Kalamua, the first ready-to-use coating specially designed for bio-sourced surfaces, is winning over Parisian facades

The renovation focused on a combination of solutions adapted to old buildings: BATICHANVRE BL-TS®, a lime specially designed for the production of hemp concrete on plaster-filled supports, and KALAMUA®, the ready-to-use finishing coating suitable for hemp blocks and concrete.

This complex brings aesthetics to the building, while guaranteeing thermal and sound insulation.

Created in 2023 by SAINT-ASTIER® R&D, KALAMUA® is the only ready-to-use, machine-sprayable coating on the market, designed for bio-sourced block and concrete substrates. It respects the nature of the substrate, promotes hygrometric exchanges and, above all, remains easy to apply, as Anthony ASSUNÇAO, Manager of the Trezzentorres company in charge of the site, attests: “It is applied in two coats, wet on wet, without any prior application of undercoat. It dries in just 6 hours (compared to several days with a traditional coating), it provides invaluable time savings.”

When respect for history and improved thermal performance meet

The building, a testament to two historical eras, features a first façade built in 1620 under Louis XIII and a second dating from the time of Louis XVIII. Located in the Bastille district, near Place des Vosges in Paris, Laurence Renault, the architect in charge of the renovation and insulation work, says: “We went from discovery to discovery.”

“For these old plaster facades made of rubble and timber framing, and after a DPE (Energy Performance Certificate), it was necessary to review the insulation of 15 windows which had to be replaced. We therefore replaced all the timber framing, particularly along the rainwater downpipes; because the more we dug, the more the damage appeared,” explains the project manager.

Lime: an essential solution for this renovation

Faced with the specific challenges posed by this historic building, the choice of BATICHANVRE® BL TS, a lime specially formulated by SAINT-ASTIER®, quickly became the obvious choice for filling the hemp concrete walls.

This solution is perfectly suited to thermal and acoustic insulation, and to ensure indoor air quality thanks to its breathability and perfect permeability to water vapor (essential for the timber-framed parts of the building). In addition, BATICHANVRE® BL TS is perfectly compatible with plaster-filled substrates.

An ultra-high-performance coating and time savings on site

More than ever, eco-construction and home renovation must respond to, or even anticipate, future climate and energy challenges.

It is with this in mind that SAINT-ASTIER® has developed KALAMUA®, the first ready-to-use, sprayable single-layer coating, specifically designed for hemp block or concrete walls.

For Anthony ASSUNCAO, president of the TREZENTORRES company, which employs up to 70 workers on the 120 renovation projects carried out each year in the Ile de France region, Paris and the surrounding region, “KALAMUA® is the only coating that can be applied to lime/hemp. It can be recoated more quickly, is lightweight and very easy to apply, thanks to its creamy composition; it is a real plus for applicators.”

The first pass is applied over a thickness of 8 to 12 mm, in which a 10 x 10 mm square mesh glass fibre mesh is pressed down without delay, observing a vertical and horizontal overlap of at least 10 cm between each pass.

Tissues (fiberglass mesh) must also be glued to specific points (door frames, window frames, etc.).

Then, the second coat is applied – at a thickness of 8 to 12 mm – as soon as the first coat has firmed up and up to 24 hours after the first application.

“Once finished, the KALAMUA® coating has a maximum thickness of between 15 and 20 mm. For the final appearance, KALAMUA® is scraped and then sponge-troweled to avoid closing the surface and allow it to breathe,” the entrepreneur rejoices.

Thanks to this solution, the renovation, which began in January, is progressing according to schedule, illustrating the efficiency and performance of this innovative product, even in a complex and demanding construction site.