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Interior wall, without OSB
Internal thermal insulation for a wall without OSB: Reflectiva Gold over the insulation, a service zone for building services and Reflectiva Multistrat before the lining.
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
When the wall has no OSB sheathing, Reflectiva Gold is installed directly over the insulation between the studs. This is followed by the battens or profiles, with the building services in the service zone, then Reflectiva Multistrat and the lining. Together, the two membranes occupy only 1.5 cm.
1.5 cm for both membranes
Gold is 10 mm thick and Multistrat 5 mm; together they add 1.5 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, while the insulation remains continuous and hermetically sealed. The space behaves like a thermos flask that preserves the indoor climate and temperature of the house.
Butt-jointed, not overlapped
The Gold strips are laid butt-jointed, without overlapping, and the joints are closed with Power Tape. The tape ensures the continuity of the membrane.
Installation steps
Click on the central image to enlarge it.
Products for this application
Warranty
- ✓Reflectiva Gold: 50-year warranty, service life of at least 50 years
- ✓Reflectiva Multistrat: 50-year warranty, service life of at least 50 years
- ✓Wolle: 50-year warranty (interior)
Frequently asked questions
What should I use to fix Reflectiva Gold?
With 14–16 mm staples or 1.5 cm wood screws.
Should I overlap the Gold strips?
No. The strips are butt-jointed, and the joints are sealed with Power Tape.
When should I choose the option without OSB?
When the wall has no OSB sheathing on the interior side. If the wall has OSB, the build-up is the one with two layers of Multistrat.
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.