What is Internal Wall Insulation (IWI)?

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Internal Wall Insulation (IWI) is applied to the internal walls of a building. It typically consists of dry lining in the form of pre-insulated plasterboard or built-up systems using fibrous insulation such as mineral wool held in place using a studwork frame.

Key Points – Internal Wall Insulation:

  • is generally cheaper to install than external wall insulation
  • will slightly reduce the floor area of any rooms in which it is applied (the thickness of the insulation is around 100mm)
  • can be disruptive but can be done on a room by room basis
  • requires skirting boards, door frames and external fittings to be removed and reattached
  • can make it hard to fix heavy items to inside walls – although special fixings are available
  • needs any problems with penetrating or rising damp to be fixed first