Thermal insulation of roofs: what you should know

Thermal insulation of roofs is a profitable investment that increases comfort, energy efficiency and prevents damage to the building. The minimum insulation required to protect a building from thermal fluctuations will depend on the climatic zone in which it is located.

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What types of thermal insulation for roofs are there?

The arrangement of the insulating layer will vary depending on the type of roof, which will also determine the type of material to be applied.


Types of flat roofs and their layers

They have less than 5% inclination. The thermal insulation of flat roofs as well as their waterproofing are essential to ensure the well-being inside the building. Its main subtypes are, according to where the insulation is placed:

  • Traditional: waterproofing is applied over the insulation.
  • Inverted: the insulation goes on top of the waterproofing.

In addition, depending on the finish of their surface they can be passable or not, landscaped and flooded. Depending on their ventilation, they will be cold, hot or ventilated.

Regardless of its typology, the basic elements of a flat roof are:

  • Structural support.
  • The slopes.
  • The separating layers.
  • The insulation layers.
  • The waterproofing layer.
  • The finish coat and protection of the roof


Insulation methods for flat roofs

Hydrophobic expanded polystyrene (EPS-h) on the outside is a good alternative in case of sudden temperature changes. It avoids the appearance of condensation between the waterproofing layer and the support.

The polyurethane foam sprayed in situ is an option of simple application for flat roofs, which guarantees watertightness and does not present joints or overlaps.

Extruded polystyrene in sheet form is highly recommended and easy to install on rooftops, durable and water resistant. If it is placed on top of the waterproofing it will protect it and improve its durability. Expanded polystyrene is often used as insulation in the external thermal insulation system (SATE).

On the inside, laminated plasterboards can be applied together with mineral wool or polyurethane foam, which also provide acoustic insulation, although this means the loss of several centimetres in height. Another option for the interior is the extruded polystyrene sheet to cover with gypsum in situ or the laminated gypsum board.


Pictures application of polyurethane for roofs


Types of inclined roofs and their layers

They have more than 10% inclination. According to their number of slopes, will be a water, two waters, four waters, with skirts, pavilion or tamed, although there are other classifications depending on their structural support and the type of finish.

The fundamental elements of inclined roofs, regardless of their class, are:

  • Structural support.
  • Thermal and/or acoustic insulation.
  • Protection and finishing.


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Insulation methods for inclined roofs

They can be insulated on the outside with expanded polystyrene (EPS) or polyurethane foam. It is a quick application, which does not reduce the height of the building and does not affect the life inside, although it requires the placement of scaffolding. With less frequency polyurethane is sprayed in situ and even cork.

The interior insulation is more economical because it does not need scaffolding. Extruded polystyrene (XPS) or polyurethane foam sprayed in situ is usually used. It is quick to execute, dry, and does not necessarily involve lifting tiles. It is also necessary to pay attention to thermal bridges and assume that some centimetres of height will be lost. In addition, it presents the discomfort of having to prepare the interior space for the work of the installers.

Synthesia's range of polyurethane thermal insulation designed in situ for inclined and flat roofs is BBA (The British Board of Agrément) certified. Polyurethane is one of the most advantageous materials in the thermal insulation of roofs due to its elasticity, uniformity, resistance to UV rays and impermeability.


Pictures application of polyurethane for roofs



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