool insulation is now produced from recycled material from slag, a waste product from blast furnaces.

Physical Qualities of Rock Wool Insulation

Rock Wool insulation is denser than glass mineral wool and is made up of short strands which give it high compressive strength. It will withstand continuous temperatures up to 850 degrees C and is non-combustible.

Blown Rock Wool Insulation - Loft Insulation - Image Provided by Rockwool® LtdRock Wool Insulation Available for Thermal Insulation

Rock Wool insulation is available in a range of formats, dependent on the degree to which it was compressed during manufacture and its designated end-use

  • Loose fibre for hand filling or for blown cavity insulation
  • Quilt rolls for insulating lofts, lightweight structures and within timber framed construction
  • Batts (slabs) for complete cavity fill of new masonry walls
  • Semi-rigid slabs for partial cavity fill of new masonry walls
  • Rigid slabs for warm pitched roof and flat roof insulation
  • Rigid resin-bonded slabs for floor insulation

The Rock Wool mats and board insulation materials may be faced with aluminium foil to enhance their thermal properties.

Thermal Properties of Rock Wool Insulation

The thermal conductivity of mineral wool products for internal use ranges typically between 0.039 and 0.031 W/m K at 10 degrees C.

In the UK, when comparing the thermal values of insulating materials, it is important to remember that the best performing material is the one with the lowest thermal conductivity value

About Rock Wool Insulation - Loft Insulation - Wall Insulation