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OPTI’THERMIC sill support: Your key to sustainable construction

Publié le 1 September 2025 - PRESS INFORMATION

WESER offers reliable, durable solutions to support building professionals in their projects. With its OPTI’THERMIC® range, the sill support specialist brings to market the first lightweight thermal sill support designed for energy efficiency in the home!

Reduces thermal bridges by 25% to 40%.

Today,optimizing the energy efficiency of buildings is a priority. With its integrated high-performance insulation, OPTI’THERMIC® reduces thermal bridges by 25% to 40%, depending on the configuration. This means savings of up to 6% on the energy consumption of a 106 m² house.
Theinsulation, selected from 100% recycled and recyclable materials, offers excellent thermal and mechanical stability, while being resistant to water, humidity and compression. It actively contributes to the fight against mold and condensation, guaranteeing long-lasting thermal comfort, summer and winter alike.

Suitable for all types of construction

This specific format, 35 cm deep, is particularly well-suited to interior insulation configurations, and is compatible with the majority of joinery systems on the market.
OPTI’THERMIC® is available for openings from 40 to 310 cm, in monobloc versions up to 160 cm, with gaskets available in all colors.
Thanks to its discreet joints, it integrates harmoniously with swinging shutters, while ensuring optimum protection of the façade via a drip system positioned 5 cm from the raw wall.

Light, virtuous, quick and easy to install

OPTI’THERMIC® weighs almost 30% less than conventional sills (31 kg/ml vs. 46 kg/ml), making on-site handling easier and significantly reducing the workload for installers.
Simple interlocking installation saves up to 60% of the time required for conventional sills. Designed to fit standard joinery and interior insulation configurations, its 35 cm depth eliminates the need for complex adjustments and crane operations.

The ideal entrance threshold

OPTI’THERMIC® 40 is also available in a door threshold version, and can be adapted to equivalent solutions for accessibility. Its design ensures efficient drainage of run-off water, preventing infiltration andpremature wear. It is available in 5 sizes (80 to 140 cm) to suit all configurations.

The choice of aesthetics

Because performance should never come at the expense ofaesthetics, OPTI’THERMIC® is available in two finishes:

Pierre Brute, inspired by cut stone,
Velvet, soft to the touch and easy to care for.

Available in 6 standard colors (Raw: Stone Tone, Off White, Gray; Velvet: Slate, Ivory, Cotton), it can also be customized according to the RAL color chart, for perfect integration into architectural projects.

In short, OPTI’THERMIC® is :

Certified thermal performance for summer/winter comfort
Quick, easy installation
A lighter product, for the well-being of craftsmen
A single format for simplified logistics
A clean, customizable look
Compliance with environmental requirements and standards

OPTI’THERMIC® : 1 pallet = 1 house
Thanks to its 2-in-1 concept (sill + threshold), OPTI’THERMIC® simplifies logistics and reduces storage and transport costs. Fewer elements to manage, greater fluidity on the worksite.

Would you like to find out more?

Contact us for more information.

WESER, partner to builders committed to sustainable construction.

What is an OPTI’THERMIC® thermal support?: This innovative solution developed by WESER combines sill and threshold in a single product. Lightweight, insulating and quick to install, it reduces thermal bridges and improves the energy performance of buildings.
What are the advantages of OPTI’THERMIC® compared to a traditional seat support?: OPTI’THERMIC® reduces thermal bridges, saves 60% of installation time, eases handling and guarantees excellent resistance to humidity and mechanical stress.
For which types of building is OPTI’THERMIC® suitable?: It is suitable for all types of construction, particularly those involving interior insulation. It is compatible with most types of joinery, and can be used for both windows and door sills.
What sizes are available?: OPTI’THERMIC® is available for openings from 40 to 310 cm, and in one-piece versions up to 160 cm. The door threshold version (OPTI’THERMIC® 40) is available in 5 standard sizes, from 80 to 140 cm.
What finishes and shades are available?: Two finishes are available: Pierre Brute (cut stone look) and Velours (soft touch). In terms of color, 6 standard shades are available, with the option of customization via the RAL color chart.
Does OPTI’THERMIC® contribute to sustainable construction?: Yes, its insulation is made from 100% recycled and recyclable materials. What’s more, its lightweight design reduces the carbon impact of transport and storage, while offering excellent durability.