Good thermal insulation is the first priority in the building. As oil prices rise, the standard of insulation must increase. This is a one-off spend as many areas of the house cannot be improved later. There is a wide range of insulation materials available.


  • Fibre glass wool
  • Rock wool
  • Expanded polystyrene
  • Foil backed polyurethane
  • Multi foil insulation materials
  • Spray-in foams (open cell and closed cell)


  • Cellulose (recycled newspaper)
  • Hemp
  • Sheep wool

The value of insulation is expressed as k value; the insulation value of a structure is quoted as u value. The lower these values, the better the insulation. Building control requirements are minimum standards and the house builder would be advised to go well beyond these.

Ease of installation is another important consideration as some good insulation products are difficult to install. Gaps left in insulation cause “cold bridges” and it’s effectiveness is compromised. Choose insulation which is practical on site and easy to install.

Insulating walls in block buildings
The range of options is daunting. It currently includes:

  • High quality insulating board
  • Full fill cavity
  • Dry lining the external wall
  • Making the cavity wider
  • Thermal blocks

Reinco has researched this and can provide comparative cost per m2 for given “u” values.

Stop Press: There are now excellent open cell foam and closed foam for a range of applications. These product combine insulation and airtightness.