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Interior wall, with OSB
Internal thermal insulation for a wall sheathed with OSB: two layers of Reflectiva Multistrat and a service zone for building services.
Technical content: Bogdan Ivănescu, graduate engineer, PhD candidate at the Technical University of Cluj-Napoca · updated on 16.10.2026
Three zones, each with its own role
A first layer of Reflectiva Multistrat is bonded to the OSB board, with the aluminium facing inwards. Over it comes the batten or profile framework, through which the building services are routed, then the second layer of Multistrat, with the aluminium facing outwards, and finally the lining. Together, both layers occupy only 1 cm.
Only 1 cm for both layers
Each layer of Multistrat is 5 mm thick, so the system adds a total of 1 cm to the wall thickness.
Emissivity 0.05
The aluminium face has an emissivity of 0.05 and a reflectivity of between 95% and 97%.
Emissivity: an emissivity of 0.05 means that the aluminium face radiates only 5% of the heat that an ordinary surface would radiate, and therefore does not give off heat by radiation. The lower it is, the better. What this means →Reflectivity: the proportion of the radiant heat reaching the membrane that is sent back. What this means →A space that serves two purposes
Between the battens or profiles there is room for building services, without interrupting the insulation, which remains continuous and hermetically sealed. The space behaves like a thermos flask that preserves the indoor climate and temperature of the house.
Joints closed with tape
The joints of both layers of Multistrat are sealed with adhesive tape (Power Tape). Overlapping the strips is not mandatory.
Installation steps
Click on the central image to enlarge it.
Products for this application
Warranty
- ✓Reflectiva Multistrat: 50-year warranty, service life of at least 50 years
- ✓Wolle: 50-year warranty (interior)
Frequently asked questions
Which way should the aluminium face?
The first layer, bonded to the OSB, has the aluminium facing inwards. The second, installed before the lining, has the aluminium facing outwards. In this way, both aluminium faces are oriented towards the service zone.
Do I need to overlap the Multistrat strips?
No. Overlapping is not mandatory; what matters is that the joints are sealed with adhesive tape.
How much room space do I lose?
The two layers of Multistrat together measure 1 cm (5 mm each), to which the batten or profile framework and the lining are added.
Why Wolle for the insulation between the studs?
Wolle is polyester fibre without added substances: no binders, no formaldehyde, no flame retardants. It is odourless, does not cause itching during installation and does not retain water. The semi-rigid boards do not settle within the wall, and the warranty covers settling and decomposition of the material.
What should I do if the insulation also includes a 5 cm layer?
The 5 cm layer (Wolle P800, boards or roll) is always installed first, before the 10 cm layer (Wolle P1500 or P2100). The 5 cm layer adheres very well to the porosity of the substrate and requires no anchoring whatsoever.