Weser launches Opti'Thermic®, the first lightweight 2-in-1 thermal threshold support

As a French designer and manufacturer, the company supports the transformation of buildings with aesthetic and technical solutions, adapted to the expectations of professionals as well as the challenges of sustainable construction.

With OPTI'THERMIC®, WESER launches the first lightweight 2-in-1 thermal sill on the market. Made of reconstituted stone, this unique element combines the functions of a sill and a threshold in a single solution, ensuring aesthetic continuity on the facade and simplifying construction site logistics. Thanks to the integration of structural insulation made of 100% recycled PET foam and ACERMI certified, OPTI'THERMIC® reduces thermal bridging at sills and thresholds by 25 to 40%, depending on the masonry and insulation configurations. Weighing 30% less than standard sills, at less than 31 kg/m, it reduces risks on construction sites and decreases the carbon footprint associated with transport. Available for openings from 40 to 310 cm and in monoblock form up to 160 cm, it is compatible with most window and door frames on the market.

Developed based on feedback from architects, distributors, builders, and general contractors, OPTI'THERMIC® meets market expectations: reducing heat loss, simplifying supplies, and ensuring the durability of structures. Distributed through specialized networks, OPTI'THERMIC® is suitable for both new construction and complete renovation projects.

OPTI'THERMIC® reduces thermal bridges by 25 to 40%

Sills and thresholds are a critical point in the building envelope and can represent several square meters of uninsulated wall space in a detached house. OPTI'THERMIC® reduces thermal bridging by 25 to 40%, depending on the masonry and insulation configurations. This performance is based on an optimized geometry combined with an insulating base specifically designed to adapt to all insulation solutions between 80 and 180 mm.

The material used is a 100% recycled and recyclable PET structural foam, ACERMI certified (no. 24/278/1647). With a declared thermal conductivity λD = 0,035 W/m·K and a density of 50 kg/m³, it offers a compressive strength exceeding 165 kPa and excellent mechanical and dimensional stability over time. Its closed-cell structure limits moisture penetration and ensures long-term insulation performance.

Simulations conducted by the independent firm Neotim confirm thermal conductivity (ψ) coefficients ranging from 0,021 to 0,029 W/m·K depending on the type of supporting wall (solid concrete block, hollow concrete block, or insulating brick). OPTI'THERMIC® thus achieves a performance of at least 0.045 W/(mK), the threshold associated with the BBC (Low Consumption Building) label. These results translate into a surface temperature increase of up to +3,5°C, which reduces cold spots around openings and improves comfort in all seasons. By limiting condensation zones, the sill also helps prevent mold growth. At the scale of a dwelling, this reduction in heat loss represents a potential saving of over 6% on the annual energy bill.

OPTI'THERMIC®, a universal product, suitable for all windows and doors

The OPTI'THERMIC® threshold sill was designed to integrate seamlessly into all construction methods, from new builds to complete renovations. Its 35 cm depth and the height of its base allow it to accommodate all insulation solutions between 80 and 180 mm, including thin-slab floors. Available for openings from 40 to 310 cm and in monobloc versions up to 160 cm, it meets the needs of most window and French door configurations. Its flush side drip edges and drip edge positioned 5 cm from the bare wall ensure long-lasting protection of the wall covering. Its design makes it compatible with most window and door frames on the market and allows for the installation of hinged shutters thanks to the discreet design of its side drip edges.

In addition, the OPTI'THERMIC® 40 threshold is a patented format specifically designed for entrance doors, with a depth of 40 cm and available in five monoblock sizes from 80 to 140 cm. This solution also meets accessibility requirements within the framework of Equivalent Effects (EE) solutions. OPTI'THERMIC® can be used throughout the country, including in seismic zones.

An innovative design to facilitate installation and simplify logistics

OPTI'THERMIC® was designed to reduce the physical strain of installation and simplify site management. Weighing 31 kg/m, 30% less than a standard reconstituted stone support (46 kg/m), it facilitates handling and helps reduce the carbon footprint associated with transport by nearly 30%.

This 2-in-1 concept (threshold support) also simplifies logistics and supply; one pallet is now sufficient to cover all standard openings in a house, limiting the number of stock items for distributors and businesses.

Its "T" design allows for installation by interlocking, without modification of the masonry, with implementation from the inside.

This design reduces handling risks, reduces risks on construction sites and divides installation time by three, representing a 60% saving for a single-piece element.

The format also incorporates a reservation at the front of the heel, which avoids the need for gluing (cutting) the joinery.

To meet the requirements of DTU 36.5, WESER offers universal brackets with three cutting lines, allowing adaptation to different insulation thicknesses with a single format.

They ensure the fixing of the support on windows with a distance of more than 0,9 m between frames and guarantee a compliant and secure installation.

These brackets complement the product range and allow for complete technical support for installers.

Velvet and Raw Stone: finishes that combine aesthetics and a unique feel

OPTI'THERMIC® is not limited to thermal performance. Aware of the importance of aesthetics in architectural projects, WESER offers two finishes adapted to different expectations.

The Raw Stone look restores the natural texture of cut stone and integrates easily into all styles of facades.

The Velvet finish, a truly unique feature of the range, is distinguished by its soft and unprecedented feel, particularly appreciated for the sensory quality it brings to windows and doors. Easy to maintain, this finish can be customized according to the RAL color chart, offering more than 200 possible shades to meet regional specificities and the most demanding aesthetic preferences.

The two finishes – Raw Stone and Velvet – are offered in 6 standard shades: off-white, grey, stone tone, cotton, slate and ivory.

This basic palette ensures visual continuity on the facades, while the Velvet finish expands the possibilities for customization.

OPTI'THERMIC®, a demonstrator of WESER's CSR strategy

By incorporating insulation made from 100% recycled PET into OPTI'THERMIC®, WESER is putting its environmental strategy into concrete action. This strategy aims for a 20% reduction in CO₂ emissions by 2030, the gradual replacement of natural aggregates with recycled materials, and the development of lightweight, low-carbon solutions. OPTI'THERMIC® thus exemplifies the integration of recycled materials into a high-performance building solution.

This insulating foam combines a thermal conductivity λD = 0,035 W/(m·K) with high mechanical strength (>165 kPa in compression). Its closed-cell structure ensures excellent moisture resistance and prevents mold and corrosion. At the end of its service life, the insulating base can be separated from the concrete to facilitate recycling and material recovery.

This insulation also stands out for its superior environmental profile: its carbon footprint is significantly lower than that of traditional polymer foams (EPS, PUR, PIR, XPS) and it benefits from an Environmental Product Declaration (EPD) certified by the Institut Bauen und Umwelt (IBU), in accordance with ISO 14025 and EN 15804 standards.

A WESER innovation fueled by listening to the field

In 2024, WESER conducted a SATISF'ACTION survey of 65 representative players in the sector: traders, builders of individual houses, general contractors, architects, economists and design offices.

These discussions confirmed the need for a universal thermal threshold support and highlighted the importance of criteria such as aesthetics and ease of implementation.
In parallel, WESER participates in standardization work within the Supports and Thresholds Commission of the Federation of the Concrete Industry (FIB), where the company contributes to the development of technical standards applicable to the profession.