What is an MDF Window Board?
An MDF window board is a flat shelf fitted to the interior sill of a window opening. Also known as a window sill or window cill, it provides a clean, finished surface that protects the wall below the window and creates a practical ledge for plants, ornaments or simply a tidy finish.
At Univers Skirting & Architrave, our MDF window boards are supplied at a 25mm thickness, giving a solid, substantial feel that is far superior to thinner alternatives. All boards are factory-primed and ready to paint.
Why 25mm Thickness?
Our window boards are supplied at 25mm thick — thicker than many standard options on the market. This provides:
- Greater rigidity — no flex or bounce underfoot or when leant on
- Better durability — resists knocks, dents and everyday wear
- Superior finish — takes paint more evenly and looks more substantial
- Easier installation — easier to scribe and cut without risk of splitting
How Does an MDF Window Board Look?
Our window boards feature a clean, flat top surface with a smooth factory-primed finish. The front edge has a subtle pencil round detail for a neat, finished appearance. Once painted in your chosen colour — whether classic white, bold navy or contemporary sage green — the window board creates a crisp, professional finish that ties the room together.
Available Sizes
We offer MDF window boards in a range of widths to suit different window reveal depths. All boards are supplied at 25mm thickness and can be cut to length on site.
Moisture-Resistant Option
Window sills are exposed to condensation and temperature changes, making moisture resistance an important consideration. We offer our window boards in both standard MDF and moisture-resistant MDF — the moisture-resistant option is recommended for:
- Kitchens
- Bathrooms
- Any window prone to condensation
How to Install an MDF Window Board
- Measure the width and depth of your window reveal
- Cut the window board to the correct width, allowing for any scribing to the wall
- Scribe the back edge to fit snugly against the wall if needed
- Apply a bead of grab adhesive to the window sill surface
- Press the board firmly into position and check it is level
- Secure with screws from below if required
- Fill any gaps with decorators caulk and prime any cut edges
- Paint to your chosen colour
For a full step-by-step guide, see our How to Install MDF Window Boards article.
Why Choose Univers for Your Window Boards?
Our 25mm MDF window boards are manufactured in the UK to exacting standards. Factory-primed and ready to paint, they save time on site and deliver a consistently smooth finish. We offer fast delivery across Hampshire, Surrey and the wider UK, with local delivery available in the Gosport area.
Browse our full range of window boards or contact our team for advice on your project.