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.


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

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

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

Dimensions of the roll 1,20 x 10 m
Surface area per roll 12 m²
Weight ± 1050 g/m²
Thickness ± 37 mm (EN823 at 25Pa)
Operating temperature range -40°C to +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

On the roof, from the outsideIcon_Toiture-extérieur