Frequently asked questions about ETICS and the Class Mat Therm PSE system

What is an external thermal insulation composite system (ETICS)?

External thermal insulation (ETICS, in French ITE) means bonding — and, depending on the configuration, anchoring — insulation boards to the outside face of the walls, then protecting them with a reinforced base coat and a finishing render.

Class Mat Therm PSE is an ETICS on expanded polystyrene (EPS) boards for masonry or concrete walls, in new build and renovation. According to the DTA (French technical approval), it also improves the durability of the supporting wall by protecting it from external exposure. See the complete guide.

What are the components of the Class Mat Therm PSE system?

The system has seven layers, from the base of the façade to the finish:

0 — Profiles: aluminium base track, top stop profile, render stop profile. 1 — Bonding: Cm’EPS fix, Cm’Stirofix or Cm’Armatflex. 2 — Insulation: White EPS or Grey EPS. 3 — Fixing: TermoZ CS II 8 screw-in anchors. 4 — Reinforced base coat: Cm’Armatflex with glass-fibre mesh and corner beads. 5 — Fixat Pro Universal primer. 6 — Finishing render: Cm’AcryTop, Cm’SilikatTop, Cm’SiliTop or Cm’Granitplast.

What insulation thickness should I choose?

The thickness comes from a thermal calculation for each project: the DTA requires the wall to be calculated with the thermal resistance R certified by ACERMI for the chosen thickness.

Examples from the ACERMI certificates: White EPS 100 mm → R = 2.60 m²·K/W, 160 mm → 4.20, 200 mm → 5.25. Grey EPS 100 mm → R = 3.20 m²·K/W, 160 mm → 5.15, 200 mm → 6.45. White EPS is certified from 20 to 300 mm.

Where measures against fire spread on the façade are required, the DTA limits the insulation thickness to 200 mm for the solution it describes (§ 2.5).

White EPS or Grey EPS: what is the difference?

Grey EPS (graphite) insulates better at the same thickness: λD 0.031 W/(m·K), against 0.038 W/(m·K) for White EPS. At 160 mm, the certified thermal resistance is 5.15 m²·K/W for grey against 4.20 m²·K/W for white. For the same resistance, the grey board can therefore be thinner.

Grey EPS must be protected from sunlight during storage and installation (sheet or net letting through at most 30% of the solar energy). According to the DTA, it is either fully bonded or bonded in dabs or beads with immediate anchoring (before the adhesive sets), 2 anchors per board.

As products, both boards are classed Euroclass E; the B-s1, d0 class applies to the complete system (see the B-s1, d0 class). The DTA gives a calorific value of 0.70 MJ/m² per mm for white polystyrene and 0.75 MJ/m² per mm for grey.

What does the B-s1, d0 reaction-to-fire class mean?

B-s1, d0 is a Euroclass for reaction to fire under EN 13501-1: “B” means a very limited contribution to fire, “s1” low smoke production and “d0” no flaming droplets or particles.

According to the DTA, the Class Mat Therm PSE system is classed B-s1, d0 with all four finishes (Cm’AcryTop, Cm’SilikatTop, Cm’SiliTop, Cm’Granitplast) in two configurations: bonding with Cm’EPS fix or Cm’Stirofix and EPS of 15 kg/m³, or bonding with Cm’Armatflex and EPS of 13.4 kg/m³. No performance is determined for other configurations.

The insulation board on its own is classed Euroclass E. Restrictions may apply where regulations require measures against fire spread on the façade.

What are the ETA, the DTA and ACERMI?

ETA-25/0619: the European Technical Assessment of the Class Mat Therm PSE system.

DTA 7/26-1828_V1: the “Document Technique d’Application”, the French technical approval of the system, valid until 30 September 2032. Its scope covers mainland France.

ACERMI (the French certification body for insulation materials): the certification of the insulation boards, which sets their thermal conductivity and thermal resistance among other properties. White EPS: certificate 12/150/777; Grey EPS: certificate 15/150/1045.

