Window sill seals

Window sills play an important role in the protection and appearance of a building. They direct water away from the structure, protect against driving rain and contribute to the finish of the façade. The seal between the window sill and the window frame is a crucial component: it prevents moisture from penetrating the connection area, protects against heat loss and reliably keeps out dirt. A correctly selected and installed window sill seal not only extends the service life of the window sill, but also prevents consequential damage such as moisture ingress and mould growth.

What to look out for

Window sill seals are exposed to heavy loads – especially from UV radiation, temperature fluctuations, wind pressure and standing water. To ensure long-term functionality, it is crucial to choose the right seal geometry, use only weather-resistant materials, thoroughly clean the substrate before installation and apply the seal without tension. After installation, always check that the water drainage is working properly.

Indoor and outdoor use – the difference

Window sill seals can be designed for indoor or outdoor use, depending on requirements. In outdoor areas, they must be resistant to driving rain, wind pressure, UV radiation and large temperature fluctuations so that moisture cannot penetrate the building structure and water can drain freely. For indoor use, on the other hand, the focus is on airtightness, thermal insulation and a clean, visually appealing finish. While robust, weather-resistant materials such as TPE or silicone are essential for outdoor use, the main concern for indoor use is to create a tight, uniform connection that blends harmoniously into the overall picture. In the case of renovations, it should also be checked whether the existing construction requires special connection dimensions.

Precision for lasting functionality

GfA Dichtungen manufactures window sill seals that are specially designed to fit the geometries of common window sill systems. Millimetre-precise manufacturing, high-quality TPE material and sophisticated profile technology ensure a permanently secure seal – both in new buildings and in renovations.
Our production is carried out in accordance with DIN 16941 / 3302 and certified according to ISO 9001 and 14001 – for precision, quality and sustainability.

Material selection for window sill seals

For window sill seals, we consistently use TPE with a Shore hardness of 60 ShA. This material offers high elasticity for secure adaptation to the substrate, excellent resilience for consistent sealing, very good weather and UV resistance, and temperature resistance for use in both summer and winter. It ensures a long service life even under high mechanical stress.

Our window sill seals at a glance

Standard colours: window grey, black, white.
Available in almost all RAL colours for production quantities of 200 m or more.

Special design features:

• Model ADTP-1570-D – Double-strand design in the form of a ring seal. This design ensures improved sealing under high driving rain or wind loads and enables even pressure distribution around the entire circumference.

Our product range

As the area of application is clearly defined, our product range includes tailor-made solutions for different window sill systems. Each profile is designed to fit perfectly between the window sill and window frame, preventing both moisture ingress and cold bridges.

Standard window sill seals – reliable protection against water, wind and dirt, tailored to common systems in new buildings and renovations.

Ring seals such as model ADTP-1570-D – double-strand construction for window sills or objects in exposed locations that are subject to particularly high stress. The closed ring ensures uniform sealing along the entire length and increases resistance to water ingress even under extreme weather conditions.

Interior and exterior designs – specially developed profiles that are optimally adapted to the requirements of the respective area of application.

Installation & maintenance

Installation must be carried out on clean, dry contact surfaces. Remove old seals completely, insert new seals without stretching them and ensure that they fit evenly. Regular visual inspections and cleaning with mild detergents will extend their service life. Worn seals should be replaced immediately to avoid consequential damage.

GfA – expertise in sealing technology

With over 5,312 standard profiles, our own toolmaking facility, 17 extrusion lines, rapid prototyping and high-quality materials, we offer window sill seals of Made in Germany quality.

Advantages at a glance:

• Precisely fitting profiles for all common window sill systems
• High-quality TPE with 60 ShA for long-lasting function
• Interior and exterior designs for optimal adaptation to the intended use
• ADTP-1570-D ring seal with double strand design for maximum security
• Wide range of colours, including special colours from 200 m
• Personal advice and technical support
• Short delivery times from stock or custom-made