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 insulation such as mineral wool or foam panels held in place using a studwork frame.

Key Points – Internal Wall Insulation:

  • Is generally cheaper to install than external wall insulation
  • will reduce the floor area of any rooms in which it is applied (the thickness of the insulation can be up to around 150 mm)
  • Can be disruptive as works are internal
  • Requires skirting boards, door frames, radiators and external fittings to be removed and reattached
  • Intermediate floor voids need to be insulated to stop damaging cold spots
  • Can make it hard to fix items to inside walls without puncturing the membrane – although special fixings are available
  • Needs any problems with cracking, penetrating or rising damp or poor mortar joints to be fixed first
  • Should not insulate one side of a pair of semidetached houses