A windowboard, also known as an internal window sill, is the flat, horizontal surface at the bottom of a window on the inside of your home. It provides a nice finished look and can be used to place decorations like plants or pictures.

A window sill is the horizontal piece that runs along the length of the window, at the bottom of a window frame, on the outside of the building. It helps keep rainwater from entering your home.

A windowboard serves several important functions in a home:

1. Aesthetic Enhancement: Provides a finished, polished look and integrates the window into the room’s design.

2. Practical Surface: Creates a usable space for plants, photos, or décor.

3. Protection: Protects walls from condensation and wear.

4. Insulation: Helps reduce drafts and improves energy efficiency.

5. Structural Support: Helps maintain stability around the window opening.

As our window structures are bespoke products, once you have selected your ideal finish (bullnosed edge or square edge) we will ask you for the dimensions of your window in terms of ideal length and width. We recommend to all customers that the dimensions they provide us with include adequate length for the horns of the window structure - that is, an extension of the sill along the front which strengthens the joint between the sill and the edge of the window. The horn is both aesthetic and structural, adding strength to the sill and ensuring it blends neatly into the surrounding wall.
This information should be provided in millimetres as per the order pages, so that the window board can be made to the right size for your property.

Yes, all of our window boards are machined in-house to customer specification, allowing us to produce custom sizes to suit your project. Our online formula allows you to adjust width, length (up to 3m) and edges. If you’d like further customisation or longer lengths than 3m, please feel free to contact us via [email protected], and we’ll be happy to help out.

How much your window board overhangs is your own design choice. We’d usually recommend between 20mm to 50mm overhang at the front and 50mm side overhang (horns) on each side – adding 100mm to the full width of the board.

The amount a window board overhangs is largely a design preference and may vary depending on the style of the property and installation requirements.

As a general example, some installations use approximately 20mm–50mm front overhang, with side overhangs (horns) of around 50mm on each side. This would increase the overall length of the window board by approximately 100mm.

Side horns are typically left longer and trimmed on site by the installer to suit the wall conditions and achieve the desired appearance. This also allows for a more accurate fit, particularly where walls may not be perfectly square.

We recommend confirming requirements with your installer prior to ordering, as preferences and site conditions can vary.

Our standard thickness is 26mm, as this best suits our rounding cutter. However, we can provide thicknesses from 18mm upwards.

Please note:

Below 25mm, the bullnosed/returned end window board will not be fully rounded and will have a more pronounced curved profile.

Above 27mm, the edges are typically rounded on the top and bottom with a flatter front face.

Our hardwood window boards are supplied freshly machined but unfinished as standard, while our MDF window boards are supplied pre-primed. This means they are ready for painting, staining, or varnishing on site.

Yes, however we recommend moisture-resistant MDF or hardwoods where appropriate. Proper sealing and finishing is advised after installation.

When the ends are returned, it means they are rounded. On a bullnosed edge window board, the front edge profile is continued around the ends for a clean, finished appearance. Returned ends also help conceal any exposed end grain and provide a more professional finish once installed.

No, we do not cut out the horns prior to supply. Boards are supplied square so installers can cut them on site for a precise fit.

We take care to package window boards securely with bubble wrap, shrink wrap, and end protection to minimise damage in transit.