Internal thermal insulation : lining with insulation behind plasterboard fixed to a framing system

Semi-rigid product

Internal thermal insulation is a very widely used solution today. Wall insulation reduces energy consumption, but it also improves building comfort by removing the 'cold wall' effect we feel close to an uninsulated wall, and by limiting surface condensation, especially in corners.

This technique of using an insulation product as a lining in conjunction with a framing system is described in NF DTUs 25.41, 20.1 and 23.1 for more traditional insulation products, and in the Technical Assessments and Technical Application Documents for non-traditional insulation products.

Regardless of the type of installation used, the product must be semi-rigid to limit the risk of the material settling inside the partition over time. This performance is clearly shown on the ACERMI product certificate : "semi-rigid product » or Level L2 certified in the ISOLE classification*.

If the product is not semi-rigid, it must be accompanied by a Technical Assessment setting out the precautions to be taken in use.

Insulation products in direct contact with the supporting wall (with no air gap or breather membrane) may be absorbent. It must not be possible for moisture from the wall to penetrate the absorbent insulation product and enter the insulated space. This installation method is therefore possible only under certain conditions regarding the exposure of the wall concerned to rain and wind.

Non-absorbent insulation products may be installed in all possible configurations, whether or not it is in contact with the supporting wall. This performance is clearly shown on the ACERMI product certificate : performance WS or Level O2 certified in the ISOLE classification.

Once the insulation product has been correctly selected, all that remains is to follow the recommendations set out in DTU 25.41 or the process Technical Assessment / Technical Application Document for the other components in order to achieve long-term high insulation performance!

(*) ISOLE classification :

  • I : Mechanical properties under the effects of compression
  • S : Resistance to differential movements
  • O : Water resistance
  • L : Mechanical properties for cohesion and bending
  • E : Ability to withstand water vapor