Oversills

Our oversill range provides a reliable window sill extension solution for external wall insulation systems and rendered façades. Designed to fit over an existing window sill, these profiles help protect the wall and insulation from water ingress while delivering a clean, modern finish.

Oversills designed for clean, weather-resistant window sill extensions

Aluminium oversill profiles are engineered for long-term protection against harsh weather conditions. They shed water away from the façade, reducing staining and weathering on render and insulation boards. Lightweight yet strong, they are suitable for both new builds and retrofit installation.

What an oversill is and how it protects the window sill

An oversill is a cover that fits over the existing window sill to extend its projection and improve drainage. By increasing the drip edge, it helps prevent water tracking back to the façade, protecting the window, surrounding materials and the substrate beneath.

They are commonly used on external wall insulation projects where added thickness requires a longer sill to maintain correct detailing.

Aluminium oversills with powder coated and white coated finishes

Our aluminium oversill options are available in powder coated and white coated finishes, including aluminium white for a clean, contemporary look that suits most façades.

Durable coatings for long-term weather protection

Each profile is finished with a robust coating system to withstand most conditions, including temperature fluctuations and exposure to moisture. This ensures consistent performance and reduces maintenance over time.

Smooth, modern appearance suitable for any façade

The smooth finish enhances the overall appearance of the house, complementing both modern and traditional designs. Profiles are supplied with a low tack film (peel off low tack) to protect the surface during transportation and installation.

Window sill extension solutions for EWI and rendered façades

Oversills are specifically designed to work with external wall insulation systems, accommodating added thickness from insulation boards and render layers. They are ideal for use around window and door openings, helping create a neat, functional detail.

Available in a variety of length, width and mm dimension options, including larger sizes, they can be selected to suit different project requirements.

End caps and end caps pair for neat, sealed oversill edges

Matching end caps and end caps pair options are available to seal the edges of each oversill. These provide a clean finish while preventing water ingress at the ends of the profile.

Combined with correct fixing methods and sealing, they ensure a professional, watertight installation.

Why oversills from EWI Store offer better fit, durability and installation efficiency

Our oversill range is selected for compatibility with EWI systems and ease of installation, helping installers achieve consistent results on site. Each product is manufactured to a high standard, ensuring durability, performance and a precise fit.

All items are held in stock for fast UK delivery, including shipping to areas such as northern ireland and the isle. Simply choose your required size, check price (shown excluding vat with vat add at checkout), and add to your basket.

If you need samples, technical information or help selecting the right model, you can contact our team via phone or email. We offer reliable service and expert advice to support your project from start to finish.