The TermoZ CS II 8 anchors have their own ETA-14/0372. All documents can be downloaded from the documentation.

Can the system be used in Luxembourg?

Class Mat Therm PSE is a system under ETA-25/0619, also assessed in France by DTA 7/26-1828_V1 (French technical approval). The ETA is a European assessment; the DTA is a French approval whose scope covers mainland France.

For each project, check the requirements that apply to the building (thermal regulations, fire safety, municipal procedures). For a technical question about a project, contact us.

Which substrates can the system be installed on?

The DTA covers installation on flat vertical walls of masonry or concrete, in new build or renovation. The system can also be used to renovate an existing ETICS (over-insulation), within the fire-safety rules that apply to the building.

The adhesive mortars are intended in particular for brick, concrete and aerated concrete; Cm’Armatflex can also be used on blocks and cement or cement-lime renders. The substrate must be sound, dry, clean and load-bearing.

How long should you wait between layers?

According to the DTA, wait at least 24 hours after bonding before any further work. The reinforced base coat is applied in two passes of about 2.0 kg/m², with at least 24 hours of drying between passes; its dry thickness must be at least 3.0 mm. Allow at least another 24 hours before the next layer.

In cold and damp weather, the adhesive, the base coat and the finishing renders can take several days to dry, and they must not freeze within 24 hours of application. The mortars are applied between +5 °C and +25 °C. All steps in detail: installation guide.

How durable is an ETICS?

The DTA estimates the durability of the system at more than about twenty years, with maintenance. It notes that soiling in urban or industrial environments, or the growth of micro-organisms, may call for cosmetic maintenance within 10 years.

This is the assessment of the DTA, not a guarantee. Maintenance, renovation and repair are described in chapter 2.8 of the DTA, available in the documentation.

Which finishing render should I choose?

The system offers four ready-to-use finishing renders, all applied after the Fixat Pro Universal primer: Cm’AcryTop (acrylic binder), Cm’SiliTop (silicone binder, water-repellent and breathable), Cm’SilikatTop (silicate binder, mineral finish for façades that need good vapour permeability) and Cm’Granitplast (decorative mosaic finish for plinths and exposed areas).

AcryTop, SiliTop and SilikatTop come in 1.0, 1.5 and 2.0 mm grains, as a float or grooved finish. Full comparison: choosing a finishing render.

How do you calculate material quantities?

The calculator gives the complete list from the area, thickness, insulation and finish. The ratios used: adhesive 4.5 kg/m², reinforced base coat 4.0 kg/m², 4.2 anchors per m², mesh = area × 1.1 (50 m² rolls), primer 0.2 kg/m², finish from 2.0 to 3.0 kg/m² depending on the grain. One 1200 × 600 mm board covers 0.72 m².

These quantities are indicative: they do not replace the DTA, the technical data sheets or the project-specific design.

Which anchor length is needed?

Minimum length = insulation thickness + 10 mm of adhesive + thickness of any existing render + 25 mm of anchorage. Then take the first TermoZ CS II 8 length that is equal or longer (95 to 455 mm, in 20 mm steps). Example: 160 mm insulation on an unrendered wall → 160 + 10 + 25 = 195 mm → TermoZ 195.

Drill Ø 8 mm, effective anchorage depth 25 mm, flush or countersunk installation. At least 3 anchors per 1200 × 600 mm board; the exact number is checked against ETA-14/0372 and the actual substrate. The calculator picks the length automatically.

Where can I find the technical data sheets and SDS?

The DTA, the ACERMI certificates and the technical data sheets (TDS) of every product can be downloaded from the documentation, one by one or as a ZIP per layer. The documents are in French. Safety data sheets (SDS) are coming soon.

Are there subsidies for façade insulation in Luxembourg?

The Luxembourg government publishes its energy-renovation subsidies (the “Klimabonus” scheme) on guichet.lu. The conditions, amounts and procedure are described there and may change: check the official Klimabonus page on guichet.lu before starting a project.