Ceresit Ceretherm Solar Protect External Thermal Insulation: Dark Colours that Withstand the Sun
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Dark colours are the worst enemy of external wall insulation. Solar Protect makes them possible — with HBW, every shade can be controlled.
The system at a glance
- CERESIT CT 87 White Flexible | Fibre-reinforced base coat mortar
- CERESIT Thermo Universal | Fibre-reinforced base coat mortar
- CERESIT CT 327 | Glass fibre mesh
- GRAFIT EPS-80 | Graphite-based
- TERMOPOR EPS-80 | White
- CERESIT CT 16 | Acrylic primer
- CERESIT CT 110 SOLAR PROTECT
- CERESIT CT 76 SOLAR PROTECT
Solutions & Applications · External Thermal Insulation
Dark, intense colours are highly sought after in contemporary façade design — yet they are also the worst enemy of a thermal insulation system. They absorb more solar energy, overheat, fade and crack. The Ceresit Ceretherm Solar Protect system solves precisely this problem: it allows dark colours to be used on external wall insulation, thanks to UV Protect technology, which acts as an invisible shield against ultraviolet radiation.
The problem: why dark-coloured façades fail
Solar radiation poses a threat to the façade in two ways. Firstly, thermal stress: a dark surface can reach very high temperatures in the sun, creating stresses that lead to cracks. Secondly, photochemical degradation: UV radiation breaks down the polymer bonds within the render, resulting in fading and a loss of properties.
For this reason, in conventional ETICS systems, dark colours are either prohibited or subject to restrictions on the reflectance index (HBW). Solar Protect raises this limit.
The solution: UV Protect technology
At the heart of the system is the UV Protect technology in the top coat: light stabilisers — UV absorbers and free radical ‘scavengers’ — which are activated by solar energy and act as an invisible filter. They absorb harmful UV radiation and neutralise free radicals before they can damage the structure of the coating. The result:
- Enhanced resistance to ultraviolet radiation and high colour stability.
- A wider range of colours — including dark, vibrant shades.
- Self-cleaning, resistant to the absorption of dirt and water.
- Vapour-permeable and water-repellent — the façade ‘breathes’ but repels water.
- Resistant to biological contamination (fungi, algae).
- Extremely flexible, resistant to thermal stress and cracking.
Certification: ETA Ceresit Ceretherm Classic & ETA Ceresit Ceretherm Wool Classic.
The structure of the system
The Solar Protect system consists of six layers, from the masonry to the finished surface. The numbers correspond to the illustration:
Ceresit Ceretherm Solar Protect layering: ① masonry → ② bonding & EPS insulation → ③ reinforced base coat with glass fibre mesh → ④ quartz primer → ⑤ final render → ⑥ final coat of paint.
| # | Layer | Product |
|---|---|---|
| 1 | Substrate (masonry / concrete) | Load-bearing surface — clean, dry, stable. |
| 2 | Adhesives & insulation materials | Ceresit Thermo Universal for bonding, with EPS boards and fixing plugs. |
| 3 | Reinforced base layer | Ceresit CT 87 White Flexible base coat with CT 327 glass fibre mesh reinforcement. |
| 4 | Quartz contact primer | Ceresit CT 16 — primer for adhesion for the top coat. |
| 5 | Finishing coat (plaster) | Ceresit CT 76 Solar Protect — silicone-elastomeric render with UV Protect. |
| 6 | Finish colour | Ceresit CT 110 Solar Protect — elastomeric façade paint with UV protection. |
Where we recommend it
- Facades with dark or vivid colours — where conventional systems are not permitted.
- Buildings with high levels of solar exposure (south- or west-facing, unobstructed views).
- Projects requiring long-term colour stability and low maintenance.
- Environments with high humidity or biological contamination (fungi, algae).
The choice of colour for external wall insulation is not merely an aesthetic one — it is a technical decision. The colour’s reflectance index (HBW) determines how much solar energy the surface absorbs. Solar Protect allows for darker shades than a conventional system, but each shade has its own minimum HBW limit; always check the limit for the specific colour in the Ceresit colour chart.
Second point: the system is certified as a complete certified system (ETA). Replacing the top coat or primer with a product from another system invalidates the colour and UV guarantee. At ARGYNET, we specify the entire system and calculate materials per m².
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