/, Contextual, Cooling, Envelope, Heating, Long term, Owners, Physical environmental, Psychological/2.1.5 Adding or increasing external insulation in roofs

2.1.5 Adding or increasing external insulation in roofs

2.1.5 Adding or increasing external insulation in roofs


This measure consists in adding a layer of insulation to the exterior face of the roofs with the object of reducing their thermal transmittance. The measure is of great interest for 1 or 2-storey buildings. It should be initially rejected for high-rise buildings roofs or for which have a thermal buffer space, as lumbers or no conditioned spaces.


  • Minimum interference to the users of the building

  • The height of the rooms on the top floor is not reduced

  • Surface temperature higher than the dew point of the indoor environment, sufficient to avoid condensation

  • All the thermal inertia is used

  • In sloping roofs, the external insulation enables the recovery as habitable of the under roof spaces, increasing the useful surface of the building

  • In flat roofs the insulation is useful to protect the waterproofing sheet, so the durability of waterproofing increases considerably.


  • Normally, executing the intervention through the outside, it will affect all of the building not just a flat in particular. Therefore it will be required, prior to the intervention, the express agreement of the community of neighbours.

Economic assessment

Initial investment: around 15 €/m2
Payback: around 2 years

References and best practices

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Environment or playable world:

  • Residential

  • Academic

  • Offices

  • All

Carried out by:

  • Public building users

  • Owners

  • Operators

  • All

Reduce consumption of:

  • Heating

  • Cooling

  • DHW

  • Lighting

  • Electric devices

Type of driver:

  • Physical environmental

  • Contextual

  • Psychological

  • Physiological

  • Social

Time framework:

  • Short term
  • Long term

Type of measure:

  • Envelope
  • HVAC
  • DHW
  • Lighting
  • Electrical devices
  • Other
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