Densima – 37mm
High performance
thin insulation

Aluthermo® Densima


Insulation, vapour barrier and breather membrane combined in one product.
Made thicker to comply with European standards,
it is the perfect insulation for your roof renovation.

EPC certified.

How does the insulation Densima® work ?

DENSIMA is non symmetric and composed of the following compressible successive layers:

  1. an upper reflective and highly vapour permeable membrane
  2. a 37 mm thick, compressible layer of moisture-proof polyester fiber
  3. a layer of bubbles of dry air enclosed in polyethylene
  4. a lower film of pure aluminium, 30 microns thick, treated against oxidation

aluthermo densima

The upper reflective membrane reflects the solar radiation in summer and improves comfort by reducing the risk of overheating whereas the lower film of aluminium returns the thermal radiation in winter. The core of the insulation, composed of a polyester wadding and a layer of dry, stable air trapped in a bubble film effectively slow the transfer of energy by conduction.

DENSIMA is used as a reflective breather membrane for roofs when there is no insulation material between the rafters.



  • EPC & 2020 certified
  • Breather membrane, insulation and vapour barrier all in one
  • Multi-reflective and multi-layer with a reinforced thermal and acoustic performance
  • Reduces thermal bridges
  • Easy to install as it is welded across nits entire surface
  • Self-adhesive overlap included


Technical characteristics


Dimensions of the roll 1,20 x 10 m
Surface area per roll 12 m²
Weight ± 1050 g/m²
Thickness ± 37 mm (EN823 à 25Pa)
Operating temperature range -40°C à +80°C
Fire resistance classification E (EN 13501)
Resistance to water penetration Tight W1 (EN 1928)
Thermal core resistance R = 1,02 m².K/W (EN 12667)
Thermal resistance, installed as a
breather membrane between 2 layers
of air with a ventilated outer air layer
and a non-ventilated inner air layer
R = 1,77 m².K/W (EN 16012)
Thermal conductivity λ = 0,036 W/(m.K) (EN 12667)
Thermal performance Up to 25% more effective than 200 mm of mineral wool (*)(**)
Emissivity of the upper membrane 0,18
Emissivity of the lower aluminium 0,05
Tensile strength:
in longitudinal direction
in transverse direction
340 (± 13) N/50 mm (EN 12311-1)
515 (± 10) N/50 mm (EN 12311-1)
Tear resistance:
in longitudinal direction
in transverse direction
340 N (± 6) (EN 12310-1)
415 N (± 10) (EN 12310-1)
Water vapour resistance

– Top layer
– Bottom layer

Zp > 33000 (± 7000) (m2.s.Pa)/kg

Sd = 0,061 m
Zp = 33753.109 m2.s.Pa/kg

(*) Performance data only valid for the installation between 2 air gaps without direct contact (see installation instructions of the product).
(**) Thermal performance measured by the Eliosys laboratory, comparing the energy consumption of a structure insulated once with Aluthermo and once with 200 mm of mineral wool (λ 0.040 W/m.K.). In the absence of consensus on the standard, this result is not considered in the calculation of the EPC or the obtaining of a subsidy. See the Eliosys test report on

Densima insulation applications

Installation of Aluthermo® insulation

Discover the application of Densima insulation. Insulation of the roof from the outside, thin and efficient insulation.

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