Insulation material under rainscreen cladding

Insulation material under rainscreen cladding

Whether new or rehabilitated, external wall insulation systems with built-up cladding is increasingly used for its thermal performance and the variety of skins that it offers project owners for esthetic considerations (metal, terra-cotta, wood, resins).

L'isolant sous bardage ventilé est un système d'isolation par l'extérieur appliqué sur les parois planes verticales des bâtiments neufs ou existants. Il est composé d'un isolant, d'une ossature bois ou métallique fixée au gros œuvre et d'un parement extérieur ventilé sur sa face arrière.

Insulation material under rainscreen cladding is an external wall insulation system applied on the flat vertical walls of new and existing buildings. It consists of an insulation material, a timber or metal frame attached to structural work and external rainscreen cladding on its reverse side.
The most commonly used insulation products are panels or mineral wool rolls, although other types of insulation products are allowed (polystyrene, polyurethane, etc.). Insulation thicknesses commonly used vary between 100 and 150 mm.
The thermal insulation performance of the system depends on the thermal resistance of the insulation material and the fixing system that passes through the insulation (anchors, vertical racks, lugs, brackets, etc.). ACERMI certifies the thermal resistance of the insulation material.

Rules to follow

Panels/rolls of insulation material must be well joined to ensure continuity of the insulation.
Insulation can be installed as one or two superimposed layers with offset joints: one laid vertically and the other horizontally. In all cases, it is important to make sure that the thickness of the ventilated air space to the outside is at least 20 mm.

Durability and performance during installation

Insulation material may be exposed to rain during its installation. It must therefore have suitable water resistance. Although it does not affect the mechanical resistance of the system, the insulation material used must support its own weight during installation.
The dimensional variations caused by temperature and humidity must not degrade the continuity of the insulation or obstruct or reduce the thickness of the ventilated air space behind the external cladding.
Finally, unless there is specific justification, the insulation product must not interfere with the spread of water vapor from the inside, so that water vapor reaches the ventilated air space to be released to the outside. To meet all these requirements for rainscreen cladding use, ACERMI-certified insulation materials are classified I1 S1 O2 L2 E1.
Currently, 78 ACERMI certificates are available and downloadable from the website for this use.
Once the insulation product has been selected, all that remains is to follow the installation guidance (Building Code of Practice (DTU), Technical Appraisals, etc.) to achieve effective and durable thermal insulation.

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