Insulation packages for rafters 15 cm deep
Published on 06.06.2025 · Isoflect Insulation technical team
Excellent performance in only 15 cm
Isoflect System 10 systems – Real efficiency, without toxic additives
If you are working with a roof structure with 15 cm rafters, you are probably facing a difficult choice: you wish to achieve effective insulation without exceeding the constructional limit, yet without compromising on health or durability.
The solution? Isoflect System 10 systems for 15 cm, optimised with Wolle technical wool and a package of thermo-reflective membranes that multiplies the thermal performance. Not only do they achieve impressive thermal resistance values, but they do so safely, cleanly and without affecting the usable space.
Technical performance of the available configurations
| Configuration | R (m²·K/W) | U (W/m²·K) | λeq (W/m·K) |
|---|---|---|---|
| System 10 Premium+ – with Wolle P2100 and P800 | 7,527 | 0,133 | 0,0276 |
| System 10 Premium – with Wolle P1500 and P800 | 7,301 | 0,137 | 0,0285 |
| System 10 Medium+ – with Wolle P2100 and P800 | 7,227 | 0,138 | 0,0288 |
| System 10 Medium – with Wolle P1500 and P800 | 7,001 | 0,143 | 0,0297 |
| System 10 Basic+ – with Wolle P2100 and P800 | 6,623 | 0,151 | 0,0296 |
| System 10 Basic – with Wolle P1500 and P800 | 6,397 | 0,156 | 0,0306 |
R (m²K/W), thermal resistance: the extent to which the layer or assembly opposes the passage of heat; the higher it is, the better it insulates. What it means →U (W/m²K): how much heat passes through one m² at a difference of 1 °C between the interior and the exterior; the lower it is, the better (U = 1/R). What it means →λ (W/mK), thermal conductivity: how readily the material conducts heat; the lower it is, the better the material insulates. What it means →
All values are calculated for 15 cm of insulation between rafters, with the Isoflect membrane systems installed on the interior and/or exterior side, in accordance with the specification.
Components of the System 10 systems for 15 cm
Wolle technical wool:
Isoflect thermo-reflective membranes:
In the Basic and Basic+ configurations, the Phase 1 system (two Multistrat membranes + Gold) is omitted.
In the Medium+ and Basic+ versions, the Roof Pro membrane is not included.
Advantages of the Isoflect systems:
-
They do not allow mould to form
-
They do not lose their properties over time and do not settle
-
100% hydrophobic, yet breathable
-
They eliminate thermal bridges and reduce the risk of condensation
-
Safe for health – free from VOCs and formaldehyde
-
Non-irritant during installation and odourless
-
Recyclable and manufactured with a reduced environmental impact
-
Warranty for the entire service life of the building
Compare with other solutions
To achieve R = 7.527 m²·K/W, a conventional insulation would require:
-
Conventional insulation with λ 0.038: ≈ 29 cm
System 10 Premium+ achieves the same performance in only 15 cm – that is, half the space required by conventional insulation.
Discover all the packages for 15 cm here:
Build your system on isoflect.nl
Tailored consultancy: 0790 067 438
Free delivery | Returns within 90 days
Isoflect System 10 – The best choice for a safe, efficient and healthy roof.
Part of the complete guide: Insulating the habitable attic — cases, layers and thicknesses.
Not sure which Isoflect product suits you? See the complete map — which Isoflect product is installed in each area of the house or open the package configurator to find out exactly what you need and in what quantity.